Glossary of Botanical Terms

This glossary of botanical terms is a list of terms related to botany and horticulture. These include flower terms, plant terms and words, botanical definitions and terminology.

What is botany? Botany is a branch of scientific study in which plants themselves are examined. If you are looking for general answers related to botanical and horticulture topics, education, job and carrier opportunities, check out our Botanical Frequently Asked Questions page.

-merous: A suffix preceded by an Arabic number or numeric prefix such as tri-, indicating how many of each part a flower possesses; 5-merous would be a flower with 5 sepals, 5 petals, etc., while trimerous would have three of each part.
A horizon: The uppermost layers of soils consisting of partly decomposed plant remains and relatively fresh leaves and other plant debris; the surface mineral layer, high in organic matter and dark in color; and the lighter colored layer where leaching of solutes and suspended materials occurs.
AARS: An acronym representing the name All-America Rose selections, Inc., an association of commercial rose growers that tests and approves new rose varieties for commercial use.
abaxial: Facing away from the axis.
abbreviated (syn. abridged): Shortened, as when one part is shorter than another.
aberrant: Atypical or unusual; not normally occurring.
abiogenesis: Spontaneous generation of life from nonliving material.
abiotic: Nonliving, as opposed to biological.
abiotic stress: Nonliving environmental factors such as frost, drought, excessive heat, high winds, etc., that can have harmful effects on plants.
abiotic transformation: Any process in which a chemical in the environment is altered by nonbiological mechanisms, e.g., by exposure to sunlight.
abortion: Imperfect development or nondevelopment of an organ.
abortive: Defective or barren. Describes especially but not exclusively reproductive structures.
above: 1. Refers to the adaxial (upper/outer) surface of a leaf, petal, sepal or scale. 2. Refers to the part of a stem, bulb, tuber, branch, or inflorescence that is the greatest distance from the attachment, following the stem/branch; if a branch arches with a flower at the tip drooping nearly to the ground, the flower is said to be above the highest point of the branch.
abrade: To scrape off.
abrupt: Suddenly narrowed or cut off.
abscisic acid (abr. ABA, syn. abscisin): A plant hormone that promotes leaf.
absciss-layer: A belt of tissue preparing for separation, especially at the connection of a leaf to the stem.abscission, fruit drop, and seed dormancy, and has an inhibitory effect on cell elongation.
abscission (adj. abscissile): The normal shedding of leaves, flowers or fruit from a plant at a special separation layer, or abscission zone.
abscission zone: The area of separation when a plant sheds a leaf, flower or fruit.
absent petiole: A leaf without a petiole; sessile.
absorb (n. absorption): To suck up or take up, e.g., plant roots absorb water.
absorbents: Antacid herb.
absorption spectrum: A graph of the amount of light a substance absorbs, plotted as a function of energy, frequency, or wavelength.
acariasis: An infestation with or a disease caused by mites.
acarodomatia: Domatia which have adapted to provide shelter to beneficial mites.
acaulescent: A plant that is stemless or apparently so, or with the stem subterranean.
accelerators: Admixtures that decrease the setting time of concrete by increasing the rate of hydration.
accessory: Auxiliary, subsidiary; as the parts of a flower beyond the necessary male and female organs, such as petals and sepals.
accessory bud: Buds which are at or near the nodes but not in the axils of the leaves.
accessory fruit: A fruit, or group of fruits derived from a singleflower, in which the conspicuous, fleshy portion develops from the receptacle and is shed with the true fruit(s) attached.
accessory organs: Parts of a flower that are not directly connected with male and female organs, e.g., petals and sepals, etc.
acclimate (n. acclimation): To adapt to a new environment, or a change in the environment.
acclimatization (syn. adaptation): The physiological process by which an organism adapts to a new environment.
accrescent: Gaining in girth or length with age or following fertilization, or growing together, as the calyx of some plants after flowering, such as the ground cherry.
accumbent: A cotyledon having the edges lying against the radicle.
aceriform: Shaped like a maple leaf; deeply lobed.
acerose: Sharp, solid, needle-like.
achene: A small dry and hard 1-celled, 1-seeded indehiscent fruit.
achenecetum: A cluster of small seeds (achenes), as in buttercups, Ranunculus.
achenocarp: Any dry fruit that does not open by itself.
achlamydeous: Without a perianth, e.g., the flowers of a willow.
achlorophyllous: Lacking chlorophyll; appearing without green color.
acicular: Needle-shaped. If solid, may be either round or grooved in cross section.
aciculate: 1. Describes a surface that is etched with fine lines, as if scratched by a needle. 2. Marked with what appears to be pin pricks, usually arranged at random.
acid rain: Rain which has turned acidic due to the presence of sulfur or nitrogen oxides in the atmosphere. Acid rain can harm and even kill plants and aquatic life.
acid soil (adj. acidic): Soil with a pH level below 7 is considered acidic; also called sour.
acidifier: An additive that decreases the pH (and increases the acidity) of soil.
acidophile (adj. acidophilic): A microorganism that can, or must, live in an acidic environment. See also: alkaliphile.
acidulous: Slightly acidic.
acinaceous: Covered or filled with kernels.
acinaciform: Shaped like a half moon.
acinose: Resembling a bunch of grapes.
acondylose: Stems which lack joints or nodes.
acorn: The hard-shelled, one-seeded fruit of the oaks (Quercus) which consists of a nut which is partly enclosed by the cupule, or cap.
acotyledonous: Having no seed leaves, or cotyledons.
acre: Land measurement of 43,560 square feet, roughly the size of a football field.
acrid: Harsh and bitter in taste.
acrocarpous: In mosses, having the sporophyte terminal on a stem or ordinary branch.
acrocidal capsule: A dry fruit which dehisces by slits at the terminal.
acrodome: With the main veins ending at the leaf tip.
acrodromous: Describes leaves with two or more primary or strongly developed secondary veins running in convergent arches towards the apex. Arches not recurved at base. See also: brochidodromous, eucamptodromous, semicraspedodromous.
acropetal: Developing in a succession from the base and towards the apex. See also: basipetal.
acroscopic: Facing upwards, towards the apex of the axis on which it is borne. See also: basocopic.
acrostichoid: Having sporangia apparently scattered on the surface of the fertile lamina.
acrotonic: Describes flowering seasonal shoots which produce leaves below the inflorescence. See also: basitonic.
actinomorphic: Refers to flowers that can be divided into symmetrical halves along any diameter. See also: zygomorphic.
actinostelic: Refers to a vascular strand where ribs radiate outward.
active transport: The movement of a chemical substance by the expenditure of energy through a gradient (as across a cell membrane) in concentration or electrical potential and opposite to the direction of normal diffusion.
actual: As in actual nitrogen; calculating the amount of the mineral present, e.g., calculating a 25-pound bag of fertilizer containing 22 percent of nitrogen as the equation 25 pounds X .22 = 5.5 pounds of actual nitrogen.
aculeate: Prickly; beset with prickles.
aculeiform: Shaped like a prickle.
aculeolate: Beset with diminutive prickles.
acumen: The gradually tapering narrow point of an acuminate leaf.
acuminate (n. acumination): The shape of a tip or base of a leaf or perianth segment where the part tapers gradually and often in a concave manner.
acutangular: Refers to a stem that is sharply angled.
acute: Terminating with a sharp or well defined angle.
acyclic: Arranged in spirals as opposed to whorls.
adaptability: Proficiency of an organism to make changes improving survivability and reproduction in its habitat.
adaptation (alt. adaption): 1. The ways an organism becomes better fitted to survive and reproduce in a particular environment. 2. A genetically changing characteristic that raises an organism's ability to survive.
adaptedness: The genetic characteristics by which an organism is suited to its environment.
adaptive capacity: The genetically set range or flexibility of reactions of an organism enabling it to respond in different ways to differing conditions.
adaptive radiation: The evolution of new species or subspecies to fill unoccupied ecological niches.
adaptive selection: The evolution of comparable forms in separate but ecologically similar areas.
adaxial: Facing toward the axis, as the upper surface of a leaf.
additive: Material added to a substance, such as fertilizer, to better enable it to perform the desired function.
adenosine diphosphate (abr. ADP): An ester of adenosine that is reversibly converted to ATP for the storing of energy by the addition of a high-energy phosphate group.
adenosine triphosphate (abr. ATP): A phosphorylated nucleoside that supplies energy for many biochemical cellular processes by undergoing enzymatic hydrolysis especially to ADP. An energy-rich phosphorous compound that is important in the transfer of energy in organisms.
adherent: Joined, but not united.
adiabatic: Refers to an event in which heat is neither gained nor lost.
adjacent: Next to each other, but without touching or overlapping.
adjustment: Functional, never structural, changes by which an organism becomes better suited to its environment. See also: adaptation.
admixture: A material other than water, aggregates, or cement that is used as an ingredient of concrete or mortar to control setting and early hardening, workability, or to provide additional cementing properties.
adnate: United; fused, as the inferior ovary with the calyx-tube. Adnate anther: one attached for its wholelength to the inner or outer face of the filament.
adobe: A fine calcareous clay or silt, often used for construction purposes.
adpressed: Pressed flat against another organ.
adsorption: The attachment of molecules or ions to outer surfaces or interfaces.
advance growth (syn. young growth): Seedlings and saplings appearing under the canopy ready to fill in forest openings made available by the death of a mature tree from logging, lightning kills, etc.
adventitious: Describes an organ growing where it is not normally expected, e.g., roots growing from a stem.
adventitious root (syn. stem root): A root that arises from a stem, rather than from the primary root.
adventitious species: An alien or exotic species; an invasive species.
adventive: Describes an exotic species recently introduced to an area or imperfectly naturalized.
adventive taxa: Organisms that were not native to an area, and have now naturalized.
adze (alt. adz): A tool for shaping wood having a curved blade arched downwards and at a right angle to the handle.
aelophilous: Refers to plants which spread seeds or pollen by wind.
aeolian (alt. eolian): Refers to the wind, or to soil which has been moved by wind.
aerate: To supply or impregnate with air.
aerating root: A root structure that rises above ground, usually above water, to allow the plant to absorb air.
aeration: The processes by which air and other gases in a medium are exchanged or refreshed.
aerenchyma: Tissue with thin walled cells separated by large, gas-filled spaces that facilitates gaseous exchange and maintains buoyancy; typical of aquatic plants.
aerial: Refers to any plant part that is above water in aquatic plants; less often used with terrestrial plant parts found above ground.
aerial photograph: A map-like picture taken of the ground from high in the air, showing roads, fields, and other man-made objects as well as natural features such as rivers.
aerial roots: 1. Roots borne wholly above ground, as the attachments of vine forms of Toxicodendron radicans which penetrate tree bark. 2. Rooting shoots of epiphytes.
aerobic (n. aerobe): Living, active, or occurring only in the presence of oxygen.
aerobiosis: All life that grows in the presence of free oxygen.
aeroplankton: Microorganisms which float in the air, as plankton floats in water.
aerotaxis: An involuntary response of a living thing to a gas, such as a plant curving toward a more concentrated source of carbon dioxide.
aerotropism: An organism's growth determined by the presence of oxygen.
aestidurilignosa: Woodland with mixed evergreen and deciduous hardwoods.
aestival (alt. estival): Appearing during the summer season. See also: aspection.
aestivation: 1. Estivation. 2. The arrangement of the perianth or their lobes in an unexpanded flower bud. See also: vernation.
affinity: That relationship between organisms which shows they share a common origin; used occasionally to show the similarity among communities.
affixed: Fastened upon.
afforestation: The process of starting a new forest in an area where none existed; to do the same to replace a previous growth is reforestation.
afoliate: Without leaves.
after-ripening: 1. Metabolic changes that must take place in a seed to overcome dormancy. 2. The dormancy period following seed formation, necessary for embryo changes that insure germination.
aftermath: 1. A second growth crop, also called a rowen. 2. The outcome, especially of a disaster, as in the aftermath of a forest fire.
agamic: Asexual.
agamogenesis: Asexual reproduction, as by budding, cell division, or parthenogenesis.
agamospecies (alt. agameon, syn. binom): A group of individuals in which reproduction is almost exclusively by asexual means.
agamospermy: Apogamy where sexual union is not completed, yet the embryo is produced from the inside layer of the female gametophyte.
agamosporous: Having a life cycle in which chromosome segregation and recombination does not take place.
agamous: Without stamens or pistils; neuter, sterile.
agar: A gelatinous substance produced by red algae, often used as a culture medium.
agaric: 1. The dried fruiting body of a fungus formerly used in medicine. 2. Any of a family (Agaricaceae) of fungi with the sporophore usually resembling an umbrella and with numerous gills on the underside of the cap.
age and area: The hypothesis that the larger the area covered by a species, the older that species is.
age class (syn. even aged): Refers to a stand in which all the trees or other perennials started growth in the same regeneration period. See also: monoculture.
age distribution: The classification of groups within a community according to age or certain periods such as prereproductive, reproductive, postreproductive.
ageotropic (alt. apogeotropic): Said of parts that would be expected to grow as gravity pulls, but instead grow upward, such as the knee roots of cypress, Taxodium spp./I>.
agglomerate: Together in a head, as the florets of red clover, Trifolium pratense; clustered.
agglutinate: Stuck together, as in pollen masses of orchids.
aggradation: The gradual filling of depressions in the earth's surface by soil deposition, such as the deposition at a lake's bottom; or the opposite, the wearing away of mountain tops, reaching toward a level surface.
aggregate: 1. Clustered. In mosses, applied to two or more sporophytes from one perichaetium. 2. Composed of mineral crystals of one or more kinds or of rock fragments. 3. A material such as sand or gravel mixed with a binder, such as cement, to produce mortars and concrete. 4. A group of closely-related species.
aggregate flowers: Crowded into dense clusters or tufts, as in Scabiosa atropurpurea.
aggregate fruit: Describes a fruit, such as a raspberry, which consists of a fused cluster of several fruits, each one formed from an individual ovary. See also: syncarp.
aggregate species: A group of species that are so closely related that they are regarded as a single species.
aggregation: The coming together of organisms into a group, such as seedlings growing near the base of a parent tree. See also: community.
aging: When said of a lake, refers to the enrichment of waters, rapid growth of aquatic plants, and sedimentation which accelerate the death of a lake.
agonistic behavior (alt. agonistic behaviour): Aggressive or defensive actions, such as fleeing or fighting, brought on by the interaction between individuals usually of the same species.
agrarian zone: That portion of a jurisdiction that can be or is farmed.
agrestal: Growing wild; especially weed plants growing on farms.
agrestic: Rural; rustic.
agrobiology: The study of plant nutrition and crop production in relation to soil control.
agroforestry: Land management for the simultaneous production of crops and trees.
agrology (syn. edaphology): The study of soils.
agronomy (adj. agronomic): The theory and practice of soil management and field crop production.
agrophilous: Refers to organisms which grow best in cultivated fields or other manmade areas.
agrostology: The branch of systematic botany which encompasses grasses; graminae.
aianthous: Flowers all year; semperflorus.
aiphyllus: Evergreen.
air layering (alt. air-layering, syn. Chinese layering, syn. gootee, syn. marcotting): A method of propagation where a cut is made in a woody stem and surrounded by damp peat moss held in place by a wrap. When roots form, the stem can be removed and planted.
air mining: Processing air to recover minerals in suspension or solution.
akene: A dry, one-seeded indehiscent fruit, with the pericarp fitting closely around the seed.
ala (pl. alae): Wing; in ferns, the narrow membrane laterally bordering a stipe, rachis, or costa.
alar: Describes the cells at the basal angles of the leaf, commonly different from the cells of the main part of the leaf, being shorter and often nearly square, or inflated and hyaline, and often highly colored.
alate (syn. aliferous): Winged.
albedo: The proportion of incident radiation, usually light, that is reflected by a body such as a cloud.
albescense (adj. albescent): The act of turning white; whitish.
albidus: Whitish.
albino: A flower that lacks normal color; white.
albumen: Starchy and other nutritive material in a seed, stored as endosperm inside the embryo sac, or as perisperm in the surrounding nucellar cells; any deposit of nutritive material accompanying the embryo.
albuminous: Having albumen.
albuminous cell: A gymnosperm phloem parenchyma cell closely associated with an adjacent sieve cell.
aletophyte: A plant growing in a mesic habitat.
alga (pl. algae): A general name for the single-celled plant plankton, seaweeds, and their freshwater allies.
algae bloom: Rapid growth and death of aquatic plants, especially during hot weather in highly nutritious water.
algal layer: A thin layer of green or blue-green algae lying just beneath the cortex of a lichen.
algin: A gelatinous substance produced by brown algae, used in food and pharmaceutical preparations.
algoid: Resembling algae.
algology: The study of algae.
alien: An exotic; an introduced plant which has naturalized.
aliferous: Winged.
aliquote: The constant of temperature required for the development of a certain stage in the life cycle of an organism. See also: temperature summation.
alkali: A soluble salt obtained from the ashes of plants and consisting largely of potassium or sodium carbonate, e.g., a hydroxide or carbonate of an alkali metal, having marked basic properties. 2. Alkali metal. 3. A soluble salt or a mixture of soluble salts present in some soils of arid regions in a quantity that is detrimental to agriculture.
alkali reserve: The total amount of dissolved substances predisposed to maintain the normal alkalinity of a body of water or an organism's internal body fluids.
alkali sink: A land basin in which water evaporation produces high salt concentrations that may, or may not, support salt marsh vegetation.
alkaline (adj. alkalinity): 1. Of, relating to, containing, or having the properties of an alkali or alkali metal. 2 A base; having a pH of more than 7.
alkaline soil (alt. alkali soil, syn. basic soil): Soil with a pH level above 7; also called sweet.
alkaliphile (alt. alkalophile, syn. basophile, adj. alkaliphilic): An organism that prefers, or can tolerate, alkaline conditions, typically in the range of pH 8-11. See also: acidophile.
allagostemonous: A flower having stamens attached to both the petal and receptacle.
allantoid: Sausage-shaped.
allee: A walkway lined with trees or tall shrubs.
allele (alt. allelomorph, syn. dominant character): Any of the alternative forms of a gene that may occur at a given locus, one provided by each parent and determining charateristics such as eye color.
allelopathy (adj. allelopathic): The inhibition of growth of one plant species by another due to the release of chemical substances.
allergen (adj. allergenic): A substance which induces allergic symptoms like rash, inflammation, etc.
allergy: Sensitivity resulting in reactions such as rash, inflammation, etc., when exposed to an allergen, e.g., pollen, strawberries, etc.
alley: A garden or park walk bordered by trees, shrubs, or flower beds.
alliaceous: Having the smell or taste of garlic.
alliance: A group of plant associations classed together on the basis of similarities in floristic and sociological characters.
allochoric: Refers to a species occurring in two or more similar communities in the same region.
allochthonous: Originating from outside a system, such as the leaves of terrestrial plants that fall into a stream. See also: autochthonous.
allogamy: Reproducing by cross-fertilization.
allogenic succession: The replacement of one kind of community with another because of a change in the environment which was not produced by the plants themselves, e.g., a decrease in soil moisture.
allohexaploid: Having sex genomes with one or more sets derived from a species different from the other sets.
allopatric: Refers to two or more species having nonoverlapping ranges of distribution. See also: sympatric.
allopelagic: Refers to any organism occurring at any depth of the ocean.
allopolyploid: A polyploid individual or strain having a chromosome set composed of two or more chromosome sets derived more or less complete from different species.
allotetraploid: Having four genomes with two sets (rarely one) coming from a different species than the others.
allotrophic: Refers to lakes or ponds which receive organic materials from the surrounding land by washing.
alluvial: Describes something related to, or caused by, a river or stream, such as alluvial deposits.
alluvial fan: A delta at the mouth of a stream or river formed by the depositing of transported materials when the flow lessens.
alluvial soil: Soil deposits at the mouth of a stream or river, characterized by little or no modification of the original transported material by soil-forming processes.
alluvion: Detritus and sediments deposited by streams or the action of waves and currents in larger bodies of water; this contributes to the gradual addition of land and loss of lake or wetland.
alluvium: Sediments which were transported by a stream or river, then deposited when the stream flow lessened. See also: alluvion.
alm: A high mountain meadow, either alpine or subalpine.
almanac: Calendar to which astronomical data and various statistics are added.
alpage: An upland pasture consisting of natural plants which are used for grazing animals at the height of summer.
alpine: 1. A plant native to a mountainous region. 2. Refers to the area of a mountain above the tree line, or to organisms which grow there.
alteratives: Herbal medicines which can work a gradual change in the system.
alternate: Describes leaves that are not opposite to each other on the axis, but arranged singly at different heights.
alternation of generations: The complete life cycle of plants with very different sexual and asexual phases, such as the successionof haploid gametophytes and diploid sporophytes found in ferns, Pteridophyta.
alternes: Two or more types of communities alternating with each other in a more or less restricted area.
alternitepalous: Describes floral parts, inserted alternately with the tepals.
altherbosa: Communities with tall herbaceous plants, especially in denuded forest areas.
altimeter: An instrument for determining altitude.
alulate: Having a very narrow wing.
alvar: A Swedish term for a habitat type consisting of dwarf shrubs.
alveolate: Honeycombed; having angular depressions separated by thin partitions.
alveolation: A honeycombed condition.
amanthophilous (syn. ammocolous, alt. ammophilous): Refers to organisms which live in sand.
amendment: Alteration or change, especially for the better, as when adding a soil amendment.
amensalism: The state or interaction in which one organism is reduced while another is not influenced. See also: commensalism.
ament: A catkin, or scaly spike.
amentaceous: Refers to plants which produce catkins.
amentula: Applied to the special antheridia-bearing branches of Sphagnum.
American Rose Society (abr. ARS): An educational, nonprofit organization dedicated exclusively to the cultivation and enjoyment of roses.
amethystine: Violet-colored.
ametoecious: Refers to a parasite which is restricted to a single host, i.e., species specific.
amino acid: One of the organic, nitrogen-containing units of which proteins are composed.
amitosis: Direct division of the nucleus of a cell without mitosis.
ammate: A compound of ammonium sulfate, often used as an herbicide.
ammonification: The formation of ammonia compounds from organic materials containing nitrogen.
amnion (alt. amniotic fluid, alt. amniotic waters): The liquid surrounding an embryo while in uterus or in an egg.
amniote: Animals whose embryos develop within a fluid-filled sac, e.g., some reptiles, birds and mammals.
amorphous: Shapeless, a form not regular or predictable.
amphibious: Capable of living on land or in the water.
amphicarpic: Producing two different types of fruits; sometimes said of plants which bear more than one crop each year.
amphicarpogenous: Producing fruit above ground which then becomes buried, e.g., peanuts, Arachis hypogaea.
amphichromatism: Having flowers of different colors appearing in different seasons.
amphicryptophyte: A marsh plant with some underwater vegetative parts.
amphidiploid (alt. amphiploid): A tetraploid having two sets of genomes coming from different parent stock.
amphigeal: Producing two types of flowers, one coming up directly from the root, the other on upper stems.
amphigean: Native of both Old and New Worlds.
amphigenesis: The joining of gametes to form a zygote.
amphigenetic: Refers to an organism or a part of the growth cycle that produces zygotes.
amphimixis: Sexual reproduction; the joining of parental characters.
amphiphyte: A plant growing in the edge of wetland and water showing amphibious characteristics.
amphiploid (alt. amphidiploid): A variation on polyploid in which there are two sets of chromosomes, each set coming from a different species.
amphirhinal: Refers to an organism with two noses.
amphitheater (alt. theatre, syn. theater): A hillside or depression with tiers or terraces cut into it, resembling a classical outdoor theater and usually used for that purpose.
amphithecium: The outer layers of cells of the sporangium.
amphitropous: Half inverted and straight, with the hilum lateral; an ovule that is curved back along its funiculus so that the base and micropyle are close together. Describes an ovule or a seed.
amphoteric: Refers to the ability of a substance to react either as an acid or a base.
amplectant: An organism or organ with the ability to clasp or twine, like a tendril.
amplexicaul: Clasping the stem.
ampliation: The process of enlarging or amplifying.
ampule (alt. ampulla, adj. ampulliform, adj. ampullaceous): A hollow flasklike organ shaped like a bladder or squat round bottle; e.g., the traps and floats such as those found on the leaves of Nepenthaceae or Utricularia.
anabiont: A plant that produces flowers and fruits many times; a perennial.
anabiosis: Revival of an organism after apparent death, like the resurrection plant, Anastatica.
anabolism: The process of building up protoplasm from simple substances.
anadromous: Having the first lobe or segment of a pinna or frond arising toward the apex/tip.
anaerobe: An organism which can survive in the absence of oxygen.
anaerobic: Describes a process that occurs with little or no oxygen present.
anaerobic respiration: Gaseous exchange in which the hydrogen removed from the glucose during glycolysis is combined with an organic ion instead of oxygen.
anaerobiosis: The existence of life without oxygen.
anaerophytobionts: Soil flora which exist without oxygen.
analgesic: An herbal medicine which can relieve pain.
analogous: Of similar function, but of different evolutionary descent. See also: homologous.
anamniote: An animal lacking embryonic membranes or amnion.
anandrous: Refers to flowers that have no stamens.
anastomose (v. anastomosing, adj. anastomosed): Netted, as are veins in a leaf.
anastomosing: Connecting by cross-veins and forming a network.
anastomosis: The connection of various parts to form a network, as in leaf veins.
anatomy: The study of the structure of an organism and the relationship between its parts.
anatropous: An ovule that is inverted and straight, with the micropyle next to the hilum and the radicleconsequently inferior.
anauxotelic: Describes inflorescences, parts of inflorescences or axes that do not end in a flower, and in which growth does not continue beyond the flowering region. See also: auxotelic.
anchor root: A large root serving mainly to hold a plant in place in the soil.
anchor-ice: Frozen water that forms at the bottom of a stream.
ancipital (adj. ancipitous): With both edges sharp, as some flattened stems.
androconia: Modified scales on the wings of butterflies, e.g., Lepidoptera, that produce a sexually attractive odor. See also: pheromones.
androdioecious: A plant breeding type in which a species, to produce seeds, must have a male plant with flowers having only stamens and a bisexual plant with flowers having both stamens and pistils. See also: dioecious.
androecium: Refers collectively to the stamens of one particular flower.
androgynophore: A stalk bearing both the androecium and gynoecium of a flower above the perianth.
androgynous: 1. Of an inflorescence composed of both staminate and pistillate flowers. 2. With antheridia and archegonia in the same cluster of leaves, i.e., either synoicous or paroicous.
andromonoecious: Refers to species that have bisexual and male flowers on the same plant.
androphile: A plant that grows most successfully around humankind.
androphore: A stalk bearing the androecium.
androsporangium: The receptacle in which androspores are formed.
androspore: The minute reproductive body, which gives rise to the (often exceedingly obscure) male plantlet in the sexual generation.
anemochore (alt. anemochory): Dispersal of organisms, such as seeds, by wind. See also: diaspore, disseminule.
anemogram: The graphic record of wind velocity made by an anemograph.
anemograph: An automatic instrument for graphic recording of wind sp.ed.
anemometer: An instrument that measures wind sp.ed, but does not necessarily record it. See also: anemograph.
anemophious (alt. anemophilous): Refers to plants which are pollinated almost exclusively by wind. See also: anemochory, entomophilous.
anemoplankton: Microorganisms transported by wind.
anemotaxis: The reaction to wind experienced by a free-moving organism.
anemotropism: Movement or growth of cells or organisms in response to wind.
aneroid barometer: An instrument that precisely measures atmospheric pressure to allow calculation of altitude.
aneuploid: Refers to the presence of an irregular number of chromosomes, higher or lower than multiples of the haploid number. See also: euploid.
anfractuose (alt. anfractuous): 1. Tightly twisted together. 2. Closely sinuous.
angiosperm: A flowering plant with ovules contained inside the ovary.
angiospermous: Having the seeds borne within a pericarp.
angle of repose (syn. critical slope): The maximum degree of gradient on which soil or loose rock remain stable.
angled: Having evident ridges.
angular (alt. angulate): Angled. Refers to an organ that shows a specific number of angles, e.g., mints, Labiatae, which have stems that are 4-angled, and are square in the cross section.
angular cells: See also: alar.
angustifolia: Narrow leaves.
angustiseptal: Having a fruit with narrow partitions, as the silicle of Cruciferae.
angustiseptate: Having narrow partitions. See also: latiseptate.
anhydrous: Refers to a substance which contains no water, like anhydrous ammonia.
animal unit: A standardized measure to understand the needs of different kinds of livestock in relation to forageresources. A mature cow of about 1000 pounds (455 kg.) is the standard unit, and the feed needed is equal to one horse, one mule, five sheep, five swine, five goats, or eight geese.
animal unit month: A measure of forage needed to maintain one animal unit for 30 days.
anion: A negatively-charged ion, such as chlorine. See also: cation.
aniso-: A prefix meaning unequal or dissimilar.
anisophyllous: Refers to paired leaves which are different in size or shape, common in trailing stemmed gesneriads.
anisophylly: The presence of two kinds of leaves on one plant as in Selaginella and some cedars, Juniperus. See also: dimorphism.
annotinal: Appearing yearly.
annual: A plant whose life cycle is of only one year's duration.
annual production: The amount of yield each year by an organism or group.
annual ring: The layer of wood produced by a single year's growth of a woody plant.
annual seasons: The major climatic periods of each year: vernal, estival, autumnal, and hibernal.
annual succession: The routine occurrence of plants and animals in an area during each year, such as spring bulbs being replaced by annual flowering plants, and subsequently replaced by autumn perennial flowering plants.
annual turnover: The total accumulation of living organisms produced in one year for a certain area. See also: biomass.
annuation: The highs and lows from year to year in abundance or performance of organisms caused by differences in environmental conditions such as temperature and moisture.
annular: In the form of a ring.
annular corona: Raised fleshy tissue, usually in a ring, on the corolla around the base of the staminal column but not closely adnate to it.
annulated: Made up of rings.
annulus: 1. A ring of cells of the leptosporangium (the sporangium of higher ferns), which causes the sporangium to open and to discharge its spores.
anodynes: Herbal medicines that can counteract pain but are milder than analgesics.
anomalicidal capsule: A dry fruit which dehisces irregularly; a rupturing capsule.
anoxia: Condition resulting from an extreme lack of oxygen, usually resulting in permanent damage.
anoxic: Greatly deficient in oxygen.
antagonism: The depressive effect of one organism upon another, such as certain grasses like timothy hay on the production of alfalfa hay.
antecedent moisture: The degree of liquid which has soaked into the soil at the start of the runoff period.
antemarginal: Inside of, or not extending quite to the margin.
anterior: Away from the stem, midrib, pistil or other organ. On a lipped flower, the bottom lip is anterior, the top lip is posterior. Sometimes the anterior lip is less correctly called inferior or exterior.
antero-lateral: In front and on the sides.
anthelmintics: Herbal medicines that can destroy or expel intestinal worms.
anther: The polliniferous part of a stamen.
anther sac: A pocket-shaped unit containing pollen. In many plants, the anther has two lobes, each with two pollen sacs.
antheridium (pl. antheridia): In cryptogams, the organ corresponding to an anther that produces male gametes; the male organ on the prothallium.
antheriferous: Anther-bearing; containing anthers.
antheroid: Similar to an anther.
antherozoid: Sperm, male gamete; one of the minute organs developed in an antheridium.
anthesis: The time of expansion of a flower.
anthocarp: A pseudocarp consisting of the true fruit and the base of the perianth.
anthocyanin (adj. anthocyanous): A blue to purplish-red coloring agent, water soluble.
anthracnose: A fungus that forms grayish/whitish spots on leaves and stems.
anthropic (alt. anthropeic): Refers to the influences of humankind in contrast to natural influences, such as the introduction of IPM pest control.
anthropochore (alt. anthropochory): Dispersal of organisms, such as seeds, as a result of human activity. See also: anemochory.
anthropogenous: Refers to practices of humans, such as cultivation or monoculture.
anthropophilous: Refers to plants which grow near humans and their dwellings, such as dooryard violet, Viola odorata.
anti-: Against, opposed to.
anti-inflammatory: Refers to herbal or other medicines that can ease or neutralize swelling, heat, and pain.
antiallergenic: Refers to herbal medicines that can reduce or relieve allergic reactions.
antiaphrodisiac: Refers to herbal medicines that can reduce sexual desire.
antibiosis: The reaction, often death or sterilization, produced in organisms by an antibiotic.
antibiotic: Substance that slows the growth or multiplication of, or kills, a living organism; usually referring to bacteria.
anticline: A geological structure or arch formed by strata from opposite sides rising upward in a common line. See also: syncline.
anticyclone: An air mass with high atmospheric pressure surrounded by lower pressure areas, in which the circulation of the air is clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.
antifungal: Refers to herbal medicines that can slow the growth or multiplication of fungi, or kill them.
antihistamine: Herbal or other medicines that can neutralize the effect or inhibit production of body histamines.
antimicrobial: Refers to herbal or other medicines that can slow the growth or multiplication of microorganisms, or kill them.
antipetalous (alt. antepetalous): Opposite the petals.
antique rose: A rose which has been in cultivation since at least before 1900. Often refers specifically to an Old Garden Rose.
antiscorbutics: Refers to herbal medicines that provide Vitamin C.
antisepalous (alt. antesepalous): Opposite the sepals.
antispasmodics: Refers to herbal medicines that can relieve cramping or spasms.
antitumor: Refers to herbal medicines that can prevent or be effective in removing tumors.
antitussive: Refers to herbal medicines that can prevent or ease coughing.
antiviral: Refers to herbal or other medicines that can slow the growth or multiplication of viruses, or kill them.
antrorse: Pointed forward and upward.
aperiodicity: Irregular occurrence of various phenomena, such as leaves dropping out of season (in summer rather than autumn) due to unexpected climatic changes, i.e., storms, droughts, etc. See also: periodicity.
apetalous: Having no petals.
apex: The top or tip of a structure.
aphids: Small, often wingless insects that suck sap.
aphotic: The deep zone of an ocean or lake receiving too little sunlight to permit photosynthesis.
aphotic zone: The deeper portions of bodies of water in which sunlight does not penetrate with enough intensity to cause changes in organisms. See also: disphotic zone, euphotic zone, photic zone.
aphototropism: The response of an organism in turning away from the source of light. See also: photophobic, photomanic.
aphrodisiac: Refers to herbal preparations that can stimulate sexual desire.
aphyllous: Without leaves.
aphytal zone: The deeper portion of a lake bottom that lacks plants, including the sublittoral zone and the profundal zone.
apical (adj. apically): 1. Borne at the tip of an organ, farthest from the point of attachment, e.g., a bud which terminates a stem. 2. Describes the cells composing the apex of the leaf. They are often broader and shorter than the cells of the middle of the leaf.
apical dominance: The ability of the apical meristem to produce hormones to prevent side shoots or buds from developing while it is growing.
apiculate: Having an apicule.
apicule: A short sharp point, not rigid, found at the tip of a leaf, bract, or petal.
apiculum (adj. apiculate): A short, pointed, flexible tip.
apo-: A prefix denoting away from or separate.
apocarpous: With carpels separate rather than united. See also: syncarpous.
apogamous: Developed without fertilization.
apogamy: The formation of a sporophyte from a gametophyte by asexual means such as budding, rather than by sexual fertilization.
apogeotropism: The response by an organism of turning away from the earth, e.g., plant stems growing upward.
apomict (adj. apomictic): A plant that reproduces by apomixis.
apomixis: Reproduction without fertilization or formation of gametes.
apomorphic: Describes a derived characteristic. See also: autoapomorphic, pleisiomorphic, synapomorphic.
apopetalous: With separate petals, not united to other petals; choripetalous.
apophysis: See hypophysis, the more correct term according to Braithwaite.
aposepalous: With separate petals, not united to other petals; chorisepalous.
aposporous: Having the condition of apospory.
apospory: The formation of a gametophyte from a sporophyte by asexual means without meiosis or sporeformation.
apothecium (pl. apothecia): The open fungus fructification, as a cup or disc, lined with asci.
appendage: A structure attached to or arising from a larger structure.
appendiculate: Describes cilia with small transverse spurs attached at intervals along the margin. As these barssometimes extend inward instead of laterally, they are not always visible in a strictly dorsal view.
appendix: The long narrow development of the spadix in Araceae.
applanate: Pressed; flattened.
appressed: Lying close and flat against, as a bud against a twig.
approximate: Located close together and nearly touching.
apron: A layer of hard material like concrete or timber that protects soil from erosion, e.g., pavement at the spillway of a dam.
apterous: With no wings.
apud: The connector term used between names when two authors describe the same species in separate publications, e.g., Ceratozamia latifolia Miq. apud Tijdschr.
aquaculture: 1. The raising of fish or other aquatic animals for their commercial value. 2. Hydroponic horticulture.
aquatic plants (alt. aquatics): Those species whose seeds germinate in water or in bottom soil of bodies of water, usually with submersed or floating leaf types.
aqueduct: A conduit for water, whether canal, pipe, tunnel or a combination of these or others.
aquiculture: The use of artificial reefs and other structures to increase the production of seafood in fresh or salt water.
aquifer (alt. aquafer): A natural holding tank of porous rock or soil locked between impermeable layers in which water may travel long distances.
aquiherbosa: Communities of herbaceous plants growing in ponds and marshes.
aquiprata: Communities of plants where the surface water is a necessary factor, as in wet meadows.
arable land: Land that may immediately be used for farming without clearing trees, draining, etc.
arachnoid (adj. arachnose): A surface with many fine hairs that appears covered with cobwebs.
araneous: Cobwebby.
arbor (alt. arbour): 1. A lattice-covered structure with open sides, usually with vines, such as grapes trained across the top. 2. An orchard or a garden devoted to trees.
arboreal: Of or resembling a tree.
arboreous: 1. Having many trees. 2. Tree-like.
arborescent: Tree-like in appearance and size.
arboretum (pl. arboreta): A botanical center devoted to the study and exhibition of trees.
arboriculture: The cultivation of trees.
arcade: A series of arches with columns or piers; in gardens, usually having trees forming the arched ceiling.
archaeophyte: A plant that existed in prehistoric times.
archegone: The egg cell produced in the archegonium.
archegonium (pl. archegonia, adj. archegonial, adj. archegoniate): The flask-shaped female reproductive organs on the prothallium in the higher cryptogamscorresponding to a pistil in the flowering plants and containing the egg which becomes the sporophyte. See also: antherozoid.
archibenthic zone (adj. archibenthal): The ocean layers between 200 feet and 3300 feet (65 and 1050 m.)l; the upper part of the abyssal zone.
arching: Curved gently outward and then downward; generally said of stems, large leaves, and floral clusters.
architectural: Describes plants that have very strong shapes and are used in landscapes for this reason.
arctic: Describes an extremely cold climate, particularly that of the polar regions.
arctic-alpine: Refers to areas which are mountainous, above the tree line, and north of the arctic circle.
arcuate: 1. Moderately curved. 2. In mosses, refers to a capsule bent in a curve like a bow.
area: The total range in which a taxon or community may be found. See also: basal area, coverage.
areg: A sand desert.
arenaceous: 1. Describes a sandy soil. 2. Growing in sandy soil.
arenicolous: Refers to organisms which live where there is sandy subsoil.
areography: The study that deals with the range of a species. See also: area.
areola (pl. areolae): A space enclosed by anastomosing veinlets.
areolate: Having areolae; marked out into small spaces; reticulate.
areolation: The network formed by the outlines of the cells of a leaf.
areole (adj. areolate): 1. The space between veins of a leaf or a similar partition. 2. A small pit or cavity marked out upon a surface. 3. The area from which hairs, spines, flowers, or branches may arise in Cactaceae.
argillaceous: Like clay, growing in clay, or clay-colored.
arid (n. aridity): Xeric, extremely dry.
aril: A fleshy appendage growing at or about the hilum of a seed.
arillate: Having an aril.
arista (pl. aristae): A bristle-like appendage, like the awn of grasses.
aristate (syn. awned): 1. Describes a leaf which terminates in a stiff, bristle-like tip. 2. Awned; provided with stiffish bristle-shaped appendages.
aristulate: Having a small awn.
armature: 1. The basic framework of an object or organism. 2. A protective covering or other kind of defense, e.g., thorns.
aromatic: Having a spicy odor, at least when crushed.
aromatics: Refers to herbal medicines that have a pleasing odor and pungent taste.
arrangement: A nontechnical term that refers to the way things are put together, e.g., an inflorescence may be described by the arrangement of the flowers, or leaves can be arranged opposite or alternate.
arrhythmic: Refers to activity which is not dependent upon light or dark. See also: diurnal, nocturnal.
arroyo: A watercourse, gully, or channel carved by water, often dry.
ARS: An acronym representing the name the American Rose Society, a nonprofit, educational organization dedicated to the cultivation and enjoyment of roses.
arthropod: Insect, crab, spider, centipede, or other animal from the phylum Arthropoda.
article: A segment of a jointed stem.
articulate (syn. articulated): 1. Having a swollen area, often discolored, at the node. 2. With a joint, often on a zigzag stem.
artifact: 1. A structure or appearance in a tissue due to death or the use of a reagent, and not present during life. 2. A product of human workmanship found on archeological digs.
artificial selection: The intentional human manipulation within a population to produce a desired evolutionary response. See also: natural selection.
artificial stocking: The introduction of animals from another area, such as providing streams with new species of fish or bringing gamebirds into an area where they are scarce.
arundinaceous: Reed-like.
ascending: Rising somewhat obliquely, or curving upward. Ascending ovule: one that is attached above the base of the ovary and is directed upward.
ascogonium: The special hypha from which the fertile hyphae develop to produce asci.
ascomycete: A fungus producing asci.
ascus (pl. asci): The reproductive cell (meiotangium) of a fungus containing usually eight ascospores.
asepalous: Without sepals.
aseptate: With no partitions or divisions.
asexual: Lacking sexual characteristics as in a sterile ray floret; or when referring to reproduction, occurring without the fusion of egg and sperm.
asexual propagation: The propagation of plants through means other than fertilization, including layering, cuttings, tissue cultures, and the division of clumps.
asexual reproduction: Not involving or requiring fertilization and meiosis.
ashlar: 1. Dressed, finely-jointed stonework, usually having a polished surface and sometimes consisting merely of a facing for a wall of rubble or brick. 2. The stones used in this stonework.
aspect: 1. The appearance of vegetation during one of the seasons of the year, e.g., the vernal aspect. 2. The direction toward which a slope is facing, e.g., the southern aspect.
aspection: The change in the appearance of vegetation and its visible attributes during the succession of seasons of the year, as budding in prevernal, flowers in vernal, green fruit in estival, ripe fruit in serotinal, and bare branches in hibernal.
asperous: With a rough surface.
asperulate: Somewhat rough to the touch.
asperulous: Refers to a surface with short, hard projections.
assimilation: Cellular conversion of raw materials into structures useful to a plant, such as cell walls and protoplasm.
association complex: A group of associations which occurs in a defined area.
association fragment: A stand of plants that requires other characteristics to meet community standards.
association segregate: A climax community which has changed from the original community, like a mature beech-maple association appearing from a mixed deciduous forest.
association table (syn. synthesis table, syn. stand table): A list of species that occurs in several stands of an association or community, including data on characteristics such as abundance, cover, vitality, etc.
associes: A temporary community in developmental stage.
assortative breeding (syn. assortative mating): The pairing of male and female organisms in a manner that involves more than chance, so that the mating of similar parents is encouraged.
assurgent: Ascending.
asterean: Belonging to or similar to plants of the aster family, Compositae.
astomous: In mosses, refers to a capsule without a mouth. Used of capsules which have no regularly dehiscent lid or operculum.
astragaloid: Cubical.
astringent: An herbal preparation that shrinks and firms tissue, particularly the skin.
astylous: Lacking a style.
asymmetrical: Having a different shape on each side of a central axis.
asymptotic population: The maximum size possible to a population under present conditions, no matter how long reproduction is allowed to continue.
atavistic: Reverting to a form found in ancient ancestors.
atmometer: Any instrument for measuring evaporation like a porous sphere or open pan of water.
atoll: A circular coral island or islands surrounding a body of water in the ocean. See also: lagoon.
atrocastaneous: Very dark chestnut in color.
atrophy (adj. atrophied, alt. atrophic): 1. A wasting away from lack of nutrition or use. 2. Arrested development of a part or organ inconsequential to the normal development of a plant or animal.
atropurpureus: Colored deep purple, almost black.
attenuate: A long gradual taper, as at the base or tip of a leaf or flower parts, drawn out into a long point. See also: acute.
atypical: Not normal.
auctoris (alt. auctorum, abr. auct., abr. auctt.): Used in taxonomy when an author has applied a wrong name, usually beginning with "non," to contrast it to the true type with the correct author, e.g., Betula platyphylla auct. Non Sukachev, which is in fact a different plant, Betula mandschurica.
auger: A T-shaped tool, like a large corkscrew, used for drilling holes in the soil.
auricle: An ear-shaped appendage.
auriculate: Shaped like an ear.
auriculiform: Having the shape of an ear.
aurieles: Small lobes at the basal angles of the leaf, usually consisting of cells differing in size, shape, or both from those of the main part of the leaf. Properly used only when there is an outward curve in the outline of the leaf at the base, but often used loosely to denote the basal angles of widely decurrent leaves.
auroral: Refers to morning, the crepuscular period, or dawn.
autapomorphic: Describes a derived characteristic unique to a given taxon or monophyletic group. See also: apomorphic, synapomorphic.
autecology: The study of the individual in relation to environmental conditions, or sometimes, members of a speciesstudied collectively in the same way.
author: 1. The botanist who discovered and named the new taxon. 2. The name or initial(s) following the taxon name, designating that botanist.
autochore: A species in which some action of the parent plant is the chief force for dissemination, e.g., the mechanical projection of seeds in jewelweed, Impatiens.
autochthonous: 1. Describes the original or earliest known inhabitants of a region. 2. Originating in the place where found; indigenous. 3. Originating from within a system, such as organic matter in a stream resulting from photosynthesis by aquatic plants. See also: allochthonous.
autoecious (alt. autocious): 1. Refers to parasites which pass all stages of their life cycle on or within the same host, like certain rustfungus. 2. Having male and female organs on the same plant. See also: heteroecious.
autogamous: Self-fertilizing.
autogamy: Where male parts can fertilize female parts of the same flower through self-fertilzation or hermaphroditism; inbreeding.
autogenic succession: Vegetational progression in which each stage modifies the habitat in such a way that it is replaced by another stage, e.g., pond shoreline herbaceous plants being replaced by shrubs.
autolysis: The digestion of an organism or parts of it by its own enzymes.
autonomic: Refers to processes or activities that are spontaneous, arising from internal causes. See also: autonomous.
autonomous: 1. Autonomic. 2. Refers to plants, especially those with chlorophyll, that are capable of turning inorganic materials to organic ones for their nutrition or other use. See also: autotrophic, photosynthesis.
autonym: When an author names a new subspecies or variety, the species is given the same new rank, based on the original type of the species and duplicating the epithet, e.g., when Pinus nigra ssp. larico was designated, Pinus nigra ssp. nigra came into being.
autopolyploid: An organism or cell which contains three or more sets of homologous chromosomes that developed from the same species. See also: amphiploid, allopolyploid.
autotrophic (n. autophyte): 1. Refers to organisms that are capable of processing inorganic materials into organic ones by using energy from outside the organism such as sunshine on chlorophyll. 2. Refers to a body of water that is limited in its supply of organic material to what it is capable of producing within its own borders.
autumnal (syn. fall): Refers to the season between summer and winter that, in the northern hemisphere, includes the months of September, October, and December. Astronomically speaking, it is the period extending from the September equinox to the December solstice.
auximone: A nonessential organic substance of unknown chemical composition, which produces a known reaction, such as growth of duckweed, Lemna, from an extract of dung.
auxin: One of several hormones occurring in plants which regulates certain aspects of growth. They can be produced synthetically and are sometimes used commercially as herbicides or to promote flowering or other types of plant growth.
auxospore: A cell that restores the original size to the diminishing products of cell division.
auxotelic: Describes an inflorescences, parts of inflorescences or axes that do not end in a flower, and in which growth continues beyond the flowering region, See also: anauxotelic.
available nutrient: The portion of nutrient substances, such as nitrates in the soil, that can be utilized by plants at rates and amounts required for growth.
available water: That portion of water held in soil that may be absorbed into the roots of the plant.
available water-holding capacity: The amount of water in soil that can be absorbed by plants, between the high amount at full saturation or field capacity, and the low amount at the permanent wilting capacity.
avalanche: A large mass of snow, ice, rocks, trees, etc., in swift descent down a mountain or over a precipice.
avalanche cone: All the materials left at the base of a slope following an avalanche.
avalanche wind: Moving air stirred up by an avalanche and often destructive over considerable distances.
avenue: A path or road lined with trees on both sides, usually all of the same type.
average distance: The mathematical statement of the distance between plants calculated by dividing the square root of an area by the density of each species within the area.
avitaminosis: Reduced health from deficiency of vitamins.
awl-shaped: Tapering upward from the base to a slender or rigid point.
awn: A bristle-shaped appendage, especially on grass seeds or grains.
axe: A waist-high tool with a vertical, sharpened, narrow wedge head for cutting wood.
axe-shaped: Dolabriform; describes three-dimensional shapes.
axial: Refers to the main line or trunk of the entire plant, the specific branch, the inflorescence, etc.
axil: The angle formed by a leaf or branch with the stem.
axile: Belonging to, or found in, the axil.
axillary: Situated in an axil.
axis: The main line of growth in a plant or organ, e.g., the stem, from which the other parts such as the leaves and flowers grow.
azonal: Refers to soil that has no well developed profile with horizons, such as glacial deposits, dune sand, alluvium.
B horizon: The soil layer between A and c horizons, in which materials from overlying horizons accumulate from precipitation or suspension.
baccate: Berry-like; pulpy throughout.
bacciform: Berry-shaped.
bacilliform (syn. baculiform): Rod-shaped.
Bacillus thuringiensis (abr. Bt): A bacterium which is lethal to some insects and is used as a biological control.
backbulb: A dormant water-storing thickened stem that looks like a bulb, found in Orchidaceae. It grows actively as a pseudobulb the first year, then becomes dormant when the next year's pseudobulb takes over.
backcross (alt. back cross): 1. To cross a first-generation hybrid with one of the parental types. 2. The offspring of a cross between a hybrid and one of its parents.
backfill: Earth used to fill trenches or holes, often the same soil that was removed to make the hole.
backfire: A fire purposely set ahead of an advancing fire to destroy flammable materials, enabling workers to control the main fire.
backflash: Movement of a poison through natural root grafts, from trees that have been treated with poison, back to non-treated trees.
backshore: That part of the beach from the first crest toward the land.
bactericide (alt. bactericidal): Something, such as an herbal preparation, capable of destroying bacteria.
bacteriophage: A virus which destroys bacteria.
bacteriorhizae: Nodules on the roots of most legumes and a few other plants, which contain bacteria that uses atmospheric nitrogen to synthesize organic compounds.
baculiform (syn. bacilliform): Rod-shaped.
badlands: Regions of eroded land on which most of the surface is covered with ridges, gullies, and deep channels, having sparse vegetation.
Baermann funnel: A modification of the Berlese funnel, used to force nematodes out of soil or debris by filling the funnel with warm water, driving the nematodes into a vessel below.
baffle-pier: A blockage placed in the path of high-velocity water, like a pier on the apron of an overflow dam.
baffles: Vanes, guides, or other devices inside a conduit to check eddy currents below them, and provide more uniform distribution of sp.ed.
bagasse: Residue of sugarcane after the juice has been extracted.
baguio: A term used in the Philippine Islands for a tropical cyclone or typhoon.
bajada: A term used in the southwestern united States to describe outwash slopes with long straight profiles.
balance of nature (alt. ecological balance, alt. biotic balance, syn. dynamic equilibrium, syn. biotic equilibrium): A term for an ideal condition in which the interrelationships of organisms to one another and their environment appear harmonious, like a climax forest. In reality, the balance is continually upset by natural events.
balanoid: Refers to barnacles.
bald: A treeless region in forest vegetation; perhaps an area of grasses or shrubs in southern Appalachia, or a mountaintop.
balled and burlapped: Taken out of the ground with a ball of soil around the roots and then wrapped in burlap for support.
balling: A condition where outer petals stick together and fail to open, often occurring in damp weather.
ballistic: Refers to fruits that discharge their seeds forcefully; catapult fruits.
bamboo: Any of various usually woody and/or arborescent grasses of the tropical or temperate regions belonging to the genera Bambusa, Arundinaria, Phyllostachys, Sasa, Dendrocalamus, etc., most having hard, hollow stems.
banados: Shallow swamps in Paraguay.
Bancroft's Law: A generalization that organisms and communities tend toward a state of dynamic equilibrium with the environment.
bank storage: Water absorbed by the bed and banks of a stream, returned in whole or part after ground water level falls.
bar: 1. A continually moving deposit of sand forming a ridge along the seashore or the coasts of large lakes. 2. A unit of atmospheric pressure equivalent to 29.53 inches (750.1 mm) of mercury at 32 degrees at latitude 45 degrees.
barachore: A species in which the fruit or seed is desseminated by its own weight, e.g., walnuts, Juglans, falling to the ground. See also: autochore, diaspore.
barbed: Furnished with rigid points or short bristles, usually reflexed like the barb of a fish hook.
barbed trichome: A trichome with terminal or lateral retrorse projections, each projection being a barb.
barbellae: Short, stiff barbs.
barbellate: Finely-barbed.
barbulae: Outgrowths on the margin of the wings or in the throat of the corolla, sometimes with apical hairs or papillae (found in plants of the genus Scaevola.)
barbulate: Finely-bearded.
barchan: A distinctive isolated, crescent-shaped, sand dune with the ends projecting on the side opposite that from which the wind blows, common in Turkestan.
bare-root: Describes a plant that is prepared for transporting by removing all the soil around its roots.
bark: The outer covering of the trunks or branches of trees and shrubs.
bark-cambium: The layer of cells that produces new bark.
barogram: A continuous record of the readings of a barograph.
barograph: A self-registering barometer.
barotaxis: Response of an organism in response to barometric stimulus.
barotropism: Change of position of a plant or sedentary animal in response to a barometric stimulus.
barrens: A region where vegetation is absent or poorly developed.
barrier: 1. Any feature or condition that restricts movement of organisms or prevents establishment of organisms which have migrated there. 2. A condition that prevents or significantly reduces crossbreeding of organisms.
barrier beach: A strip of land built up by the action of waves, currents and winds, and which protects inner areas.
basal (alt. basilar): 1. Growing from the base of a stem; used in reference to leaves at the base of the stem. 2. One of the main canes of a rose bush, originating from the bud union. 3. Describes cells at the base or insertion of the leaf, often of different shapes and colors from those of the main part of the leaf.
basal area (alt. basal cover, alt. ground cover, alt. cover): 1. The area of the cross section of a tree at a height of 4.5 feet above the ground, generally written as the total of the basal area of the trees in a forest in square feet per acre. 2. The surface of the soilactually covered by a plant, as compared to the full spread of the herbage, which in grassland ecologyoften measures at one inch above the ground.
base: The proximal portion of a structure; that part nearest the point of attachment.
base exchange capacity: A measure of the absorptive capacity of a soil for materials with exchangeable cations, a nonacid reaction. A soil with a high base exchange capacity will retain more plant nutrients and is less apt to leach than one with a low exchange capacity.
base flow: Springs; stream flow coming from subterranean sources in contrast to surface runoff.
base level: The lowest level to which a land surface can drop by action of water; the permanent base level is sea level.
base saturation: The proportion of the base exchange capacity that is saturated with metallic cations.
basidiomycete: A fungus-producing basidia.
basidium (pl. basidia): The reproductive fungus cell (meiotangium) producing usually four spores on the outside.
basifixed: Attached by the base.
basin irrigation: An artificial method of watering plants in which a level field is surrounded by a ridge of earth so that a shallow body of water may accumulate before it soaks into the soil.
basin listing: A way of working land by constructing small dams at intervals across furrows to form basins for collecting rainwater, slowing runoff and erosion.
basionym: A specific or infraspecific name which has priority over other names later given to the same plant by different authors. See also: synonym, homonym, tautonym, autonym.
basipetal (adj. basipetalous): Developing from the apex towards the base. See also: acropetal.
basiscopic: Facing the base of the axis on which it is borne.
basitonic: Describes flowering seasonal shoots which produce no leaves (except for bracts in some cases) below the inflorescence. See also: acrotonic.
basophilous: Refers to organisms which have adapted for life in alkaline soil or other medium.
bast: The fibrous portion of the inner bark.
bathyal zone (adj. bathyic): The deep part of the ocean where light does not penetrate sufficiently for normal plant growth.
bathypelagic: Refers to deep parts of the ocean, but not including the ocean bottom.
bathyphyll: A modified leaf which attaches a plant to a substrate.
bathysphere: A pressure-resistant underwater structure with a spherical chamber in which scientists can descend deep into the ocean.
batten: Lath, often wired together as in snow fencing.
batten stripping: Plastic strapping which can be used in a manner similar to snow fencing.
bay (alt. embayment): A notch in the shoreline, not restricted to any single form. It may be a lobe of water extending inland as deeply as a firth or fiord, or it may be as shallow as a quarter moon shape. See also: cove.
bayou: A creek or slow-moving stream.
beach: Where water meets land at the edge of lakes, oceans, etc. A barrier beach is a ridge of sandy deposits separated from the mainland by a section of water. See also: atoll.
beach pool: The barrier beach pool is a shallow lagoon formed inland from the barrier beach. 2. A sand spit beach pool is a shallow lagoon, generally S-shaped, that is inland from a sand spit, most often on the protected side of a headland.
beak: Prolonged narrow tip of the operculum.
beaked: Ending in a prolonged tip.
bearded: Bearing a long awn, or furnished with long or stiff hairs, as seen on the lower petals of some irises.
Beaufort scale: An artificial number scale invented by Francis Beaufort in 1805 to show approximate wind sp.edranging from 0 miles per hour (mph) for calm to 12 mph for a hurricane velocity in excess of 75 mph.
Beckmann thermometer: A thermometer for a narrow range at very accurate readings, such as one graduated to 0.01 degrees for a range of 7 degrees.
bed load: Rocks, sand, gravel, and other debris rolled along the bottom of a stream by high-velocity water, in contrast to silt load, which is suspended in place.
bed preparation: Mixing compost, ashes, and/or sand with natural soil to improve growing potential.
bedding plants: Plants used in large numbers in usually temporary displays. Most often annuals, tender perennials, and bulbs not able or intended to naturalize and which are grown indoors or under glass before planting.
bedrock: The layer of solid rock underlying a soil profile or other surface materials.
belly plants: A humorous term for inconspicuous plants, which often require botanists to crawl on their bellies to find them.
below: Refers to the position of one portion of an organ or plant in relation to another portion; the part "below" is the nearest to the attachment. See also: above.
belt: A long narrow area or strip of vegetation with characteristics which define it from adjoining areas.
belt transect: A type of vegetational analysis in which a portion of land a few inches or a few feet wide, and often a meter wide and 10 to 100 meters long, has constituent plants recorded.
bench mark: The point of reference in elevation surveys from where surveyors start to furnish an accurate survey.
bench terrace: A shelf-like embankment of earth, usually man-made, along a contour of sloping land to control runoffand erosion. See also: ridge terrace.
benthic: Refers to the bottom of any body of water, regardless of depth. Oceanic benthic division is composed of littoral, sublittoral, archibenthic, and abyssal-benthic zones.
benthos: Organisms which live on or at the bottom of oceans or fresh water, from the water's edge down to the deepest water depths. See also: nekton.
bentonite: Absorptive and colloidal clay used as a sealing agent, as in lining ponds.
Berlese funnel: A device in which soil is placed, and heat and light are applied from above, forcing mites, collembolons, etc., into a container below it. See also: Baermann funnel, Tullgren funnel.
berm (alt. berme): 1. A narrow shelf, path, or ledge typically at the top or bottom of an escarpment or beside a road. 2. A mound or wall of earth.
berry (pl. berries): A fleshy fruit that contains small seeds, the whole pericarp of which is fleshy or pulpy.
betacyanin: The nitrogen-based red pigments of beets, Beta spp., and other Chenopodiaceae, as well as flowers of Cactaceae, Portulacaceae, and others.
biannual: Occurring twice a year. See also: biennial.
biauriculate: Having two auricles.
biblical garden: A botanical area consisting of plants mentioned in the Bible.
bibracteolate: Having two bracteoles.
bicalcarate: Having two spurs.
bicallose: Having two callosities.
bicarinate: Having two keels.
bicarpellate: Having a two-celled fruit.
bicentric: Refers to a taxon which has two centers of dissemination or evolution.
bicolored (alt. bicolorous): Having two colors on the same structure, often said of petals.
biconvex: Bulging outward on both sides, almost a sphere or orb.
bicornute: Having two horns.
bicostate: In mosses, having a double costa, which is usually much shorter than in leaves having a single costa.
bicrenate: Biserrate with both sets of teeth being shallow and rounded.
bidentate: Having two teeth.
biennial: A plant with a life cycle that is completed in two years or seasons, with the second season usually devoted to flowering and fruiting.
bifacial: Refers to leaves with distinct adaxial and abaxial surfaces.
bifarious: Growing in two ranks, such as needle-type leaves growing in two rows on opposite sides of a twig; distichous.
bifid: 1. Cleft into two parts. 2. Divided into pinnae-bearing pinnules.
biflorus: Refers to a plant which flowers in both spring and autumn.
bifoliate: Having just two leaves.
bifoliolate: Having just two leaflets per leaf.
bifurcated: Forked or divided into two parts.
bigeminate: In two pairs; used in describing pinnate leaves which have only two pairs of pinnae.
bigeneric: A hybrid produced by crossing parents from two genera.
bilabiate: Two-lipped.
bilamellate: Made up of two plates.
bilateral symmetry: Describes flowers that can be divided into two equal halves by only one line through the middle.
bilocular: Two-celled.
binary fission: The division of a single-celled organism into two daughter cells.
binate: Growing in pairs.
binder: Hardened cement paste.
binder twine: Coarse jute or plastic cord for baling hay or tying bundles of wheat or other grain. See also: nursery jute.
binomial (syn. binary name, syn. binary combination): A name consisting of two parts, the first being the genus and capitalized, the second being the speciesand usually lowercased initial with both names being italicized, e.g., Gypsophila elegans.
binomial nomenclature: The use of the genus and species names together to identify a given organism in the taxonomic system.
bioassay: Determination of relative strength of a substance by testing on an organism.
biocenose (alt. biocoenose, alt. biocoenosis): All of the interacting organisms living together in specific habitat, usually containing producer, consumer, reducer, and transformer types. See also: ecosystem, community, association.
biochemical oxygen demand (abr. B.O.D.): A test to detect and measure pollution in water by determining the quantity of oxygen already used up by oxidizable materials.
biochore: A subdivision of the biocycle which contains a group of biotopes which resemble one another; habitat. Examples are grassland, forest and desert.
bioclimate: Microclimate.
bioclimatic law (syn. Hopkins' law): The generalization that in temperate North America, weather-related events, such as bloom time, can be determined to be similar as you move up or down a mountain 400 feet, or one degree of latitude, or 5 degrees of longitude. In the spring, each of these measurements are eastward or upward and are four days later; in autumn, they are westward or downward and are four days earlier.
bioclimatology: The study of interrelationships between living things and the climate.
biocoenology (alt. biocoenotics): The study of communities including qualitative and quantitative analyses.
biocycle: A subdivision of the biosphere, including saltwater, freshwater and land. Each consists of biochores. See also: biotope.
biodemography: Numerical and mathematical treatment of population problems.
biodiversity: The totality of genes, species, and ecosystems in a specified area, or the entire world.
biodynamic: Relating to a system of farming that uses only organic materials.
bioecology: A branch of biology treating interrelationships of both plants and animals among themselves and with their environment. See also: ecology.
biogenesis (adj. biogenic): The principle that plants or animals can originate only from other plants or animals. See also: spontaneous generation.
biogeocenose: A specific ecosystem unique to a designated geographic area.
biogeochemical cycle: The circulation of chemical elements (e.g., oxygen, carbon, etc.) from the environment into plants and animals and back again into the environment.
biogeographic region: A biome.
biogeography: The branch of biology that treats the latitude and longitude of the location of plants and animals; range. See also: chorology.
biointization: The chemical treatment of seeds to stimulate growth.
biological clock: The rhythmic repetition of processes in organisms, like the need for sleep in mammals.
biological control: The use of living things to control pests, such as the control of aphids by lady beetles; integrated pest management.
biological efficiency: The ratio of the productivity of an organism or community of organisms to that of its supply of energy. A black bear would have a much higher efficiency hunting in the summer than in winter, so it is more efficient to hibernate during the winter months.
biological equilibrium (syn. biotic balance, syn. balance of nature): The state of natural control, self-regulation of the numbers of plants and animals in a community, brought about by interactions within and between plants and animals and the effects of environmentsuch as weather. For example, as the numbers of white-footed mice, Paramyscus, rise, grass seeds, Graminae, decrease and the numbers of foxes, Vulpes, increase. See also: life cycle, pyramid of numbers.
biological factor: An influence that results from biological agents, including biotic factors such as lack of sunshine and physiologic factors like hormones. For example, death rates of white-tailed deer, Odocoilus, increase along highways during rutting season at night.
biological race (syn. biological strain): A group of organisms which differ only in their physiological or ecological behavior from other groups in the same species, e.g., woodland white-footed mice, Paramyscus, run in straight lines where meadowwhite-footed mice run zigzag lines.
biological resources (syn. biotic resources): The factors of biodiversity which are of direct, indirect, or potential use to humanity.
biological spectrum: A percentile tabulation of the plants of a community into the life form classes according to Raunkiaer's classification.
biologics: Biological products such as vaccines.
biology: The study of living organisms.
bioluminescence (syn. phosphorescence): The emission of light by living organisms such as fireflies and jellyfish.
biomass: The total mass of all living organisms in a given area.
biome (syn. biotic formation): The ecology of a particular habitat, characterized by its unique plant and animal symbioticrelationships, and maintained by local climatic conditions.
biome-type (syn. biorealm): A group of similar biomes, such as the temperate deciduous biome-type which includes all the deciduous forests of eastern North America, China and Manchuria, and Europe.
biometry: The statistical study of organisms.
bionomics: The study of the relationship of organisms to each other and their environment. See also: ecology.
bioregion: An area defined by social, biological, and geographic criteria, rather than geopolitical jurisdictions.
bioregional management (syn. bioregional planning): Directional supervision over an area of similar habitat rather than by standard state/county lines, e.g., cooperative public, private, and business environmental planning for a major watershed such as Chesapeake bay.
bios: Plant and animal life.
bioseston: All living components of the seston.
biosphere: That part of the earth and its atmosphere that can support life.
biosynthetic (n. biosynthesis): Describes a chemical compound produced by a living organism.
biosystem: Ecosystem.
biosystematics: The classification of living organisms that recognizes and differentiates biotic units into taxa on the basis of genetic relationships.
biota (syn. flora and fauna): All of the living things, including animals, plants, fungi, and microorganisms, located in a given area.
biotechnology: Applied biological science, especially in genetic engineering and DNA technology.
biotic: Refers to any aspect of life, but especially to characteristics of entire populations or ecosystems.
biotic area (syn. biotic region): A general term delineating any large area from adjacent areas on the basis of the composition of its biota.
biotic climax: The type of community capable of lasting for long periods of time under the present soil and climate conditions, in combination with the animals living there, including humans. See also: edaphic climax, physiographic climax, sere.
biotic environment: All living things found in the environment of an organism or community.
biotic factor (syn. biological factor, syn. biotic influence): Environmental influences caused by plants or animals like shading or trampling. Sometimes used so nonliving effects are included, like landslides. See also: coaction.
biotic potential (syn. reproductive potential, syn. breeding potential): The natural capacity of an organism to survive and reproduce, which is slowed or controlled by environmental resistance.
biotic pressure: The tendency of a species or community to extend its range.
biotic province: A major ecological section of a continent containing one or more regional communities of plants and animals. See also: biome, formation.
biotin: 1. A substance which promotes or stimulates growth and repair. 2. One member of the Vitamin B complex.
biotope: A region environmentally uniform in conditions and in the flora and fauna which live there.
biotrophic: Describes an organism which cannot survive or reproduce unless it is on another organism.
biotype: 1. A group of organisms sharing a genotype. 2. A particular physical characteristic distinguishing a population of an organism adapted to a particular environment which does not occur in populations of the same species in other environments.
biovulvate: Having two ovules.
bipartite: Divided into two parts almost to the base.
bipinnate: Twice pinnate; the primary leaflets being again divided into secondary leaflets. See also: bipinnatifid.
bipinnatifid: Twice pinnatifid. See also: bipinnate.
bipinnatisect (alt. 2-pinnatisect): Refers to a pinnately compound leaf, in which each leaflet is again divided into pinnae.
bipolar distribution: Refers to a taxon present in both the northern and southern hemispheres with no apparent connection between populations.
Birge's rule: A generalization theorizing that the thermocline is the transition layer in lakes in which the temperature decreases at a rate of one or more degrees for each meter in depth.
bisect: A line transect which shows the vertical and lateral distribution of roots at the walls of a trench with the above-ground parts of plants along the verge.
bisected: Completely divided into two parts.
biseptate: Having two partitions.
biseriate: Arranged in two rows.
biserrate: Refers to a serrate border where the principal teeth are serrated.
bisexual: A flower having both stamens and pistils. See also: synoicous.
bistratose: Having two layers of cells.
biternate: Twice ternate; with three pinnae each divided into three pinnules.
bitten: Praemorose, with ragged edges as though chewed.
bivalent: A pair of chromosomes, usually one from each parent.
bivalvular (alt. bivalvate): With two valves.
bivoltine: Refers to organisms which produce two generations each year, like raspberries, Rubus, which produce fruit in late spring and fall.
black alkaline: Soil with a pH well over 7.5, covered with a dark crust of sodium or potassium carbonates.
black spot (alt. blackspot): A fungus appearing as large, fuzzy black spots on rose leaves, especially in wet weather.
blacktop: Asphalt surfacing used for driveways, paths, and roads.
bladdery (alt. bladder-like): Inflated, with thin walls like the bladder of an animal.
blade: The expanded portion of a leaf, frond, etc.
blanching: Excluding light from the green parts of plants so that they become white and tender; etiolated.
blast: Injury caused by disease or conditions such as hot winds that shrivel buds, branches, etc.
bleed: To have water seep to the surface of cement paste due to settling.
blend: Two or more colors which gradually merge but are distinguishable from a distance of six feet (used in describing dahlias.)
blight: 1. A disease of plants resulting in withering, cessation of growth, and death of parts, especially young tissue. 2. An organism that causes blight, such as a bacterium, fungus, or virus.
blistered: Where the surface of an organ is puckered, the veins being tighter allowing the tissue to round up.
blizzard: A storm in which high winds drive fine snow and ice crystals, reducing visibility.
bloom: 1. A flower or blossom. 2. A whitish, powdery, or waxy covering.
blossom: The flower, often applied to fruit trees.
blown: 1. Past tense of to blossom; already opened, as in a full-blown rose. 2. No longer viable, perhaps from drought or disease, as "blown buds of barren flowers."
blowout: A wind-blown excavation in loose soil.
blunt: Not pointed.
boat-shaped: Carinate, cymbiform, navicular.
bob-back: To severely dehorn or damage woody plants while attempting to prune, without understanding the process.
bog (adj. boggy): 1. An area of little or no drainage acidified by rotting vegetation, often with some open water surrounded by a floating mat of sedges, ericaceous shrubs, acidophilous species, and sphagnum mosses. A quagmire, which trembles or gives way underfoot. 2. Loosely, and not technically correct, a marsh, swamp, moor, fen, muskeg, or heath.
bog soil: A mucky or peaty surface horizon with a peat underlayment.
bole: 1. The trunk of a tree below the first major branch. 2. The crisscrossed bases of palm leaves.
bolson: A depression lacking above-ground drainage in an arid or semiarid region, a term primarily used in Mexico and southwestern U.S.
bolt: To produce flowers and seeds prematurely.
bomb: A pressurized can of insecticide or other compound.
bonitation (alt. ecological bonitation): The state of well being in a population, reflected by increasing numbers of individuals.
bonsai: 1. The art of growing miniaturized trees or shrubs trained for aesthetic effect. 2. A plant grown in such a way.
bonsai scissors: A cutting tool with large handles and small, very sharp, blades.
bool and clay: A rough form of masonry using locally available, uncut stone and clay mortar.
border dike: Man-made ridges of earth to hold irrigation water within certain limits in a field.
border fork: A heavily-constructed garden tool that is shaped like a fork with round tines and is used for digging in garden borders and flower beds.
border irrigation: Flooding fields by the use of border dikes.
border strip: A demarcation surrounding a plot, usually given the same treatment as the plot.
bordered: Having a margin different from the rest of the leaf.
bore: A tidal wave with a forward wall of water three feet (one meter) or more in height, advancing upstream in a narrow river estuary.
boreal forest: A forest made up mostly of conifers, such as that reaching across North America from Newfoundland to Alaska.
boreal period: The climatic period from about 7500 to 5500 B.C., typified by warm dry conditions.
borer: An insect larva that tunnels into stems and trunks of shrubs, trees, etc.
bosket (alt. bosquet): A small park or block of woodland with pathways, usually planted with small, understory trees, and often having statuary and waterworks.
bossed: With a conical protrubence rising from the center of a surface, like the bump on a scale of a pine cone.
bostryx (pl. bostryces): A one-sided helicoid cyme.
botanical: Of or relating to plants or botany.
botanical garden (alt. botanic garden): A garden devoted to the culture, study, and exhibition of plants.
botany: 1. The scientific study of plant life. 2. A botanical treatise or study.
botrytis: A group of fungi that causes plant diseases. 2. The disease caused by such fungi.
bottom deposits: Those materials composing and overlaying the original basin or channel floor of a waterway.
bottom water: To pour water into a saucer underneath a container of a houseplant or jardiniere, allowing the soil to absorb the amount needed. This is often done on plants whose leaves are harmed by water spots, such as African violets, Saintpaulia spp. Generally any excess is poured off after an hour.
bottomland: Flood plain; rich deposits of loam left from flood water runoff.
botuliform: Sausage-shaped.
boulder clay: Unstratified intermix of clay and stones deposited by glaciers. See also: till, drift.
bouquet: 1. Flowers picked and arranged in a bunch. 2. A distinctive fragrance.
brachyblast: A short branch or shoot.
brachypterous: Refers to organisms with short wings.
brackish: 1. Somewhat salty, as water in saline soils or at the union of a river with the ocean. 2. Less correctly, nonsaline water that is distasteful or nauseous because it is stagnant, etc.
bract: 1. A more or less modified leaf subtending a flower or belonging to an inflorescence, or sometimes cauline. 2. The similar structure in cryptogams surrounding reproductive organs.
bracteal: Of or pertaining to the bracts.
bracteate: Having bracts.
bracteolate: Having bractlets.
bracteose: With numerous or conspicuous bracts.
bractlet (syn. bracteole): A secondary bract, as one upon the pedicel of a flower.
brambles: Plants of the genus Rubus, Rosaceae family, usually prickly and bearing fruit, e.g., raspberries and blackberries.
bran: The edible broken seed coats of cereal grain, often separated from the flour or meal by sifting.
branch: A secondary woody stem growing off of the trunk or main stem of a woody plant.
branchlet: Except for the twig, the youngest and smallest division of a branch.
breccia: Rock composed of angular, often crystalline, pieces in a matrix.
breeder: A person who applies genetics and other sciences in the orderly practice of improving a taxon.
bristle (adj. bristly): A hair-like prickle.
broad base terrace: An embankment built to carry runoff water along a contour, usually with a rounded crown 15 to 30 feet (5 to 10 meters) wide, with gently sloping sides and a dished channel along the top.
broad-leafed (alt. broad-leaved): Refers to a plant which does not have coniferous needles or grass-like leaves.
broadcast seeding: Sowing across large areas by scattering seed mechanically or by hand.
broadleaf (alt. broad-leaved): Having broad leaves, rather than needle-like or scale-like ones.
broadleaf evergreen (alt. broad-leaved evergreen): An evergreen plant that is not a conifer.
brochidodromous: Describes leaves with pinnate venation in which the secondary veins do not terminate at the marginsbut rather are joined in a series of prominent arches. See also: acrodromous, eucamptodromous, semicraspedodromous.
bromeliad: Any of the mostly epiphytic herbaceous plants of the family Bromeliaceae found primarily in the tropical and subtropical regions of the Americas, including the pineapple and Spanish moss.
broom-like: Having many parallel branches.
brown earth: 1. Any of a group of intrazonal soils developed under deciduous forests. 2. Soils needing replanting or restoration, especially damaged wetlands.
brown forest soils: Those soils with dark brown surface horizons, but becoming lighter-colored beneath. They are rich in humus and are neutral to slightly acidic in composition, commonly appearing under deciduous forests that are quite rich in calcium or other bases. See also: brown soils.
brown podzolic soils: Those soils with thin layers of partly decayed leaves over a gray-brown layer of mineral matter and humus that covers yellow or yellow-brown acid B horizons. These appear under deciduous or mixed forests in cool, humid, temperate regions.
brown soils: Those soils with brown surface horizon, becoming lighter in color with depth. Calcium carbonate appears at one to three feet. These develop under grasslands and shrubs in temperate to cool semiarid climates. See also: brown forest soils.
Brownian movement (alt. Brownian motion): A condition discovered by Scottish botanist, Dr. Robert Brown (1773-1858), in which rapid vibratory movement of microscopic particles holds the particles and others suspended in a fluid. See also: colloid.
browse: 1. Food for livestock or wild members of the extended deer family, Cervidae, consisting of woody twigsand shoots, with or without leaves. 2. To feed on those plants.
browse line: A condition found in forests or brushland with an over population of browse animals like deer or goats, all branches and twigs eaten as high as the animals can reach.
brush: 1. A thicket of shrubs, small trees, etc. 2. Branches lopped off trees.
brush matting: 1. A covering of branches spread on eroded land to conserve water and lessen erosion that helps establishes trees and other permanent vegetation. 2. A covering of mesh wire along streambanks that holds brush in place to retard erosion.
brush pasture: An area with a natural cover of woody plants, set aside for foraging by goats or other animal browsers.
brushland: An area with shrubs and little other vegetation.
bryophyte: A plant in the botanical division Bryophyta, which includes mosses and liverworts.
bud: The rudimentary state of a stem or branch; an unexpanded flower.
bud eye: A dormant bud in the axil of a leaf, used to propagate through bud-grafting.
bud union (alt. budding union): The junction on a stem, usually swollen, where a graft bud has joined the stock following the process of budding. Usually found at or near soil level.
bud-scale: A modified leaf, without lamina, protecting a bud.
budded: Grown from a bud grafted onto a desirable understock.
budding (n. bud graft): Method of propagating woody plants. A cutting of one variety, called the scion, with bud(s) attached is joined onto another related species or variety, called the stock. As the tissues grow together a singleplant is formed with top-growth of the scion on the base of the stock.
buffalo wallow: An area in a grassland where large grazing animals have rolled, usually because of biting flies, killing the grass and losing soil.
buffer species: A plant or animal which may serve as an alternate food supply for a consumer animal, lessening the demand for a more desirable food species.
buffer strip: A transect of grassland or other erosion resistant vegetation located between or below cultivatedlengths or fields.
buffer zone: 1. A strip that partially or fully encloses a study area or other designated area to protect the inner section from ecological disturbance by outside pressures; a transition zone between districts managed for different objectives, such as a wildlife preserve and a state hunting area.
buffering: Modification of environmental conditions by planting vegetation or changing topographic features. See also: reaction.
bulb: A short underground stem with fleshy scales or coats.
bulbate: Inflated.
bulbiferous: Bearing bulbs or bulblets.
bulbil (alt. bulbel, alt. bulblet): A small bulb or bulb-shaped body, especially one borne upon the stem, and usually produced for asexual reproduction.
bulbous: Having the character of a bulb.
bulk density: The mass or weight of oven dried soil at 100 to 110 degrees Centigrade, per unit of bulk volume, including air space.
bullate: Blistered or puckered.
bunch grass: A style of grass that grows in tufts.
bundle cluster: A cluster such as that of pine needles.
bundle scars: Tiny, somewhat circular dots within the leaf scar, caused by the breaking of the fibrovascular bundles which run through the petioles into the blades of the leaves.
bundle sheath: A clasping collar surrounding a collection of similar parts such as the collar on pine needles.
bur (alt. burr): A rough, prickly husk covering the fruit or seeds, such as the husk on a chestnut.
buried soil: One or more layers of soil, formerly at the surface, which have been covered by ash, sand, or other deposition.
burl: A deformed outgrowth on the trunk of a tree, often half a hemisphere in form, valued for the unusual wood grain; also the veneer made of such growths.
burn: 1. Scottish word for brook. 2. The controlled process of removing dangerous buildups of combustible materials and destroying weed seeds, etc.
burn scar: A scar on a tree trunk left when tissues were damaged by fire. It may later be covered by new tissue.
bursicle: A pouch-like receptacle.
bush: 1. A shrub, especially one that is low and thick with many stems rather than a single trunk. 2. A tree- or shrub-covered area in Australia or South Africa, or any uncleared land. 3. Sugar bush is a maple forestwhere sap is collected to make maple syrup or candy.
butte: A term from the western united States meaning an isolated hill with steep sides and a relatively flat top that is smaller than a mesa.
button center: A round center in a rose blossom, formed by unexpanded petaloids in very double roses.
buttress: 1. A flange of tissue protruding from the trunk of a tree, tapering outward at the base. 2. A projectingstructure of masonry or wood for supporting or giving stability to a wall or building.
c horizon: In soils, the partly weathered rock fragments which are the parent materials for the upper A horizonand B horizon. This is occasionally lacking. See also: D horizon.
caatinga: The area of northeastern Brazil covered with thorn scrub.
cabling: Connecting tree limbs with steel cable to alleviate ice storm damage.
cactiform: With succulent stems similar to Cactaceae.
cactoid: Resembling a cactus.
cactus (pl. cacti): A member of the family Cactaceae, having succulent stems and branches with scales or spines instead of leaves and found primarily in arid regions.
caducous: Falling off very early, usually applied to flower parts.
caingin clearing: A term used in southeast Asia for an area which has been cleared so that it can be used for farming.
cairn: Piled stones used as a landmark or memorial.
calcarate: Produced into or having a spur.
calcareous: Containing calcium or calcium carbonate (lime), as an alkaline soil.
calcareous ooze: Partially decomposed organic matter mixed with a quantity of calcareous material on the bottom of some bodies of water.
calcicole: A plant adapted to growing on limestone or alkaline soil.
calcification: A soil process where the surface soil is combined with calcium by the decomposition of plants, especially if a calcareous layer is formed. See also: podzolization.
calcifuge: A plant that does not grow well in lime or alkaline soil.
calcination: Decomposition due to the loss of bound water and carbon dioxide.
calcine: Like a calyx, or belonging to the calyx.
calciphile: A plant that must have lime or alkaline soil.
calciphobe: A plant preferring alkaline soils; an acidophilous plant.
caldera: A large crater formed by the collapse of the central part of a volcanic cone.
caliche: 1. A crumbly crust of calcium carbonate formed on a stony base in arid climates. 2. A term used in Chile and Peru for deposits of sodium nitrate.
calicole: A plant living on chalky or limy soils.
caliper: 1. An instrument used to measure the diameter of a tree, or other object. 2. The measurement thus attained, usually at breast height.
calli: Small outgrowths on the throat of the corolla of some plants, often acting as tactile guides for pollinators.
callosity: A hardened thickening.
callus (adj. callose): 1. A hard protuberance or callosity, sometimes resulting from a wound. 2. In the grasses, the tough often hairy swelling at the base or insertion of the lemma.
calmative: An herbal medicine that contains a mild sedative or has a calming effect.
Calvin cycle: The cycle of dark reactions of photosynthesis that occurs in the chloroplasts and involves the fixation of carbon dioxide and the formation of a six-carbon sugar.
calycine: Refers to a part of the calyx, or something that is like a calyx.
calycle (alt. calyculus): The epicalyx, a second calyx or involucre beneath the true calyx.
calyculate: Having bracts around the calyx or involucre imitating an outer calyx.
calyptra: A lid or hood. In mosses, the thin veil or hood covering the mouth of the capsule.
calyptrate: Having a calyptra.
calyx: The outer part (perianth) of the flower, usually green and formed of several divisions called sepals, that protects the bud.
calyx bract: A bract which takes the form of a petal or sepal.
calyx lobe: The portion of the sepal which is apical, or remains free, in a fused calyx.
calyx tube (alt. calyx-tube): A tube formed partly by the united bases of the sepals and partly by the receptacle. See also: hypanthium.
cambium: The internal layer of living cells between the inner bark and the sapwood where growth takes place that produces secondary xylem and phloem.
Cambrian: 1. The oldest geological period in the Paleozoic era, about 500 million years ago. 2. Refers to organisms formed during that period.
campanile: A bell tower, usually freestanding.
campanulate: Bell-shaped; cup-shaped with a broad base.
campestral: Growing in fields.
campo cerrado: A Brazilian type of parkland composed of scattered trees in dense grass.
campos: Grassland located south of the equator in Brazil.
camptodromous: A pattern of venation where the secondary veins curve toward the margin without forming loops.
campylotropous: Describes an ovule or seed so curved as to bring the apex and base nearly together.
canaliculate (syn. tubulose): Longitudinally channeled or grooved, especially on leaf stalks and midribs.
cancellate: A surface having the appearance of a lattice, with regularly arranged openings, e.g., the endostome of the Fontinalacae.
candle: The tender spring growth of the pine and some other needle-leaf evergreen species.
cane: A long, often supple, woody stem.
canescent: Hoary with gray pubescence.
canker: A patch of dead cells on a trunk or branches of a woody plant.
cano-tomentose: Density of hairs midway between canescent and tomentose.
canopy: The uppermost layer of branches and foliage of forest or a single tree.
canopy layer: The highest stratum of growth in a forest, where the trees form almost solid treetop canopies.
canopy trees: Forest trees which have reached a size where the crown becomes part of the uppermost layer.
cant hook: A term used in the united States for a tool used for rolling logs, consisting of a wooden lever with a moveable iron hook near the end, often with a lipped iron ring round the tip. See also: log lifter, peavey.
capability (alt. land capability): A measurement of the suitability of land for some particular use without permanent damage to the land.
capacity formula: Mathematical rule used in hydraulics to calculate the extent or discharge volume of a channel.
capillary: Hair-like.
capillary action (syn. capillarity): The phenomenon of a liquid spontaneously seeping up thin tubes due to adhesive and cohesive forcesand surface tension.
capillary porosity: The aggregate volume of small pores within a particular soil to retain water against the force of gravity.
capillary water: The part of soil water which is held cohesively as a continuous layer around particles and in spaces, most of it being available to plant roots.
capitate (syn. capitiform, alt. capitose): 1. Shaped like a head; collected into a head or dense cluster. 2. Terminated by a bulbous, swollen area.
capitellate: 1. Shaped like a tiny head. 2. Clustered in a compact headlike grouping.
capitulum: A dense inflorescence of unstalked flowers shaped like a globe, such as a buttonbush, Cephalanthus; or sometimes shaped flat, as in Compositae.
caprification: The commercial process of pollination of fig plants by wasps.
capsid bugs: Green or brown bugs that suck sap of young growth, causing distortion of flowers and leaves.
capsular: Belonging to or of the nature of a capsule.
capsule: 1. A dry dehiscent fruit composed of more than one carpel that splits partly open at maturity. 2. The enlarged distal end of the sporophyte; it contains the spores, and is sometimes known as the sporangium.
carapace: The hard case or shield covering part of the body of animals like turtles and some invertebrates.
carbohydrates: Neutral compounds of carbon, hydrogen and oxygen formed by green plants, including sugars, starches and cellulose.
carbon: Nonmetallic element found in all organic compounds.
carbon 14 dating: The selection and testing of undisturbed soils, buried materials such as wood, firepit remains, and other organic materials, for measurement of radioactive carbon 14 with a half-life of approximately 5,500 years, to determine the rough age of the selected materials.
carbon assimilation: Photosynthesis.
carbon cycle: The process of changing atmospheric carbon into sugar by photosynthesis in plants, synthesis of more complex organic compounds in higher plants and animals, and the return to carbon dioxide by respiration or death and decay of plant and animal tissues.
carbonate zone: A soil layer with concentrated carbonates, chiefly calcium carbonate, found most often in arid areas.
Carboniferous: Refers to the Pennsylvanian (upper carboniferous) and Mississippian (lower carboniferous) geological periods in the upper part of the Paleozoic era, about 200 to 260 million years ago.
carcinogen (adj. carcinogenic): Substance capable of producing or inciting cancer.
cardinal points: The four chief directions of a compass reading: north, south, east, and west.
cardioactive: Herbal medicines that can affect the heart.
carina: Keel.
carinal: On or relating to a ridge or keel.
carinate: Having a keel or projecting a longitudinal medial line on the lower surface.
carminatives: Herbal medicines that can dispel gas from the intestines, relieving colic.
carnivorous plant: A plant subsisting on nutrients obtained from the breakdown of animal tissue, usually that of insects.
carnose: Fleshy.
Carnoy's fluid: A liquid preservative for cytological materials, containing 3:1 absolute ethyl alcohol and glacial acetic acid.
carotene (alt. carotin): Orange-yellow hydrocarbon, a pigment which commonly appears in such plants as carrots and squash; a precursor of Vitamin A.
carpel: A simple pistil or one member of a compound pistil.
carpid: Half of a schizocarp, e.g., one of the winged seeds of a maple.
carpogonium: The female organ of red seaweeds.
carpophore: 1. The slender prolongation of the floral axis which in the Umbelliferae supports the pendulous ripe carpels. 2. The nonmotile spore of the carposporophyte.
carposporophyte: The post-sexual fruiting stage of a red seaweed.
carr: A fen.
carrying capacity: The maximum number of individuals of a particular species that a given area can maintain indefinitely.
cartilaginous: Hard and tough, but still flexible.
caruncle (syn. strophiole, adj. carunculate): An excrescence or appendage at or about the hilum of a seed.
caryophyllaceous: 1. Refers to members of Caryophyllaceae. 2. Refers to petals which have a long claw at the base.
caryopsis: A grain, such as grasses; a seed-like fruit with a thin pericarp adnate to the contained seed.
cassideous: Shaped like a helmet or hood.
castaneous: Of a chestnut-color; dark brown.
casual: A weed in a cultivated field which appears occasionally but does not naturalize.
casual species: Species which occur rarely in a community, such as a lilac, Syringa, but does not naturalize young plants in the area.
catabolism: Destructive metabolism releasing energy and breaking down complex materials in a living organism.
catadromous: When the first branch of a frond or vein in a pinnate leaf appears on the side facing towards the base.
cataphyll: A leaf, or leaf-like organ, usually found below ground.
catapult fruits: Those fruits that discharge their seeds forcefully; ballistic fruits.
catarobic: Refers to a wet or aquatic habitat where the slow breakdown of organic matter is occurring. Organic materials are given off into the medium with much of the oxygen used, but not enough to prohibit the occurrence of aerobic organisms.
caterpillars: The larvae of butterflies and moths, which often feed on leaves.
cathartics: Potent herbal laxatives.
cation: A positively charged ion.
catkin: A compact and often drooping cluster of reduced, stalkless, and usually unisexual flowers; an ament.
caudate: Having a slender tail-like appendage.
caudex: 1. The persistent, sometimes woody base of an otherwise herbaceous stem. 2. A trunk, especially that of a tree fern.
caudicle: The thread-like or strap-shaped stalk of a pollinium.
caulescent: Having a manifest stem above ground.
cauliflory (adj. cauliflorous): The state of flowering from the branches or trunk.
cauline: Belonging to the stem.
caustic (syn. corrosive): Capable of destroying by chemical action.
cell: One of the minute vesicles of protoplasm consisting typically of nucleus, cytoplasm, and, in the plant cell, photosynthetic pigments, all enclosed by a cell wall. Any structure containing a cavity, as the cells of an anther or ovary, etc.
cell membrane (syn. plasma membrane, syn. plasmalemma): A semipermeable limiting layer of cell protoplasm.
cell system pasturing: An attempt to replicate the method of natural grazing by bison. Livestock are placed in one section or cell of pasture with access to water until all vegetation is eaten or trampled to the ground, then moved to the next section. A common pattern features 10 cells with livestock moved monthly so each section is grazed in different months each year to encourage increase of ice cream grasses. See also: continuousgrazing, rotation grazing.
cellulose: The complex carbohydrate that is the principal component of cell walls of plants.
cement: A powder of lime and other minerals burned together in a kiln and finely pulverized which, when combined with water, hardens with hydration. It is used as the binding agent in mortar and concrete.
cenospecies: All the ecospecies that may exchange genes through hybridization, like the violets, Viola.
Cenozic: Refers to the geologic era extending from 40 million years ago to the present era, which started approximately a million years ago.
center of dispersal: The geographic area from which a taxon has spread or is spreading, such as where an alien plant was introduced.
center of diversity: A specific locality with high levels of genetic or species variance.
center of endemism: A unique geographic region with species which are known only to that area. See also: endemic.
center of origin: The geographic area in which a taxon originated and from which it is spread.
center pivot irrigation: A method of agricultural irrigation using a long, wheeled arm with many nozzles that pivots about the center of a circle; used primarily in arid regions.
central rays: The short immature ray florets comprising the central portion of the fully double flowers when at their prime stage (used in describing dahlias.)
central strand: The middle of many moss stems is made up of a bundle of much narrower and more slender cells, known as the "central strand".; This is usually continuous with the midrib or costa of the leaves, similar to the vascular bundles in the higher plants.
centrifugal: Progressing or developing outward from the center or axis.
centripetal: Progressing or developing inward from the outside and towards the center or axis.
centromere: The point or region on a chromosome to which the spindle attaches during mitosis and meiosis.
centrosome: Transparent cytoplasm adjacent to the cell nucleus.
centrum: The central portion; used specifically for the large central air space in hollow stems, such as those of Equistetum.
cephalanthium: The flower head of a Compositae species.
cephalium: A woolly growth at the top of the stem of some cacti, such as Melocactus, on which the flowers appear.
cephalodia: Tiny thalli growing in the upper cortex of some lichens.
cereal: Grain or plants that produce grain--mostly from the Graminae family--used as food.
ceriferous: Wax-producing; waxy.
cernuous: Drooping or nodding capsule, somewhat inclined as opposed to erect.
certified seed: Seeds that have been approved by a legally recognized certifying agency as being qualified under established standards of germination; they are free from disease and weeds and are true to variety.
cespitose (syn. caespitose): Growing in tufts; forming mats or tufts; often refers to a short plant with many stems or branches, forming a cushion appearance.
chafers: Beetles that attack plant roots as larvae and leaves as adults.
chaffy: Having or resembling chaff.
chain saw: 1. A power tool for cutting timber. 2. A tool with interlocking individual teeth that are chained together, with ropes on either end and powered by muscle.
chalaza: The area of an ovule, opposite the micropyle, to which the funicle is attached.
chalk: Soft gray, buff, or white limestone formed from the shells of foraminifers.
channeled: Deeply grooved longitudinally, like a gutter.
chaparral: A dry land, xerophytic, formation of impenetrable thickets, composed of stiff, thorny, small-leaved shrubs.
character: An attribute or property of an organism, functional or structural, which may be adapted through environmental conditions within genetically determined limits.
characteristic diversity: The pattern of distribution and abundance of habitats and their species populations under conditions where human influence on the ecosystem is no greater than that of any other biotic factor.
chart quadrat: A cart or map of a sample area showing the placement and area of each plant.
chartaceous: Having the texture of writing paper or parchment and usually not green.
chasmogamy (adj. chasmogamous): The opening of the perianth of a flower for the purpose of fertilization. See also: cleistogamy.
chasmophyte: A plant which grows in the crevices of rocks and rock faces. See also: chomophyte.
check dam: A short low dam constructed in a waterway to decrease the sp.ed of stream flow and to allow sediments to drop from the water.
chelate (n. chelator, n. chelation): The process whereby an organic chemical bonds with and removes free metal ions from solutions.
chemical stratification: A condition found in temperate lakes during the summer and winter stagnation periods in which certain horizontal layers become different chemically from adjacent ones, often causing turnover. See also: thermal stratification.
chemoautotrophic: Being autotrophic and oxidizing an inorganic compound as a source of energy, as a chemoautotrophic bacteria.
chemolithotrophic: Describes an organism which obtains its energy from the oxidation of inorganic compounds.
chemoorganotrophic: Describes a heterotroph which oxidizes chemical bonds for energy but requires organic carboncompounds to grow.
chemosynthesis: A process found in certain bacteria in which nutrition is assured by the ability to oxidize inorganicmaterials.
chemotaxis: Movement of an organism caused by a chemical stimulus.
chemotrophic: Refers to an organism that produces energy from a chemical reaction which does not depend on light. See also: heterotrophic, autotrophic, phototrophic.
chemotropism: Movement or growth of cells or organisms in response to chemical stimuli.
chemotype: A population of plants belonging to a particular species that differs chemically from others of that species.
chernozem (syn. black earth): A zonal group of soils with deep fertile surface soil, dark brown to black in color, rich in organic matter, grading into lighter colored soil below, and having a calcium carbonate layer at a depth of 1.5 to 4 feet (45 to 120 cm.). These are often found under tall grasslands in a temperate to cool, somewhat humidclimate.
chestnuts soils: A zonal group of soils with dark brown surface horizons grading into lighter colored soil below, and a calcium carbonate layer at depths of one to four feet (30 to 120 cm.). These are associated with grasslands in temperate to cool, subhumid to semiarid climates; moister than brown soils, drier than chernozem.
chianophile: A plant that can endure long snowy winters, or one that requires snow cover in winter.
chianophobe: A plant that does not tolerate long snowy winters, or one that can survive with little or no snow coverduring winter.
chiasma: A crosswise fusion, as occurs with chromosomes.
chicon: The blanched, compact shoots of chicory (Cichoricum intybus).
chilling requirements: Seeds which are dormant or doubly dormant may need actual outdoor climatic conditions of winter, or the indoor equivalent known as stratification. This is usually done by placing the seeds in moist soil in a plastic bag in the refrigerator for several weeks or months.
chimara (alt. chimera, alt. chimaera): A plant formed of the tissues of two different species mingled together and being intermediate in characteristics between the two parents.
chiseling: Working deeply into the subsoil with a chisel plow to break compaction. See also: subsoiling.
chitin: Horny material that forms exoskeletons of insects, arachnids, etc.
chlorenchyma tissue: Parenchyma cell containing chloroplasts found in plants.
chlorinity: The chloride content of a solution, often compared to seawater which is 19.3.
chlorophyll: The green coloring-matter within the cells of plants.
chlorophyllose: Containing chlorophyll.
chloroplast: The microscopic body within the cell which contains chlorophyll.
chlorosis (adj. chlorotic): A yellowing of the leaves, reflecting a deficiency of chlorophyll and caused by waterlogged soil or a lack of nutrients, often iron.
chlorotic: Refers to a plant that has chlorosis.
cholagogues: Herbal medicines which promote the flow of bile from the liver.
chomophyte: A plant that grows on rock fissures or crevices, on rocky ledges. See also: chasmophyte.
choripetalous: Refers to a corolla made up of separate petals. See also: polypetalous.
chorology: The study of regions or areas. See also: synchorology.
chresard: Water in soil that is available to plants for absorption.
chromatid: One of the usually paired and parallel strands of a duplicated chromosome joined by a singlecentromere.
chromatin: Material of the nucleus and chromosomes which can be stained deeply with certain dyes.
chromatophore: 1. In plants, a plastid which contains pigment in a cell such as a chromoplast or chloroplast. 2. In animals, a cell or group of cells with pigment having the capability of color change.
chromogen (adj. chromogenic): A pigment-producing microorganism.
chromoplast: A plastid other than a chloroplast, containing yellowish or red pigment.
chromosome: One of the set of bodies in the nucleus which determines the hereditary cell structure and function of a cell.
chrysalis: A pupa of a butterfly; broadly, any insect pupa.
Chrysophyta: A taxonomic division containing diatoms, golden-brown algae, and yellow-green algae, all single-celledand normally found in marine environments.
chubasco: A spinning disturbance near the Gulf of California, resembling dust whirls on land and waterspouts over water. These environmental disturbances reach great heights, becoming violent enough to capsize small craft.
chylocaulous: Refers to fleshy stems, like cactus.
chylophyllous: Refers to fleshy leaves, like agave.
ciliate: Marginally fringed with hairs (cilia).
cilium (pl. cilia): A short, usually stiff, usually unicellular, marginal hair; a hair-like thread of the endostome, alternating with the segments.
cincinnal: Refers to scorpoid cymes and other curled floral arrangements.
cincinnus: A monochasial cyme on which flowers appear in an order along a spiral.
cinereous: Ash-colored.
cinnamomeous: Cinnamon-colored.
circinate (alt. circinnate): 1. Curved into a circle so that the apex is nearly or quite bent around to the leaf base. 2. Coiled in a spiral, with the apex at the center. 3. Coiled from the top downward, as the young frond of a fern.
circle of vegetation: All of the species and communities that are restricted to a natural vegetation unit.
circulus: One of the concentric circles on a fish scale.
circumboreal: Said of plants which surround the Northern Hemispere, appearing in both the Old and New Worlds, such as the dandelion.
circumpolar: Refers to species that occur all around the poles in either the north or south and in both the eastern and western hemispheres.
circumposition: A propagative method also known as air layering.
cirque: A deeply-eroded area with steep slopes in a region of past glaciers.
cirrate (syn. cirrhate): Applied to leaves which curl up in drying. Cirrate leaves are more regularly curled than crispate leaves.
cirrhose: Having a wavy hair point.
cistern: An artificial reservoir for collecting and storing rainwater, as the type used for irrigation, which is often ornamental in design and frequently serves only as a decorative function.
citation: In botanical systematics, a quotation from a book or author referencing an authority or precedent.
CITES (alt. C.I.T.E.S.): The Convention on International Trade of Endangered species, which provides regulations for the international trade in listed species of plants and animals.
citronella: A fragrant oil used in perfumery and as an insect repellent derived from the grass Cymbopogon nardus.
citrus: Members of the family Rutaceae, e.g., oranges and limes, etc., grown in warm areas as edible fruits.
cladocarporus: Having the sporophyte terminating a short special fertile branch; somewhat like half-way between acrocarpous and pleurocarpous.
cladophyll (alt. cladode): A flattened, leaf-like photosynthetic stem or branch not itself leaf-bearing.
clambering: Describes a plant that sprawls or climbs but lacks tendrils.
clasping: A leaf whose base wholly or partly surrounds the stem.
classification: Systematic arrangement of hierarchal levels of taxonomy.
clathrate: Lattice-like; having thick lateral (adjacent) cell walls and thin surficial walls.
clavate: Club-shaped; gradually thickening from a slender base.
clay soil (syn. clay loam): A soil, usually heavy and poorly drained, containing a preponderance of very fine particles.
clean cultivation: Hoeing out weeds and keeping the surface of the soil loose to lessen weed seed germination.
clearcut (alt. clear felling): The cutting of all trees in a forest.
cleft: Divided nearly to the midvein.
cleistocarpous: Capsule opening irregularly, not by a lid or valves.
cleistogamy (adj. cleistogamous): The condition of having flowers which self-pollinate in the bud, without the opening of the flower. See also: chasmogamy.
climax stage (alt. climax community): The ultimate stage in the process of succession, occurring when a plant's ecosystem has reached a point of stability.
climber: A plant that can climb given support.
clinandrium: In Orchidaceae, the part of the central column which holds the anthers.
cline (adj. clinal): A gradual morphological or physiological change in a group of related organisms across their range, usually correlated to environmental or geographic transition.
clinker: The material that emerges from the cement kiln after burning. It is in the form of dark, porous nodules which are ground with a small amount of gypsum to produce cement.
cloche: Covers for individual plants, protecting against frost, birds and pests; a miniature cold frame.
clod: A lump of soil.
clone: A group of plants all originating by vegetative propagation from a single plant, and therefore genetically identical to it and to one another.
cloud forest: A mountain forest covered by a persistent mist that creates stunted trees and abundant epiphytes.
club root: A fungus that causes knobby roots in stocks, wallflowers, and other members of the cabbage family.
clump-forming: Describes a plant which reproduces vegetatively, forming smaller crowns around the parent which can be divided and planted in new locations.
cluster: A group of two or more occurring close together.
clypeate: Halberd or shield-shaped.
co-management: The sharing of authority, responsibility, and benefits among government, businesses, and local communities in the management of natural resources, e.g., cooperation among the National wildflowerResearch Center, Texas Department of Agriculture, landscape architects, and nurseries in the production of native plants for landscaping.
coalesce: To fuse together.
coalescence: The union of parts or organs of the same kind.
coarse-toothed: With large teeth; dentate, serrate.
cob: The rachis of the female corn spike, fruit of Zea mays.
cobblestone: A naturally rounded stone larger than a pebble and smaller than a boulder; especially such a stone used in paving a street or in construction.
coccus (pl. cocci): A lobe of a schizocarp containing a single seed.
cochlear: Describes a coiled arrangement of the corolla lobes in a bud, a type of imbricate aestivation.
cochleariform: Rounded and concave like a spoon or ladle.
cochleate: Spiral, like a snail's shell.
cocous (pl. Cocci): One of the parts into which a lobed fruit with 1-seeded cells splits.
Codes of Nomenclature: The general rules for the assignment of scientific names to taxa.
codominant leaders: When two main branches of a tree are of equal strength and size, leading to the possible danger of the tree splitting.
coefficient of association: A mathematical statement of the frequency of occurrence together of two species not due merely to chance, calculated by dividing the number of samples in which both occur by the number of samples in which it would be expected they both would occur.
coensorus: In ferns, the extension of a sorus, or united sori that appear to be a single sorus.
coetaneous: Of the same age or existing at the same time.
coexist (n. coexistence): To live together in the same place and at the same time.
coherent: Refers to parts that are usually separate but have become fused together, such as petals in a floral tube.
cohesion: The union of one organ with another of like nature.
coir: A stiff coarse fiber from the outer husk of a coconut.
cold frame: A frame covered in glass or plastic and without artificial heat used to protect plants and seedlingsoutdoors.
cold room: An area to keep plant specimens fresh until they can be pressed.
coleoptile (alt. coleophyll): The first leaf following the cotyledon of a monocotyledon which forms a protective sheath around the plumule.
coleorhiza: Protective sheath around the radicle in a grass embryo.
collateral: Situated side by side.
collecting permits: Papers granting permission to collect specimens of flora of parks, nature preserves, foreign countries, or other protected areas.
collection bottles: Glass or plastic bottles with waterproof screw tops or vial type bottles, used to collect specimens such as pollen, buds, bark, seeds, insects, etc.
collenchyma: A type of supportive tissue consisting of elongated cells with thickened walls and containing chloroplasts.
colleter: A group or tuft of mucilaginous secretory hairs, often found near the base of the leaf lamina and on the calyx in memebers of the Apocynaceae and Asclepiadaceae families.
colliculate: Having small hill-like eminences.
colloidal clay: Extremely fine, microscopic particles of rock.
colloidal dispersion: A mixture containing particles larger than those found in a solution but small enough to remain suspended for a very long time. See also: colloidal suspension.
colloidal suspension: Minute particles remaining intermixed in a liquid without being dissolved. See also: Brownian movement, colloidal dispersion.
collum: The neck or tapering base of the capsule.
colonial: Forming colonies by means of underground rhizomes, stolons, etc.
colony: A group of lichen thalli growing together.
color charts: Hue chips used to simulate colors in the field, as flowers may lose or change color(s) when dried. Examples of such charts are the horticulture Society Color Chart, Nickerson Color Fan, and Horticultural Color Chart.
colporate: Describes a pollen grain which has both an elongated and a rounded aperture.
colpus (pl. colpi, adj. colpate): An elongated aperture of a pollen grain with a length/breadth ratio greater than 2. See also: colporate, porate.
columella: In mosses, the central axis of the capsule; around it and between it and the outer wall of the capsule are borne the spores. Sometimes the lid adheres to it and is raised upon it.
column: In orchids, a structure formed by the union of stamens, style, and stigma.
column foot: In Orchidaceae, the basal platform to which the lip is attached to the column.
coma: Comal tuft, a tuft of leaves at the tip of a stem or branch.
combination: In taxonomy, the name below the rank of genus, which combines the genus name along with the speciesand lower ranks, such as subspecies, variety, etc.
commensalism: A type of symbiosis where there are two organisms from different species. One obtains food or other benefits from the other without damaging or benefiting it.
commercial synonym: 1. An alternative choice of a legitimate name for a cultivar. 2. A shortened form of the original name, used where the original name is not conducive to sales, e.g., Ilex vomitoria. 3. A sales name chosen by the originator of the cultivar or with the originator's approval.
commissure: The surface by which one carpel joins another, as in the Umbelliferae.
common name: Identifying term which often reflects appearance, legend, or use of a plant species. It may var. greatly by region, increasing the need for standard binomial nomenclature.
common property resource management: The supervision of a specific resource (such as a forest or pasture) by a well-defined group of users with the authority to regulate its use by members and outsiders.
comose: Furnished with or resembling a tuft of hairs.
compact: Pressed together or closely joined; in rhizomes, those with short internodes and closely spaced stipes.
companion plants: 1. Plants which work well together aesthetically, perhaps because they have complementary coloring, or flower at different times of the year, etc. 2. Two or more plants that are used together because one or more are beneficial to one or more of the others, for instance by repelling pests that prey on the other(s).
comparative advantage: Relative supremacy with which a region or state may produce a good or service.
complete fertilizer: A compound containing the three essential minerals for growth: nitrogen (N), phosphorous (P), potassium (K).
complete flower: Having all the principal parts, particularly the stamens and pistils.
complex: A group of very similar and obviously related plants where it is difficult to find identification limitations, and where the relationships are not fully understood.
complicate: Folded upon itself; folded lengthwise.
composite: Member of the family Compositae, having compound flower heads, e.g., the daisy, the aster, the sunflower, etc. See also: compound flower head.
composite cultivar: A group composed of several closely related cultivars; grex.
compost: Decomposed organic maker, usually used to enrich the soil.
compound: Composed of two or more similar parts united into one whole. Compound leaf: one divided into separate leaflets.
compound flower head (alt. composite flower head): A flower head with outer ray flowers forming petals surrounding the inner disc flowers, as in the Compositae.
compound leaf: A leaf divided into smaller leaflets.
compressed: Flattened, especially laterally.
concatenate: Linked, as on a chain.
concave: Depressed or hollowed out.
concavo-convex: Bulging out on one side and caving in on the other, like an eggshell or lens.
concentric: Having a common center, as the rings on a target.
conceptacle: A flask-like structure containing reproductive organs.
conceptual design: Rough drawing showing the general shape and location of all design elements such as buildings, fences, slopes, plantings, etc. in a landscape plan.
concolorous: Uniform in color.
concressant: Growing together, especially of parts that were originally separate.
concrete: A hard compact building material formed when a mixture of cement, water, sand, gravel, and perhaps other aggregates, undergoes hydration.
concretion: Mineral mass formed within another type of rock, often very different in appearance and composition.
conduplicate: Folded together lengthwise.
cone: A conical fruit consisting of seed-bearing, overlapping scales surrounding a central axis.
cone-scale: One of the scales of a cone.
conferted: Closely crowded. See also: congested, constipate.
confervoid: Formed of fine threads, as green algae.
conflorescence: A compound inflorescence consisting of two or more simple inflorescences.
confluent: Running into each other; blended into one.
conform: Similar in shape and size to others.
confused center: A flower center whose petals are disorganized, not forming a pattern.
congeneric: Belonging to the same genus.
congested: Close together. See also: conferted, constipate.
congregate: Growing in dense proximity.
conical: Cone-shaped; widest at the base and tapering to the apex.
conical root: A taproot.
conifer: A cone-bearing tree of the pine family, usually evergreen.
coniferous: Cone-bearing.
conjugation: The union of gametes.
connate: United; used especially of like structures joined from the start.
connate-perfoliate: Where opposite leaves are completely joined at the bases, leaving the appearance that the stem pierces through.
connective: The portion of a stamen which connects the two cells of the anther.
connivent: Coming into contact; converging, but not fused.
conoidal: Nearly conical.
conservation lists: Recommended protection lists of endangered, threatened, and protected plants, giving information from groups other than those with enforcement powers.
conservatory: A structure or room made primarily of glass and used for the cultivation of tender and exotic plants. A formal term for a greenhouse.
conspecific: Belonging to the same genus.
conspicuous: Easily visible without a lens, often extended to mean showy or prominent.
constricted: Used of capsules that become narrowed under the opening when dry.
construction documents: Final drawings with accompanying written specifications to be used by contractors in completing a landscape project.
consumers: Organisms which break down organic material (such as sugars and proteins) to obtain energy for their own growth, and then return inorganic components to the environment, where they are again available.
container gardening: Cultivation of flowers and vegetables in boxes, urns, garbage bags, etc., where direct soil planting is not feasible, as on apartment balconies, in penthouses and desert areas, etc.
container-grown: Grown from a seedling in the container it is to be sold in.
contiguous: In immediate contact.
continental: Describes a climate little influenced by sea, with large ranges between summer and winter temperatures.
continuous: Not interrupted.
contorted: Irregularly twisted or distorted.
contracted: Reduced in size by or as if by squeezing or forcing together.
contractile roots: Roots that can shorten themselves much like a worm does, drawing the plant down deeper into the soil. They usually have a wrinkled surface for expanding and contracting.
controlled burn: A fire started to rid an area of flammable materials in order to prevent a more dangerous or costly wildfire.
convariety (alt. convar): A group of similar cultivars within a variable species or hybrids between two species; the term has now been replaced in most cases by the word "group".
convergent: Coming in contact, but not fused.
convex: Arched outward.
convolute: Rolled up longitudinally.
coppice: 1. A thicket or copse of small trees. 2. To cut a plant almost to the ground each year so as to produce more vigorous growth.
copse: A thicket of small trees or shrubs.
coralloid: Shaped like coral, with many branches.
cordate (alt. chordate): Heart-shaped with the point away from the stem.
cordiform: Heart-shaped in all three dimensions.
cordon: A woody plant, most often a fruit tree, trained to grow as a single stem on a support.
coriaceous: Leathery in texture.
corm: The enlarged fleshy base of a stem, bulb-like but solid.
cormel (alt. cormlet): A small corm that develops at the base of the mother corm.
cormophyte: A land plant belonging to the former botanical division Cormophyta, having a stem and root system.
cormous: Bearing corms.
corn fork: A fork shaped like a scoop shovel, but with tines instead of a blade.
corneous: Having a horny texture.
cornicle: Wax-secreting tubes of certain insects, such as aphids.
corniculate: Having horn-like projections.
cornucopia: Curved horn overflowing with edible produce, symbolizing abundance.
cornucopiate: Shaped like a cornucopia or horn.
cornute: Spurred or horned.
corolla: The petals of a flower; the inner perianth of distinct or connate petals.
corolline corona: Fleshy ridges or outgrowths of tissue attached to the corolla tube.
corona: A crown of appendages between the corolla and stamens, or on the corolla or stamens. See also: crown.
coroniform: Shaped like a crown.
corpusculum: The central part of a pollinarium, characteristic of the families Orchidaceae and Asclepiadaceae.
corrugate: Wrinkled or in folds.
cortex: 1. In rhizomes and other axes, the tissue between the stele and the epidermis. 2. In lichens, the outermost layer of the thallus. 3. In seaweeds and fungi, the tissue external to the central tissue of longitudinal cells.
corticate: Having a cortex.
corticolous: Growing on the woody parts of trees and shrubs.
corymb: A flat-topped or convex open flower cluster, the outer flowers opening first. In the stricter use of the word, equivalent to a contracted raceme and progressing in its flowering from the margin inward.
corymbose: In corymbs, or corymb-like.
cosmopolitan: Widely distributed over the world.
costa: A rib; a midrib or mid-nerve of a pinna or moss leaf.
costapalmate: Ribbed or veined palmately.
costate: Having a costa. Ribbed; having one or more longitudinal ribs or nerves.
costule: An axis that is a branch of a costa or another costule.
cottage garden: A usually small, informal garden making optimal use of space.
cotyledon (syn. seed leaf): One of the first leaves to appear after germination (there may be one, two, or more); the foliar portion of the embryo as found in the seed. See also: true leaf.
cotype: An additional type herbarium specimen from which the taxon is described.
counteradaptation: Reciprocal acclimation of two or more species to each other over a period of time.
counterirritant: Herbal preparations that produce irritation when applied locally to stimulate circulation in the area of another irritated area.
cove: A small bay, especially on inland lakes.
crateriform: In the shape of a saucer or shallow cup; hemispherical or more shallow.
creeper: A plant running along at or near the surface of the ground and rooting. See also: creeping.
cremocarp: A dry fruit consisting of two one-seeded carpels that separate into mericarps upon ripening; schizocarp.
crenate: Dentate with the teeth much rounded.
crenulate: Finely crenate.
crescentic: Shaped like a crescent moon.
crest: A fan-like appendage, as can be found on some fern fronds; in spores, a tall, irregular ridge.
cretaceous: Chalky.
cribose: Peristome teeth perforated with small apertures.
crinite: Bearded with long weak hairs.
crinoid: Like a lily.
crispate (syn. crisped): Frizzled, curled, and twisted in various ways.
crisped: Curly-edged, as seen on some fern fronds.
crispy-hairy: With ringlets.
cristate: Bearing an elevated appendage resembling a crest.
crop rotation: Process whereby a different crop is planted in a field each successive year, preferably the following crop utilizing nutrients not greatly used by the preceding crop. Insect and disease vectors are also controlled by rotation.
crosier (alt. crozier): The unopened coiled leaves of some ferns, especially on the dormant crown.
cross-fertilization: Fertilization by the joining of gametes from different individuals of the same species (cross-pollination), or from different species (hybridization).
cross-pollination: The transfer of pollen from the anther of the flower of one plant to the flowers of a different plant.
crotch: The angle formed between two joining branches.
crown: 1. The site on a plant where roots join the stem. 2. In trees, the branches, twigs, and leaves that form the top of a tree. 3. The corona. 4. In roses, the region of the bud union; the point near soil level where the top variety and the understock are joined. 5. An inner appendage to a petal or to the throat of a corolla.
crown gall: Galls on shoots or roots of shrubs, especially those of the rose family, caused by soil bacteria.
crownshaft: An apparent extension of the bole in some Palmae, formed by overlapping and sheathing bases of the leaves.
cruciate: Cross-shaped.
crucifer (adj. cruciferous): Any plant of the family Cruciferae, including the cabbage, radish, turnip, and mustard.
crumpled: Corrugate; wrinkled.
crushed granite: Pea-sized chips of granite used for paving.
crustaceous: Of hard and brittle texture.
crustose: A form of lichen lacking a lower cortex and rhizines and having thalli that grow in contact with the substratum.
cryogenics: 1. The branch of physics dealing with the effects and production of very low temperatures, as applied to living organisms. 2. Dormant preservation by freezing, drying, or both.
cryptogam: A general name for plants, and plant-like organisms that lack flowers and are not reproduced by seeds, e.g., including ferns, mosses, fungi, and algae. The name is close in translation to something like "hidden marriage."
cryptopore: A stoma which is immersed.
crystalline: Looking like crystals or having the nature of crystals.
cube (adj. cubical): A solid with six equal square sides.
cubiform: Shaped like dice.
cucullate: Hooded or hood-shaped; cowled.
cucullate calyptra: In mosses, a calyptra that is hood-shaped and split on one side only.
cucullus: A hood-like tissue on some seeds.
cucumiform: Shaped like a cucumber.
cucurbit: Any of the various twining or climbing plants of the family Cucurbitaceae, including the melon, gourd, squash, etc.
culm: The peculiar aerial stem which bears flowers, found in grasses, sedges, and rushes.
cultigen: A plant developed in horticulture and found only under cultivation or as an escape.
cultispec: A cultigen that should be given species recognition.
cultivar: An unvarying variety of plant produced by selective hybridization, or, sometimes found in wild populations, and maintained by vegetative propagation or by inbred seed.
cultivar class: A taxon consisting of a group of cultivars.
cultivate: To work the soil in order to break it up and remove weeds.
cultivation: 1. A term for the tilling of soil. 2. Working up the bare soil around plants to kill weeds and allow air and water to penetrate to plant roots.
cultivator: A tool which may range in size from a hand-pushed garden implement to sets of teeth attached to a tractor, for the purpose of digging weeds and rounding soil over the base of plants.
culton: A recognizable plant originating in or maintained by cultivation, reflecting that not all such entities must remain cultivars.
cultriform: Curved like a short, wide scimitar.
cuneate: Wedge-shaped; triangular with the acute angle downward.
cup: The cup-like involucre surrounding an acorn. See also: crateriform.
cupped form: Having an open center, with the stamens visible.
cupreous: With coppery appearance.
cupressoid: With foliage like cypress; Cupressus.
cupule: A cup-shaped anatomical structure, like that holding an acorn, which is made of hardened, joined bracts. See also: crateriform.
cupuliform: Cup-shaped.
cure: The hardening of concrete, often controlled by keeping it moist.
curvate: Flexing or bending from a straight line.
curvinerved: Having curved parallel veins, as the leaf of a dogwood.
cusp: A short, abrupt, rigid point. See also: cuspidate.
cuspidate: Tipped with a cusp or sharp and rigid point. See also: cusp.
cut flower garden: An area set aside for the growing of plants which are to be used for the production of flowers for arrangement inside the house.
cut flowers (alt. cutting flowers): Species of flowers which are removed from the plant for arrangements and which easily retain their freshness.
cuticle: Skin or epidermis. The waterproof layer of the epidermis of plants.
cutin: A thin waxy covering on the outer layer of a leaf.
cutting: What growers of houseplants call slips, used for propagating new plants. The method involves cutting or breaking off a part of the plant, inserting it in growing medium so it can grow a new plant like the one from which it came. Hardwood cuttings are mature wood; softwood cuttings are taken in spring or early summer from tips when plants are actively growing; semihardwood cuttings are taken in late summer or fall when growth has slowed and wood is beginning to harden.
cutting garden: A garden of flowers which can be cut and used in arrangements.
cutwater: A V-shaped projection at the base of a pier or bridge support used to deflect the force of water in a river or stream.
cutworms: Soil-living brownish caterpillars that feed at night, often severing stems of herbaceous plants.
Cyanophyta: A taxonomic division containing cyanophytes, cyanobacteria, and blue-green algae. These may be singlecells or colonies, and reproduce by fission. They are found in many environments: damp soil and rocks, fresh water, and salt water.
cyathiform: Cup-shaped.
cyathium (pl. cyathia, adj. cyathiform, adj. cyathophorous): Cup-shaped. An inflorescence with unisexual flowers surrounded by a cup-like cluster of involucralbracts, e.g., a poinsettia.
cycad: Any plant of the order Cycadales, consisting of palm-like, cone-bearing, evergreen tropical plants that reproduce by means of spermatozoids and have large pinnately compound, usually fan-shaped leaves.
cyclone (adj. cyclonic): 1. A hurricane or typhoon; winds blowing counterclockwise in the northern hemisphere and clockwise in the southern hemisphere, at sp.s of 90 to 130 miles per hour (150 to 217 km/hr) around a calm center, with a forward thrust of 20-30 mph (33-50 km/hr) and a width of 50 to 900 miles (83-1500 km) diameter. 2. Popularly, any storm moving in a circular motion like a tornado.
cygneous: Curved suddenly downward, like a swan's neck.
cylindraceous (alt. cylindric, alt. cylindroid): Rod-shaped.
cylindrical: Having the shape of a cylinder.
cymbiform: Boat-shaped.
cyme: A usually broad and flattish determinate inflorescence, i.e., with its central or terminal flowersblooming earliest.
cymose: Bearing cymes, or cyme-like.
cymule: A small cyme, usually sparsely flowered.
cystocarp: A carposporophyte contained in a wall of sterile filaments.
cystolith: A concretion within a cell cavity consisting of calcium carbonate and occurring in plants such as figs.
cytokinin: Any of various plant growth hormones, such as kinetin, that grow and promote cell division and delay the senescence of leaves.
cytology (adj. cytological): The study of cells.
cytoplasm: The part of the protoplasm that is not the nucleus.
cytoskeleton: The network of protein filaments and microtubules in the cytoplasm that controls cell shape, maintains intracellular organization and, in some organisms, is involved in cell movement.
D horizon: The soil layer below the effect of weathering, made up of undifferentiated and unconsolidated parent materials, located immediately below the c horizon. See also: A horizon, B horizon.
dactyloid (alt. dactylose): Finger-like.
dale: A vale or valley.
damping off (alt. dampen off): Collapse of small seedlings due to fungi attacking stem at soil level.
dark reaction: Those chemical reactions in photosynthesis not requiring the presence of light and involving the reduction of carbon dioxide to form sugar. See also: Calvin cycle.
data retrieval: The process--manual or automated--of identifying and locating specific facts in stored documents, published or unpublished, and specimen collections of interest to particular uses. See also: literature retrieval, document retrieval.
day degrees: The mathematical statement of the sum of degrees above a threshold for a designated period, such as those above freezing for the growing season. See also: temperature summation.
day-neutral plant: A plant that blooms when the length of day is either long or short. See also: photoperiodism.
dbh: An abbreviation for the phrase "diameter at breast height", a measurement of the thickness of a treetrunk about four feet from the ground.
deadhead: To remove the blooms after flowering to encourage the development of new flowers.
dealkalization: Removal of base ions from soil by leaching or by chemical treatment with exchangeable sodium. See also: alkali soil.
decaploid: Having ten sets of chromosomes.
decapod: Animals like lobsters and crabs from the order Decapoda, class Crustacea.
decidulignosa: Communities of deciduous trees and shrubs.
deciduous: 1. Not persistent. 2. A tree losing its leaves at the end of the growing season; nonevergreen.
declinate: Bending downwards.
decomposer: Any of various organisms, usually a bacterium or fungus, that breaks down organic substances making the nutrients available again.
decomposition: The breakdown of tissues and compounds into simpler substances which act as soil nutrients.
decompound: More than once compound or divided.
decordicate: Lacking a cortex.
decreaser: A species that gradually disappears under continued grazing. See also: increaser, population density, cover.
decrescent: Becoming gradually less.
decumbent: Reclining, but with the tip ascending.
decurrent: Describes a leaf that extends down the stem below the insertion.
decurved: With a downward curve.
decussate: Alternating in pairs at right angles.
deep watering: Inundating an area with water for a long period of time, perhaps 24 hours or more, to permeate the deepest layers of subsoil, thereby pulling roots down where they will not easily perish from drought.
deferred grazing: The delay of grazing in forage after growth has started, until development has reached a stage that will promote additional vigor of the plants. See also: cell system pasturing, continuous grazing, rotation grazing.
deficiency disease: A stress condition or disease of an organism caused by lack of a nutritive substance such as a vitamin or mineral.
definite: Of a constant number, not exceeding 20.
deflected: Bent downward at a sharp angle.
deflexed: Bent or turned abruptly downward.
deflocculation: Soil aggregates containing clay separating into individual particles.
deflorate: Flowering has completed for the season.
defoliant: A chemical substance which causes a plant to drop its leaves.
defoliate (n. defoliation): 1. To cause the leaves of a plant to drop. 2. To remove the leaves of a plant.
deforestation: Clearing trees from a woodland, often done to promote food for wildlife as well as to provide timber.
deformed: Misshapend, distorted.
degradation: Loss of friability or fertility of soil resulting from leaching.
dehisce: To split apart and discharge seeds or spores.
dehiscence (adj. dehiscent): 1. Breaking open at maturity to discharge seeds or spores. 2. Opening regularly to let seeds or spores escape by valves, slits, etc., as a capsule or anther. See also: indehiscent.
dehorning: Severely pruning shrubs or trees, often carried to extremes of butchery.
delicate: Fragile; easily broken.
deliquesce (n. deliquescence, adj. deliquescent): 1. To branch into many subdivisions and lacking a main axis. 2. To liquefy or become soft with age, as occurs with some fungi.
deltate: Broadly triangular with an obtuse apex.
deltoid (alt. deltate): A low triangle attached at the middle of the wide part, rather than at the point; shaped like the Greek letter delta.
demarcation: An outline, boundary, delimitation, separation.
deme: One or more populations of a taxon; a population that will interbreed.
demersed: Constantly under water.
demography: The study of populations and their analysis regarding reproduction, deaths, age, etc.
demulcents: Herbal medicines that can break up phlegm or other mucus; sometimes used externally to sooth and soften skin.
dendroid (alt. dendritic): 1. Shaped like a tree. 2. Arranged in a shape like a tree, like some hairs on Cruciferae.
dendrology: The study of woody plants.
denitrification: The loss or removal of nitrogen or nitrogen compounds; specifically, a reduction of nitrates or nitrites caused by bacteria that usually results in the escape of nitrogen into the air.
density-dependent factor: An influence that hinges on a certain density of individuals to be fully effective, like peach trees or Amygdalis that must be 75 feet or closer for insects to successfully cross pollinate them.
density-independent factor: An influence that is effective regardless of density of a population, like the influence of a drought. Some scientists dispute the existence of such a factor. See also: nonreactive factor.
dentate: Toothed, usually with the teeth directed outward.
dentation: The teeth along the margin of an organ.
denticle: A small tooth; in plants of the family Rubiaceae, thick papillate tubercles along the margin of the interpetiolar stipules.
denticulate: Minutely dentate.
dentiform: Tooth-shaped.
deoperculate: Applies to a capsule after its lid has detached.
deoxyribonucleic acid (abr. DNA): The chief material constituting genes and chromosomes.
depauperate: Starved; prevented from coming to its natural size through lack of nourishment.
dependence: An association between organisms in which the dependent one receives benefits but gives no benefit to the other, characteristic of such plants as mistletoe, Phoradendron, living on an oak, Quercus; not reciprocal. See also: symbiosis, competition, coaction, parasite.
dependency zone (alt. dependency range): A belt surrounding an area of private land which supplements the use of the private land with additional use of public land.
dependent property (alt. dependent range): Privately controlled land or water assumed to have special claim for use of public or cooperatively controlled range.
deplanate: Flat.
depressed: Somewhat flattened from above.
desalinization: 1. The process of removal of salt from sea water to make drinking water. 2. Removal of salts from soil, usually by leaching.
descending: Bending gradually downward.
description: A list of characters which gives the attributes or features of a specific taxon.
desert grassland: Areas of the southwestern united States characterized by several species of adapted deep-rootedgrasses such as grama grass, three awn grass, and curly mesquite.
desert pavement: The stony surface of dryland areas when fine materials have disappeared from actions of water and wind.
deserta: Various types of plants found in areas that are low in available water like arid deserts, saline deserts, permafrost deserts, tundra, strand vegetation, and rocky mountainsides.
desiccate (n. dessication): To dry up.
desilting area (alt. desilting basin, settling basin): An expanse set aside above a dam, pond or field solely for the deposit of silt and debris from flowing water. See also: detention basin.
detention basin (alt. detention dam, detention area, detention pond): A man-made holding area for the purpose of storing sewer overflow and surface runoff until such time as the water may be released for treatment without causing flooding.
determinate: Having growth where a bud or flower terminates the growing tip, e.g., a determinate inflorescence.
dethatcher (alt. de-thatcher): A tool which combs clippings and thatch to the surface of the lawn.
detritivores: Organisms such as fungi, bacteria, and earthworms which consume nonliving material.
detritus: 1. Any loose material that has separated from a mass, such as gravel from a rock face.
Devonian: A geological period in the Paleozoic era, which lasted from about 325 million years to 45 million years ago.
dew point: The temperature at which air is capable of holding no additional water vapor, with either a drop in temperature or an increase in water vapor causing the vapor to condense into liquid as rain, fog, or dew. During the course of precipitation, the relative humidity is 100 percent and the saturation deficit is zero.
dextrorse: Turned to the right.
diagonal: The average, a compromise of position.
dialypetalous: With separate petals.
dialysis: Separation of dissolved substances by their unequal diffusion through semipermeable membranes.
diameter at breast height (alt,. diameter breast high, abr. d.b.h., abr. DBH): The width of the trunk of a standing tree, measured at 4.5 feet (1.3 meters) above ground surface.
diandrous: With two perfect stamens.
diaphanous: Very thin and transparent or translucent.
diaphoretics: Herbal medicines that promote perspiration and lower temperature.
diaphragm: Dividing membrane or partition.
diaspore: A reproductive portion of a plant like a seed or bud, that is dispersed and may give rise to a new plant. See also: disseminule.
diastrophism: Displacement of the earth�s crust by folding or slippage, causing the formation of mountains, chasms, etc.
diatom: Any of the minute planktonic unicellular or colonial algae of the class Bacillariophyceae, which contain silica.
diatomaceous ooze: Material consisting of siliceous remains of diatoms, found in cold seas.
dibble (alt. dibber): A small hand implement used to make holes in the ground for plants, seeds and, most often, bulbs.
dibrachiate: Refers to branches that spread widely.
dicarpellary: Composed of two carpels.
dichasium: A cyme with opposite branching below the terminating flower.
dichlamydeous: Describes a flower which has two whorls of perianth parts.
dichloro-diphenyl-trichlorethane (abr. DDT): An insecticide extensively used during the period after World War II that is now outlawed in the unitedStates and most of the industrialized world.
dichogamy: The differing times of maturation of stamens and pistils in a flower.
dichotomous: Forking regularly by pairs.
dichotomous key (syn. floral key): A series of choices leading to the identification of a species.
dichotomy: The division of a growing point into two halves.
diclinous (alt. diclinic): Having the stamens and the pistils in separate flowers.
dicotyledon (adj. dicotyledonous): A flowering plant with two cotyledons.
dicoumarol: A compound derived from spoiled sweet clover hay and used to delay clotting of blood.
didymous: Twin; found in pairs.
didynamous: Refers to stamens found in two pairs of unequal length.
dieback: The dying of the outer portions of a plant due to disease or weather damage; death of part or all of the woody portion of a plant.
diel: The 24-hour period of night and day. See also: diurnal, nocturnal, crepuscular.
differential species (alt. differentiating species): A species with high fidelity to a particular community that can be used to distinguish vegetation units.
differentiation: 1. Maturation of a cell, organ, or immature organism from juvenile to adult status. 2. The development of new kinds of organisms in the course of evolution.
difform: Not similar.
dig in: To bury during the process of turning soil for planting, as occurs with compost, fertilizer, etc.
digamous: With both sexes in the same flower cluster.
digestion: The conversion of complex organic substances into simpler fats, proteins, and carbohydrates by chemical reactions and enzymatic processes.
digitalin: One of the mixtures of glycosides used in making digitalis.
digitalis: A drug derived from the seed and dried powdered leaves of plants of the genus Digitalis containing important glycosides and serving as a powerful cardiac stimulant and a diuretic.
digitate: Finger-like; compound, with the members arising together at the apex of the support.
digonous: Two-angled, as are the stems of some cacti.
digynous: With two separated carpels or styles.
dihybrid: A crossbreed; an organism that came about from the breeding of parents that differ in at least two characters, e.g., leaf shape and plant height.
dike: An embankment built to protect land from flooding or erosion, or to stop the loss of water from wetlands.
dilettante: A rather derogatory term for one who becomes interested in one field, then another, never delving deeply into any of them, an amateur, or at best a generalist.
dimerous: Having all the parts of the flower in twos.
dimidiate: Halved diagonally, or as if one half was wanting.
dimorphic: Having two shapes; in ferns usually refers to fertile versus sterile laminae or portions of laminae.
dimorphism: The state of a plant or animal showing two forms or colors in the same population, e.g., snowshoe rabbits with winter white and summer brown coats. See also: polymorphism.
dimorphous: Occurring in two forms.
dioecious (alt. diecious): Unisexual, with male and female flowers on separate plants.
dip: A depression, as between two sand ridges.
diplecolobous: Describes cotyledons in a seed which are twice folded transversely.
diplochory: Describes seed dispersal involving two or more modes. For instance, a bird eats a fruit and disperses seed in it's droppings and these are later carried away by insects.
diploid: Having two sets of chromosomes.
diplostemonous: The stamens of the flower are arranged in two separate whorls, the outer one with stamens alternatewith the petals, the inner one opposite the petals.
direct seeding: Planting straight into soil where the plant is to grow rather than germinating seeds indoors and transplanting.
direct sunlight: Unobstructed sunlight. See also: skylight.
dirt: Soil.
disarticulating: Breaking apart at the joints when mature.
disbudding: The removal of the side flower buds around a central bud to induce extra-large blooms; or to selectively remove buds to conserve strength in a newly-transplanted perennial.
disc floret: One of the small tubular, actinomorphic florets which make up the central part of the flower head in Compositae, each with a pistil and stamens but generally no other conspicuous flower parts. See also: ray floret.
disciform: Round and flattened. See also: discoid.
disclimax: A one-time climax community which has been disturbed by people or their domestic livestock, such as a deciduous forest being replaced by a cropland.
discoid (adj. discoidal): 1. Resembling a disk. 2. In Compositae, a flower head without ray flowers, having disk flowers only.
discolorous: Refers to a leaf which has different colors on the two surfaces.
discontinuity (alt. disjunction): A gap in the range of a taxon. See also: distribution, disjunct.
discrete: Separate, distinct.
dish garden: A group of plants growing in a bowl or a shallow pot.
disjunct: Separated geographically, especially the population of a restricted area lying outside a main range.
disk: A development of the receptacle at or around the base of the pistil.
disk flower (alt. disc flower): In Compositae, the tubular flowers of the head, as distinct from the ray.
disk harrows (alt. disk): A field implement with disk-shaped blades which break up clods and level soil.
disoperation: Interaction between organisms in which one or all are harmed, as competition of maple seedlings, Acer, results in tall weak growth.
disparate: Unequal, not similar.
dispersal: 1. The actual passage of disseminules or organisms from one place to another. 2. The history of the movement of a group of organisms, such as the introduction of zebra mussels into the Great Lakes and down the Mississippi River. See also: migration, establishment, spread.
dispersion: 1. The pattern of distribution of individuals within a population, especially in prediction of probability. 2. In soil, the breakdown of aggregates, resulting in a single grain structure. Generally the more easily the soil disperses, the more it will erode.
disphotic zone: The depth in bodies of water where light is inadequate for photosynthesis but satisfactory for animal life.
dissected: Cut or divided into numerous lobes or divisions; a deeply cut leaf, the cleft not reaching to the midrib.
dissemination: The process by which propagules or organisms are spread.
disseminule: A plant part that can be easily separated from the parent plant, is dispersed, and can grow into a new plant. See also: diaspore.
dissepiment: A partition in an ovary, pericarp, or fruit.
distal: Towards the apex in position.
distant: Similar to parts that are separated and not overlapping.
distichous: In two vertical ranks.
distinct: Separate; not united; evident.
distributary channels: A system of forking streams flowing away from the main stream and not returning to it, as occurs in a delta or on an alluvial plain.
distribution: 1. The geographic range, continuous or discontinuous, of a plant, animal, or community. 2. Dispersalpatterns of occurrence of individuals in a taxon from a certain area, such as a) random distribution, poisson distribution, normal distribution; b) nonrandom above normal distribution, contagious dispersal, over-dispersion, hyperdispersion; and c) nonrandom below normal distribution, hypodispersion, or even-spaced distribution. The terms following each letter are synonyms.
distylous: Refers to a flower with two styles.
dithecal: Having two pollen sacs or cells.
diuretics: Herbal medicines taht can promote the flow of urine.
diurnal: Describes flowers which only open in daylight.
divaricate: Widely divergent.
divergence: The circumstance in which seres of similar origin become less like each other as succession moves toward climax. See also: convergence.
divergent: Buds which point away from the twig.
diversion dam: A barrier constructed for diverting part or all of the water in a streambed into a different watercourse.
diversity index: The mathematical statement calculated by dividing the number of species in a specified area by the number of individuals of all of these species.
division: 1. A major taxonomic grouping, ranking just below kingdom and above class. In the animal kingdom, it is usually replaced by the phylum. 2. Method of propagation for clump-forming plants through pulling apart fibrous-rooted clumps. 3. The removal of suckers from a parent plant for the purposes of propagation.
divisural line: The line down the teeth of a peristome, through which they split.
document: In botany systematics, this term can refer to herbarium specimens and equipment, as well as to the standard reference to written materials.
document retrieval: A more comprehensive term than 'literature retrieval' since it encompasses unpublished materials such as manuscripts, research notes, films, specimens, as well as published literature. See also: data retrieval.
documentation system: In botany systematics, this term covers the total strategy for identifying, citing, referencing, substantiating and authenticating, validating, verifying, and vouchering information used for a specific purpose in a taxonomic study.
dodder: Any of the annual parasitic wiry twining vines of the genus Cuscuta that lack chlorophyll and have tiny scales instead of leaves.
doldrums: The equatorial belt lying between the two trade wind belts that is characterized by calm or light variable winds and low atmospheric pressure.
doleiform: Shaped like a barrel.
dolomite (adj. dolomitic): 1. A mineral consisting of a calcium magnesium carbonate. 2. Limestone or marble rich in magnesium carbonate.
domatium (pl. domatia): A small structure located in the axils of the primary veins on the lower surface of leaves in some woodydicotyledons, usually consisting of depressions and being partly enclosed by leaf tissue or hairs.
dominant species: A species that exhibits ecologic dominance or social dominance over adjacent ones. See also: secondary species.
donga: A South African term for a gully with steep sides or a dry watercourse.
dormancy: Temporary cessation of growth.
dormant: In the state of suspended growth.
dormant oil (syn. dormant spray): Viscous solution containing pesticides and/or fungicides and applied to trees and shrubs in late fall and winter while the plant is dormant.
dorsifixed: Attached at the back.
dorsiventral (alt. dorsoventral): Having distinct back and front (or upper and lower) surfaces, or placed with reference to the back or front.
double (alt. double-flowered): Having more than the usual number of petals, often arranged in extra rows.
double citation: The occurence of two names at the end of a taxon, the first name, in parentheses, identifies the authorwho named the plant originally. The second name CITES the author of the new name.
double digging (syn. double trenching): A method of inverting soil where the richer, top layer of soil of one trench is placed in the bottom of a subsequent trench and covered with the soil of a lower level.
double fertilization: An exclusive process of angiosperms in which one male nucleus pollinates the egg nucleus to form a zygote, which develops into an embryo, while the other male nucleus joins with two other nuclei in the embryo sac to form endosperm, which can be found in corn, Zea mays, and other grasses.
double-toothed: Each tooth bearing smaller teeth.
double-worked: Twice grafted. The plant consists of the rootstock, an intermediate scion, and the upper scion.
down: An undulating, usually treeless upland plain having sparse soil.
downland: An Australian term for temperate grasslands.
downy: Covered with fine hairs.
downy mildew: A fungus forming grayish downy patches, usually on the underside of leaves.
drainage basin: Any of the largest natural subdivisions of the watersheds of a continent, such as the Mississippi, Columbia, and Colorado basins of North America.
drainage terrace: A graded embankment constructed with a relatively deep channel and low ridge, primarily for the runoff discharge from a hillside.
drawdown: The process of partially or completely lowering the water from a wetland with pumps or other mechanical devices. The purpose of drawdown is to manage vegetation and wildlife.
drepanium: A floral cyme shaped like a sickle.
dried flowers: Desiccated blossoms which retain shape and color over a long period of time, especially for winter arrangements.
driers: Blotters, newsprint or other materials which absorb moisture from plants in plant presses.
drift barrier: An open structure, like a wire fence, constructed across a stream channel to catch driftwood.
drift fence: A fence constructed to prevent livestock from wandering from their allotted range to another one, often used as an extension of natural barriers such as large rivers and cliffs.
drift ice: Parts of icebergs in the open sea beyond the areas of pack ice.
driftwood: Any wood from trees or structures which has floated in water.
drill seeding: Sowing seeds with an agricultural implement which makes furrows into which it drops seeds. See also: broadcast seeding.
drip irrigation (syn. bubbler irrigation): A method of irrigation where tubes or hoses, sometimes porous, are brought close to plants and water is allowed to trickle out at a very slow, but constant rate.
drip line: The line that could be drawn on the ground under a tree beneath the outermost tips of the branches. Rain flows off the tree at this point, so it is the area where roots congregate and the best point to place fertilizer, water, etc.
drip point (alt. drip-point, alt. drip-tip): 1. A leaf tip with an extension--acuminate, caudate, aristate--from which water drips during wet conditions. 2. A long drooping tip on leaves, particularly those of rain forest trees.
drip zone: The area around the base of a tree that lies below and within the circumference of the branches, etc., which forms its crown.
drooping: Erect at the base, but with the top part bending downward.
drought: A period of dryness; especially one that causes extensive damage to plants.
drought resistance (n. drought resistant): The capability of an organism to survive extended dry periods with little or no injury. See also: xeric.
drought tolerant: Capable of surviving for extended periods with little or no rainfall.
drumlin: An elongated or oval hill made up of glacial drifts, usually compact and not stratified, and often with the longer sides parallel to the movement of the glacier when the soil is dropped.
drupaceous: Resembling or of the nature of a drupe.
drupe: A fleshy or pulpy fruit with the inner portion of the pericarp (1-celled and 1-seeded, or sometimes several-celled) hard or stony.
drupelet: A diminutive drupe.
dry farming: 1. Agricultural operations in semiarid or arid regions without the use of irrigation. 2. A system of cultivation making heavy use of mulch and fallow periods to absorb and retain much of the rainfall.
dry stone: Building in stone without mortar.
dry wall: A wall built without the use of concrete, e.g., a stone wall.
drying frame: A structure, usually collapsible for easy transport, which holds plant specimens open to air and natural or artificial heat for rapid drying, thus preserving color and preventing mildew.
duckfoot: An agricultural implement with horizontal V-shaped blades that cultivate just below the surface of the soil without turning it over or burying crop residues.
duff: The partially decayed leaves, branches, etc., on a forest floor.
dune: A generally unstable mound or ridge of sand built up by winds, most common in deserts and along shores.
dune grass: Various species of Graminae with long roots, adapted to living on dry sand and used to stabilize dunes.
dune sand: 1. An area of tiny rock particles accumulated by wind action into mounds or hummocks, generally with little or no vegetation and undergoing continual redeposition. 2. Refers to rock particles with diameters of 0.1 to 0.4 mm. which have been heaped up by the wind, even if found far underground.
dung: Feces, animal droppings, scat.
duplicate: Folded twice.
duriherbosa: Vegetation that has perennial roots, but whose tops die back each winter, like those of grasslands.
durilignosa: Woody perennial vegetation with broad hard leaves, like chaparral.
dust: 1. n. A powdered chemical poison to kill insects or disease. 2. v. To apply the powder.
dust devil (alt. dust whirl, syn. remolino): An intensely whirling column of air caused by a bubble of hot air caught between two cooler layers of air. Dust devils range from a foot to a mile high (30 cm. to 1.5 km.) mostly in arid regions; they spin dust and debris but can also shake houses and slam birds into trees.
dust mulch: Keeping the surface of the soil from caking by repeatedly working it loose, preventing the germinationof weed seeds.
Dutch elm disease: A fungus spread by bark beetles that causes wilting and dieback on elms.
dwarf: 1. A plant that, due to an inherited characteristic, is shorter or slower growing than normal forms. 2. Dahlia varieties which normally do not produce plant growth over 24 inches in height.
dynamic equilibrium: A system that retains much the same condition because of the action of opposing forces which proceed at more or less equal rates. See also: balance of nature.
dysgenic (alt. eugenics): Refers to detrimental influences on the genetic properties of a community or population.
dystrophic: 1. Relates to or is caused by faulty nutrition. 2. Refers to a lake with high humus material, sparse bottom fauna, and low dissolved oxygen.
earth anchors: Steel pegs with semicircular bases to act as supports for larger trees, tying animals, etc.
earthworm: Any of the terrestrial annelid worms of the class Oligochaeta, especially those of the familyLumbricidae, that aerate and enrich soil.
earwigs: An insect that makes ragged holes flowers and leaves.
ebeneous: Black as ebony.
ecad (syn. ecophene, syn. environmental form): 1. A habitat form. 2. An organism showing somatic adaptations to a certain environment that are not hereditary. See also: phenotype, ecotype.
ecallose: With no callus.
eccentric: Not located at the geometrical center.
ecesis: The establishment of a plant or animal in a new habitat.
echard: Soil water not available for absorption by plants.
echinate: Beset with prickles.
echolocation: 1. Acoustic orientation such as that used in sonar. The ability of animals, e.g., bats, to emit high frequency sounds and then determine the whereabouts of themselves and other objects by hearing the corresponding echoes the sounds produce.
eciliate: Lacking cilia.
ecize: To become established, to spread, to invade. See also: ecesis.
ecocline: 1. The rate of increase or decrease of a variable character in the adaptation of a species, associated with environmental changes. See geocline. 2. The group exhibiting such a gradient. 3. A gradient of ecosystems along an environmental gradient, including both the gradient of natural communities and the complex gradient of environmental conditions. See also: coenocline.
ecologic dominance: The state in communities in which one or more species, by their size, number or coverage, exert considerable influence or control over the associated species.
ecological amplitude (alt. ecological valence): The variety of environmental conditions within which an organism can survive and replace itself, or a process can function. See also: tolerance, optimum, pessimum.
ecological bonitation: The numerical statement of well-being of an organism or group during a season or in a specific locality. See also: bonitation, biotic potential.
ecological efficiency: A mathematical statement of the ratio between the energy available to an organism or group or group processes, and the energy actually expended. For example, a bear may use less calories to hunt a rabbit during the summer than the calories gained from the rabbit, but winter hunting expends more than is gained, so it is more ecologically efficient for bears to hibernate. A 10 percent gain is average, 20 percent very good, 5 percent typical of the top of the food chain.
ecological equilibrium: See also: the balance of nature, dynamic equilibrium.
ecological equivalence: The case in which two or more species have enough similarities so that any could replace the other in a specified habitat. See also: ecological amplitude, niche.
ecological equivalent: An organism capable of replacing another in a habitat. See also: ecological equivalence, vicariation.
ecological factor: Any variable of the environment that impacts the life of one or more organisms. May be classified into A: climatic, physiographic, edaphic and biotic factors; or B: direct, indirect, and remote factors. See also: biotic, limiting factor, density dependent factor.
ecological longevity: Life span; the average length of life of a species under stated conditions.
ecological pyramid (alt. pyramid of numbers, Eltonian pyramid): The concept that in most food chains, the number of individuals decreases at each stage, with huge numbers of tiny individuals at the base and a few large individuals at the top, as displayed by millions of plankton, a moderate number of large fish, and a few eagles.
ecology (adj. ecological): The study of the relation of organisms to their environments.
ecorollate: Without petals.
ecorticate: Lacking a cortex.
ecospecies: A taxonomic species described in terms of its ecological characteristics, usually including two or more ecotypes capable of interbreeding.
ecostate: Lacking a costa.
ecosystem: An interacting complex of a community, consisting of plants and/or animals, and its environmentfunctioning as an ecological unit.
ecotone: A transition area between two adjacent ecological communities containing characteristic species of each, and sometimes, species unique to the area.
ecotourism: Travel undertaken to areas of unique natural or ecologic quality, or the provision of services to facilitate such travel.
ecotype (syn. ecological race, adj. ecotypic): A subdivision of an ecospecies that survives as a distinct population through environmental selectionand isolation; comparable to a taxonomic subspecies.
ectoparasite: A parasite living on the outside surface of a host, like a tick on a deer.
ectophagous: Refers to an animal that feeds from the outside of a structure, such as a rabbit eating bark from a shrub. See also: entophagous.
ectotrophic: Refers to fungi that grow on the surface covering of roots. See also: endotrophic, mycorrhiza.
edaphic community (alt. edaphic climax): A climax stage determined by factors related to the soil, pH, drainage, salinity, etc. See also: physiographic climax, biotic climax.
edaphic factor: A condition of the soil that is physical, chemical, or biological that influences organisms growing there. See also: biotic, climatic, ecological factor.
edaphology: The study of soils.
edaphon: 1. An organism that lives in the soil, such as a fungus, nematode, bacterium, etc. 2. The aggregate of organisms in the soil, with the exception of plant parts like roots. See also: plankton.
edentate: With no teeth.
edge: The border between two types of habitat, e.g., between forest and meadow, or stream and prairie, with vegetation of each type.
edge effect: The impact of two diverse communities where they abut, such as where a stream adjoins a prairie. See also: ecotone.
edger: A tool used to trim grass and its roots away from sidewalks and curbs.
EDTA (syn. ethylenediaminetetraacetic acid): The abbreviation for the white crystalline acid often used as a chelating agent.
eelworms: Microscopic organisms that enter the tissues of plants and cause rotting.
effective soil depth (syn. working depth): The extent to which roots of plants penetrate readily to reach water and nutrients.
effective temperature range: The spread between the highest and lowest temperatures in which an organism can survive and reproduce. See also: ecological amplitude, tolerance.
effluent: The outflow of water or other fluid. See also: influent.
egg: The nonmotile female sex cell (gamete).
egg-shaped: Shaped like an egg, with the broadest portion below the middle.
eglandular: Without glands.
eilliptic: Widest in the middle and tapering evenly to both ends.
elaiosome: A fleshy, protein-rich "food patch" on some seeds or fruits it is attractive to ants and thus aids dispersal.
elasticity: The capability of a strained body to recover its size and shape after deformation.
elater: A plant structure functioning in the distribution of spores, such bands which contract and expand when moistened or dried to disperse spores and the strap-shaped appendages of Equisetum spores.
electrolyte: A soluble substance capable of conducting ions when dissolved.
elements: Organisms typical of a certain region or habitat, but may occur outside of it, such as a group of prairiespecies found in the eastern part of the united States. See also: ecological factor, vicariation, ecological equivalence.
eligulate: Without strap organs.
ellipsoidal: Widest at or about the middle; margins are symmetrically curved, being narrowed to relatively rounded ends.
elliptic: Narrow at the ends and broad near the center.
elliptical: Oblong with rounded ends.
elongate: Much longer than wide.
eluvial layer: See A horizon.
eluviation: The removal of material from a specified soil horizon by leaching, either in solution or colloidal suspension. See also: illuviation.
emarginate: Having a shallow notch at the extremity.
emasculation: 1. In plants, the removal of male flowers or anthers to prevent self-pollination, such as removing tassels from corn, Zea mays, for hybridization. 2. In animals, castration, the removal of testicles, as done with some bulls to turn them into steers to produce tender meat.
embracing: Clasping at the base.
embryo: The rudimentary plantlet within the seed.
embryo sac: A structure inside the ovule of a flowering plant in which pollination occurs, and in which an embryo begins to develop.
embryogenesis: Formation and subsequent development of plumule, radical, and cotyledons in a plant.
embryoid: A mass of tissue that resembles an embryo.
embryotega: A callus near the hilum of certain seeds, which is detached during germination.
emergence: Refers to outgrowths on the surface of an organ, such as warts, prickles, etc.
emergent (syn. emersed): 1. Half uncovered. 2. In mosses, of the capsule, when the perichaetial leaves reach but do not overtop it. 3. An aquatic plant with its lower part submerged and its upper part extending above water.
emergent aquatic plants: Plants rooted in shallow water bottoms with the upper leaves and stems above the water surface.
emersed: Raised above the water.
emetics: Herbal medicines that can induce vomiting.
emigrant: One who moves from one area, emigrates, to live in another. See also: immigrant.
emigration: The process of leaving a locality more or less permanently.
emollients: Herbal medicines that can soften skin.
enantiostylous: Refers to flowers whose stamens bend to the left or right, with the styles in the opposite direction.
enation: An outgrowth on the surface of an organ.
encinal: Refers to a grove or forest of evergreen oaks.
enclosure: An area fenced or otherwise encircled to pen in animals, e.g., sheep. An exclosure is similarly treated to shut out other species, like coyotes, so the same area can be both an enclosure and an exclosure.
encystment: A state of inactivity of an organism surrounded by a protective case; metabolism is lowered while resistance is raised to unfavorable environmental conditions. See also: cyst.
end bud: A bud, or sometimes several, located at the end of the twig.
endangered plant: A species adjudged to be threatened with extermination.
endemic: Confined to a small area; limited in geographic distribution.
endemism: The occurrence of highly adapted plants or animals in an area. See also: endemic.
endocarp: The inner layer of a pericarp.
endochory (syn. endozoochory): Dispersal of an organism, particularly a seed, by an animal which carries it from one place to another, often in its digestive tract.
endogenous: Growing throughout the substance of the stem, instead of by superficial layers.
endoglossum: A crosswise projection from the back wall of a carpel to make it almost completely septate.
endoparasite (alt. endobiophyta): The existence of a parasite within an organism, like a tapeworm.
endophytic (n. endophyte): 1. Growing within the tissue of a plant; a plant that grows within another plant, like a fungusendoparasite. 2. A plant that can penetrate a rock, like a lichen.
endoplasma (syn. entoplasm, syn. endosarc): The inner granular layer of protoplasm in ovum development.
endosperm: The nutritive tissue in a seed of a flowering plant that surrounds the embryo. See also: perisperm.
endospore: An asexual reproductive body found mostly in bacteria.
endostome: The inner row of teeth of a peristome.
endothecium: The inner layers of cells of the capsule.
endotrophic: Refers to fungi that grow within roots. See also: ectotrophic, mycorrhiza.
endozoochore: A propagule like a seed that is dispersed by being carried inside an animal�s body, such as a cherry seed, Prunus, being swallowed by a bird and dropped in feces.
energy flow: The intake, conversion and passage of energy through an organism or ecosystem.
energy transformers: Plants and animals that process and pass on energy, originally transformed from sunlight by plants, from one organism to the next in a food chain. See also: energy flow.
enphytotic: Occurring regularly among the plants of a region, such as an endemic fungus. See also: epiphytotic.
ensiform: Shaped like a sword.
entire: Without toothing or division.
entomophilous: Pollinated by insects.
entophagous: Animals that feed inside of roots, dead leaves, etc. See also: ectophagous.
entropy: The degradation of energy, a measure of the degree of disorder of a system.
envelope (adj. enveloping): The surrounding part.
environmental clock: The influence of surroundings in initiating activities of organisms or certain processes, such as longer days initiating egg laying in birds.
environmental heterogeneity: The physical or temporal patchiness of the environment, created by disturbances like fire and storms, microclimates, soils, history, and random population variation.
environmental impact: A statement regarding new construction and the consequences it will have on the ecology of the area.
environmental resistance: The limiting influences of environmental factors upon the increase in numbers of individuals in a community. See also: biotic potential, reproductive potential.
Eocene: The second geological epoch in the Cenozoic era--the Tertiary period, that opened about 58 million years ago and lasted for 19 million years.
epappose: With no pappus.
epeirogenesis (alt. epeirogeny, alt. epirogeny): The deforming of the earth�s crust, producing continents, ocean basins, and great plateaus. See also: diastrophism.
epetiolate: With no petals.
epharmone: An organism which adapted to changes in its environment. See also: ecad, epharmony.
epharmony: The changes of processes or shape of structures by which an organism adapts to an altered environment. See also: adaptation, epharmone, ecad.
ephemeral (syn. transient): 1. Lasting one day, or more broadly, for a short time. 2. An herbaceous, perennial plant which dies to the ground after flowering and setting seed in spring or early summer.
epibenthic: Living on the surface of bottom sediments in a water body.
epibiotic: An endemic surviving from a former habitat; a relic.
epicalyx: A whorl of bracts outside the calyx.
epicarp: The outer layer of the pericarp or matured ovary.
epichil (alt. epichile, alt. epichilium): The terminal part of the lip in some orchids, distinctly different from the form of the basal part.
epicole (alt. epibiont): An organism which attaches itself to a host without either benefit or harm to the host, such as lichenson the bark of trees. See also: commensalism, epiphyte, parasite.
epicormic: Describes new growth (buds, shoots, or flowers) borne on the old wood of trees.
epicortical: Outside the bark.
epicotyl: The stem of a seedling between the cotyledons and the first true leaves.
epidemic: The pervasive spread of organisms which are parasitic, predatory, or damaging.
epidermis: The outermost layer of cells covering the plant.
epigeal: Of or relating to the emergence of cotyledons above the surface of the ground. See also: hypogeal.
epilia: A population of air plants, epiphytes. See also: epicole.
epilimnion: The upper layer of a lake which is disturbed by winds, lying above the thermocline. See also: hypolimnion.
epilithic: Growing on rocks.
epinasty (adj. epinastic): In plant physiology, the state in which more vigorous growth occurs in the upper surface of an organ, such as in an unfolding leaf, causing a downward curvature. See also: hyponasty.
epiorganism (alt. supraorganism): A natural group made up of similar individuals, like a hive of bees or a stand of maples, Acer. See also: community, population.
epipetalous: Borne on or attached to the petals.
epipetric: Growing on rock.
epiphragm: A membrane covering the mouth of the deoperculate capsule.
epiphyll: An organism that grows on leaves. See also: epiphyte.
epiphyllous: Growing on a leaf, usually through vegetative reproduction.
epiphyte (adj. epiphytic, syn. aerophyte): A plant growing attached to another plant, but not parasitic; an air plant.
epiphyton: A collection of organisms scattered over surfaces submerged in water, that may later become mechanically associated. See also: lasion, periphyton.
epiphytotic: Common, even epidemic, among plants in general, as some fungus diseases like mildew. See also: enphytotic.
episepalous: Borne on or attached to the sepals.
epispastics: Herbal medicines which can cause blisters.
epistasis: Suppression of the effect of a gene by another, nonallelic gene.
epithalassa: The upper layer of water above the thermocline, where stratification occurs because of water temperature in the ocean.
epithelium: Cellular tissue which covers a surface or lines a tube to assist secretion production and help assimilate nutrients.
epithet: The part of a scientific name designating a species or lower division of a genus. For example, in Cyranthus mackenii var. cooperi, mackenii is the species epithet and cooperi is the variety epithet.
epizoan: An epiphyte animal.
epruinose: Lacking bloom on the surface.
epsom salts: Bitter crystalline hydrated magnesium sulfate, sometimes used as a soil amendment.
equal: Of the same length, as in 'sepals equal petals.' It means that two plants are the same length--not that they are indistinguishable, as when two plants are so inseparable they are called tepals.
equidistant: The same measurement apart.
equilateral: Equal on both sides of an axis.
equitant: Astride; refers to conduplicate leaves which enfold each other in two ranks, alternating one above the other on opposite sides of the stem, as occurs on an iris.
eradicate (n. eradication, syn. exterminate): To remove entirely; to pull up by the roots.
erecto-patent: Midway between erect and patent.
erect: Vertical or upright
eremean: Belonging to regions of low, irregular rainfall.
erianthous: Having woolly flowers.
ericaceous: Refers to plants of the family Ericaceae that require an acid soil, generally with a pH of 6 or less.
ericoid: Like a heath.
erinous: Prickly, with sharp points.
erose: Irregularly cut away as if gnawed.
erosion (v. erode): Slow destruction of soil or rock by the action of water, wind, or ice.
errhines: Herbal medicines applied in the nose to promote discharge of mucus.
erumpent: Appearing to be ready to break through.
escape: An exotic plant that has spread from cultivation and grows successfully in the wild.
escarpment (alt. scarp): A long inland cliff or steep slope formed by erosion, often by waves, or sometimes by a fault.
esorediate: Lacking soredia.
espalier: A plant trained to grow flat against a wall or framework. To train a tree or shrub with its branches growing in a two-dimensional plane, flat against a building or fence.
essential oil: Any volatile plant oil used in perfume or flavorings.
estipulate (alt. exstipulate): With no bract at the base of the petiole.
estivation: Stagnating or otherwise nonfunctional during the summer months. See also: hibernation.
estrogenic: Herbal medicine that stimulates female hormone production or replaces it with plant hormones.
ethnobotany: The plant lore and agricultural customs of a people; the systematic study of such lore.
ethnopharmacology: The study and practice of medicines used by a people.
ethylene: A colorless flammable hydrocarbon gas occurring in plants, acting as growth regulator and fruit ripener.
etiolate (n. etiolation): To alter the natural development of a plant by excluding sunlight, often resulting in pale or bleached foliage. Etiolation is one method of layering for propagation; the shaded parts turn white or cream and develop no leaves.
eucamptodromous: Describes leaves having pinnate venation in which the secondary veins do not terminate at the marginsbut which gradually diminish inside the margin, connected to the superadjacent secondary veins by a series of cross-veins without forming prominent marginal loops. See also: acrodromous, brochidodromous, semicraspedodromous.
Euglenophyta: A taxonomic division containing euglenoids and Euglena. All are single-celled and found mostly in fresh water. They can contract the vacuole and have a single flagellum.
eukaryote: An organism composed of one or more cells containing visibly evident nuclei and organelles, including all organisms except viruses, bacteria, and cyanobacteria. See also: prokaryote.
eusporangiate: Refers to ferns having sporangia with walls thicker than one cell. See also: leptosporangiate.
eusporangium: A thick-walled sporangium originating from several epidermal cells.
eutrophic: Rich in dissolved nutrients, photosynthetically productive and often deficient in oxygen during warm weather.
evanescent: Disappearing at maturity.
even-pinnate: A pinnately-compound leaf lacking a terminal leaflet.
everlastings: Plants with flowers which hold their color and shape when dried.
evolute: Opened, unfolded.
evolution: Organic evolution is any genetic difference in organisms from generation to generation.
ex situ conservation: A conservation method that entails the removal of seed, pollen, sperm or individual organisms from their original habitat, keeping these resources of biodiversity alive outside of their natural environment.
exalate: Lacking an ala.
exalbuminous: Without albumen.
exappendiculate: With no appendages.
exarate: With grooves.
exarillate: Without an aril.
exceed (alt. exceeding): Refers to parts being compared in size where one is longer than the other.
excentric: Off center.
excrescence: Abnormal development, an outgrowth.
excurrent: 1. A growth habit with a single vertical trunk, the branches obviously secondary. 2. Describes a costarunning out beyond the lamina of a leaf. 3. Running out, as a nerve of a leaf projecting beyond the margin.
excurved (n. excurvature): Curved out and away from the central part.
exedra: 1. An open or colonnaded recess used for conversation, often semicircular and furnished with seats or a long bench. 2. A semicircular bench with a solid back.
exfoliate: To peel off or shed, as the thin layers of bark.
exfoliating: Cleaving off in thin layers.
exiguous: Small and narrow.
exindusiate: Lacking indusia.
exine: The outer layer of the wall of a pollen grain or spore.
exocarp: The outer layer or skin of a pericarp.
exogenous: 1. Grown or made outside the body. 2. Growing by annular layers near the surface, as bark. 3. Produced by growth from superficial tissue.
exostome: The outer row of teeth of a peristotne.
exotic: Not native, from another area.
exotic species (syn. alien species): A species that is not native to a particular geographic location, but may have become naturalized there.
expanded: Increased in area or size.
expectorants: Herbal medicines which can loosen mucus from the throat.
explanate: Flat, fanned out.
exserted: 1. Projecting beyond an envelope, as stamens from a corolla. 2. In mosses, elevated above the surrounding parts of the capsule, when the perichaetial leaves do not reach as high as their base.
exsiccated: Dried.
exstipitate: Lacking a stipe.
exstipulate: Having no stipules.
extant: Still in existence; not extinct.
extensile: Capable of enlargement or extension.
extinct: No longer living; no longer in existence.
extinction (syn. extirpation): The evolutionary end of a species or the loss of a species in a large area such as a state or country, caused by the failure to reproduce and the death of remaining members of the species.
extirpated: Literally, plucked up by the roots, exterminated. Often used to indicate that a species once lived in an area, and no longer does, usually because of changes in habitat.
extirpation: Wiped out, completely destroyed. Carries the connotation of differing from extinction in that it is more often due to human causes.
extra-axillary: Arising on the side of a stem outside of or opposite to an axil.
extract: A product prepared by removing essential constituents of a plant, such as oils for flavorings.
extrafloral: Beyond the essential parts of the flower, as nectaries, bracts, etc.
extrastaminal: Outside the stamens.
extratropical: Outside the tropics.
extravaginal: Describes a shoot which arises from an axillary bud and breaks through the sheath of the subtending leaf.
extrorse: Facing outward.
exudate (syn. sweat): Matter oozing from a surface.
exvaginate: Outside the sheath.
eye: 1. The center of a flower, if a different color from the rest. 2. A stem cutting with a single bud. 3. The undeveloped bud on a tuber.
eye-spot: A red cytoplasmic structure sensitive to light.
F layer: Sometimes used to designate the upper layer of soil litter whose origin and age can still be determined, although it is partially decomposed. See also: A horizon, H layer, L layer.
F1 hybrid: First-generation cross between two pure-bred strains. These hybrids produce seeds that are not true to type. See also: filial generation.
F2 hybrid: Second-generation cross between two F1 hybrids. See also: filial generation.
faciation: A part of a climax association which lacks some of the dominants of the normal association due to slight differences in environmental fundamentals.
facies: 1. A variation of the biotope, differing from the typical conditions in minor ways. 2. A deviation in a community like a dogwood, Cornus, or shrub facies in an oak forest. 3. The top to bottom appearance of a plant, including foliage, flowers, fruit, roots, etc. See also: faciation.
facultative: Capable of functioning under varying environmental conditions, e.g., a parasite which can survive with or without a host. See also: obligate.
facultative apomict: A plant that can reproduce either sexually or asexually (apomixis.)
fairy ring: A circle of mushrooms or toadstools growing from underground mycelium, which is usually surrounded by a ring of vegetation and is rather common in grasslands and sometimes in forests.
falcate: Scythe-shaped; curved and flat, tapering gradually.
fall line: A line connecting the points where rivers leave the uplands as they flow to the lowlands, indicated by sharper slopes and waterfalls.
fallout: The dropout from the air of solid materials, particularly in reference to radioactive dust from nuclear explosions.
fallow: Refers to cropland left standing without cultivation except to destroy weeds and accumulate water and nutrients for a later crop.
falls: Pendulous outer petals, as those found on an iris.
false annual ring: An extra growth ring produced in a season with a drought and then more rain.
family: A group of plants sharing common features and distinctive characteristics and comprising related genera; the taxonomic category above genus and below order.
fan-compound: A compound leaf with leaflets radiating from a single point; palmate-compound.
fan-lobed: Major lobes radiating from a single point; palmate-lobed.
fan-veined: Main veins radiating from a single point; palmate-veined.
fancy: Term used by the International Code of nomenclature for cultivated Plants. It is applied to cultivars, grexes, and hybrids, as opposed to natural species.
fangy: Describes forked roots.
farina: A waxy-appearing substance exuded from glands.
farinaceous (syn. farinose): Containing starch; powdery, starch-like.
farinose: Covered with a waxy, whitish powder; bearing farina.
fasciation: An abnormal flattening or coalescence of stems or leaf stalks.
fascicle: A close bundle or cluster.
fasciculate: In close bundles or clusters.
fasciculated root: A fibrous root where some of the branches are thickened.
fastigiate: Describes branches that are erect and near together, forming a columnar shape.
father plant: The species from which pollen was obtained to create a hybrid.
fauces (sing. faux): The throat of a flower in which the petals are united at least at the base, especially when the throat is distinguished in some way such as color, scales, etc.
fauna: A collective term, including all the kids of animals in an area or geologic period.
faunal region: An area with characteristic kinds of animals.
faveolate (alt. favose): Honey-combed.
favulariate: Finely ribbed, the ribs separated by zig-zag furrows.
feather-compound: Midribs of main leaflets branching from a central midrib at several points in a feather-like pattern; pinnate-compound.
feather-lobed: The main lobes more or less at right angles to the midrib, not radiating from a central point; pinnate-lobed.
feather-veined: Describes leaves whose veins all arise pinnately from a single midrib.
feces: Animal droppings, manure, scats.
fecundity: Productivity of an organism regarding fertility structures, like eggs, sperm, pollen, etc.
feedback: Any partial reversion of the effects of a given process to its source, such as leaves falling to the ground and furnishing calcium for uptake by the roots of the plant.
feeder root: One of the numerous small roots of a plant, through which moisture and nutrients are absorbed from the soil.
felted-tomentose: Woolly and matted, the hairs curling and tangling tightly to the surface.
fen: Low marshy ground containing peat that is relatively rich in mineral salts and is alkaline rather than acidic. It is usually found in the upper parts of old estuaries or around fresh water lakes, with vegetation quite different from that of moors.
fenestrate: Having openings, perforations or translucent areas.
Feng Shui: An ancient Chinese discipline combining town planning, environmental impact, architecture and interior decoration. Time, space, and action are designated to increase energy, harmony, healing, etc.
feral: Refers to an organism that escapes from cultivation or domestication and becomes naturalized.
fermentation: The chemical change of organic substances by organisms, such as yeast turning sugar into alcohol and carbon dioxide.
fern ally (pl. fern allies): A nonflowering, vascular plant belonging to one of the following classes: Equisetopsida (horsetails) Lycopdiopsida (club mosses, spike mosses, and quillworts) and Rhyniopsida (whisk fern).
ferruginous: Rust-color.
fertile: Capable of producing fruit; or productive, as a flower having a pistil or an anther having pollen.
fertility: 1. The reproductive capacity of an organism. See also: fecundity. 2. The property of soil that allows it to provide available nutrients and moisture to plants.
fertilization (alt. fertilisation): The union of male and female gametes.
fertilizer: Synthetic or natural organic substances providing essential plant foods. It most often includes nitrogen (N), phosphorus (phosphate; P), and potassium (potash; K).
fetid (alt. foetid): Carrying an unpleasant odor.
fibril: A short simple lateral branch of a lichen.
fibrillate: Finely fibrous or with hair-like lines.
fibrillose: 1. Furnished or abounding with fine fibers. 2. Having fibrils.
fibrous: Composed of or resembling fibers. Fibrous tissue: a tissue formed of elongated thick-walled cells.
fibrous root: A root that has no prominent central axis and that branches in all directions.
fibrovascular: Composed of woody fibers and ducts.
fiddlehead: One of the young unfurling fronds of some ferns that are often eaten as greens.
fidelity: The regularity with which a species occurs in certain plant communities, expressed in a five-part scaleranging from the most to least common: 5) exclusive, 4) selective, 3) preferential, 2) companion or indifferent, 1) accidental or stranger.
field border plantings: Vegetation established on the margins of fields to conserve soil and to provide food and shelter for wildlife, like native shrubs. See also: filter strip.
field crops (syn. cash crops): Agricultural production such as grains, hay, root crops and fiber in contrast to vegetables and fruits. See also: truck crops.
field equipment: Gear necessary to collect botanical specimens in the wild, such as maps, diggers and clippers, trowels, hand lens, collection bottles and bags, insect repellents, cameras, etc.
field expedition (syn. field trip): A journey planned to collect flora of a specific area or habitat.
field layer: The low stratum of plants like grasses, forbs and dwarf shrubs. See also: canopy layer.
field preservatives: Materials used to hold wet plant samples for long periods of time, or to hold plant specimens in tropicalareas. Examples are 2:3 commercial 40 percent formaldehyde and water; 1:2 formaldehyde and 70 percent alcohol; 40-50 percent alcohol; 1-2 percent aqueous solution of oxyquinoline sulfate. Specimens may be dipped, sprayed, or brushed with one of these, then enclosed in an airtight container.
field records (syn. field notes, syn. field data): A pocket-sized notebook which holds complete data on a field trip, including the precise location of places explored, dates, flora collected with any assigned numbers such as a tube of pollen or seeds, information on such things as a location in shade or sun, insects found on plants, moisture, bloom or fruit and their colors, and nearby plants, etc.
field strip cropping: A specialized strip cropping where crops are planted in parallel bands across a slope but do not follow contour lines; bands of grass or other close-growing species are alternated with the bands of cultivatedcrops.
field test (syn. field laboratory): An experiment conducted under regular field conditions, less subject to control than a precise contained experiment.
filamentous: 1. Made up of filaments or bearing them. 2. A form of lichen containing filamentous algae and fungi.
filial generation: In hybrid offspring, the first cross is designated as F1; the second cross as F2, etc.
filiform (syn. thread-like): Thread-shaped; long, slender, and terete.
filmy fern: A fern of shady places with exceptionally thin frond leaflets, usually of the family Hymenophyllaceae.
filter bridge: A land connection that remains in place for a demonstrated period of time, restricted in extent, limiting the kinds of organisms which can migrate over it, such as the Bering Strait in the Pleistocene period. See also: corridor, sweepstakes bridge.
filter strip (syn. greenway, syn. greenbelt, syn. beltway, syn. buffer strip, syn. buffer zone, syn. vegetated filter zone): A permanent strip of low plantings on the lower side of a field that is sufficiently wide and dense to slow the movement of runoff, allowing deposition of silt on the strip rather than its transport to a stream or pond. See also: field border plantings.
fimbriate (alt. fimbriated, n. fimbriation): Fringed; having the edge or extremity bordered by slender processes.
fimbrillate: Having a minute fringe.
fine-textured soil: A soil that consists mostly of silt and clay, with little or no sand or gravel.
fines: Materials from rock and organic extraction that are often carried away by the action of wind or water.
fire control line: A designated margin along which a wildfire, if possible, is not allowed to pass; often backfires are started here.
fire hazard: The risk level of a fire starting under prevailing climatic conditions, often simply low, average, or high.
fire towers: Structures in forests which rise above the tree tops and are staffed during fire danger periods.
fireblight: A bacterial disease of rose family.
firebreak: A strip of land where flammable materials have been removed to check or stop a creeping or running wildfire.
firn: Granular snow, usually compacted; a ski term for last year’s snow. See also: neve.
first bottom: The flood plain that is closest to a stream or is at the lowest elevation above a stream; the first to be flooded.
firth: A term commonly used in Scotland that means a long narrow arm of the sea or the mouth of an estuary.
fishway (syn. fish ladder): A sloping structure over which water is allowed to flow, to help fish in breeding season to ascend a stream which forms a waterfall.
fissile: Easy to split.
fissured: Having deep cracks.
fistular: Hollow and cylindrical.
fitness: The level of adaptation of an organism to its environment.
fitness of environment: The suitability of a habitat for preserving life.
flabellate: Fan-shaped.
flachmoor: Wasteland with a flat to slightly depressed surface, with peaty soils that are poor in salts and have an acidic reaction.
flagellates: Cells with flagella but no cell wall.
flagelliflorous: Bearing flowers at the ends of long, pendulous branches.
flagelliform: Whip-like in shape.
flagellum (pl. flagella): Tiny whip-like appendage that is capable of movement.
flaky: Bark with loose scales which are easily rubbed off.
flank: The side of anything, like the west flank of a mountain.
flats: Low, exposed land of a lake delta or a lake bottom; or often brushy land along the floodplain of a stream.
fleshy: Succulent or juicy.
flexible: Easily bent or twisted.
flexuose (alt. flexuous): Zigzag; bending from side to side; wavy; sinuous.
floating-leaved plants: A free-floating plant such as duckweed, Lemna; or one with roots in the water bottom but having leaves that float on the surface like the water lily, Nymphaea.
floccose: Clothed with locks or flocks of soft hair or wool.
flocculate (n. flocculation): 1. To cause to form lumps or masses, as in soil. 2. The rapid precipitation of large amounts of a solute out of a solvent.
flocculation: The coming together of suspended colloidal material or very fine particles like silt, into larger masses called floccules.
flocculent: Resembling wool especially in loose fluffy organization.
floodplain (alt. flood plain): The almost level land forming the floor on either side of a stream in a valley, often subject to flooding.
flora: All plants as a group; the particular plants of a region.
floral: Belonging to or associated with a flower.
floral cup: A cup-shaped or tubular part of a flower.
floral envelope: The perianth.
floral region (alt. floristic region, alt. floristic area): An area with a degree of homogeneity of species existing because of similarities in topography, climate, etc., in the region.
floral shovel: A round-pointed shovel.
floral snip: Scissors specialized for delicate jobs, such as harvesting herbaceous flowers.
floral tube: A tube formed in some flowers by the fusion of the perianth and the stamens.
floret: A small flower, usually one of a dense cluster. See also: flowerhead.
floricane: A biennial stem typical of Rubus, which grows the first year, and bears fruit and dies the second year.
floriculture: The cultivation of ornamental plants, especially flowering plants.
floriferous: Flower-bearing; blooming profusely.
florigen: A hormone which appears to be produced in the leaves, then translocated to apical meristems where it initiates the formation of flowers.
florist: One who sells flowers retail, usually obtaining the blossoms from a middle man.
floristic composition: The array of plant species that occurs in a community or region.
floristic element: Species that are characteristic of a designated region but may also occur in a different one, e.g., a midwest united States species growing in the upper levels of the Smoky Mountains is a midwest element of those mountains.
floristic study: A complete listing of the plants from a given jurisdiction, e.g., a state, or from habitats such as lake shores or marshes, or a listing of all of the species within a genus or other delineation.
floristic territory: A geographic area characterized by the common occurrence of a number of more or less endemicspecies, although other species may be present.
flower: 1. The reproductive structure of a flowering plant consisting of a pistil and/or stamen, and usually including petals and sepals. 2. Often applies to the reproductive organs of mosses.
flower bed: An area planted with flowering plants and surrounded by lawn, structures, etc.
flower box (alt. window box): A container attached to a porch railing or window sill planted with colorful species.
flower bud: The bud which contains a flower or a cluster of flowers.
flower head: A group of florets.
flower induction: The initiation of the production of flowers, possibly stimulated by florigen.
flowering dates: The period(s) of the year when a species can be expected to produce blossoms.
fluctuation: A relatively atypical departure from more average conditions, but still within normal limits.
flume: 1. In the united States, a ravine or gorge with a stream running through it. 2. A man-made open conduit, often made of wood or concrete, for the purposes of irrigation, power, etc. It operates by transporting liquids across a stream or depression which intersects the course of the conduit.
flush cut: A pruning cut to remove a tree limb in which the cut is completely flush with the tree. The resulting scar is too large to heal efficiently.
fluted: With rounded, longitudinal grooves or ridges.
flyway: A migratory pathway of birds, like the Mississippi flyway following the Mississippi River.
foehn: A Swiss term for a wind blowing down a mountainside, especially if it is warm for the season. See also: chinook.
fogger: A device used to apply a pesticide in suspension in water or air.
foliaceous: Leaf-like in texture or appearance.
foliage: The leaves of a plant taken collectively.
foliar diagnosis: Evaluation of the nutrients in a plant, or the plant nutrient requirements of a soil, by analyzing the leaves.
foliar feeding (alt. foliar fertilizing): The process whereby plants are fertilized by application of liquid onto the leaves rather than through the soil.
foliate: Bearing leaves.
folic acid (syn. pteroylglutamic acid): A member of the B vitamin complex, found mostly in the leaves of plants.
foliolate: Bearing leaflets.
follicular: Like a follicle.
food chain: An ever increasing progression of edibles, from microscopic plankton which are eaten by small animals, which in turn are eaten by larger animals, and so on, up to the largest predator. The animals all die and are digested by fungi and bacteria, starting the chain all over again.
food cycle (alt. food web): All the interconnecting food chains in a community.
food niche: The location of a particular organism in a food cycle.
food pyramid: A theoretical graphic illustration showing the immense number of producer organisms at the base and the progressively decreasing numbers of herbivores and carnivores toward the peak.
forage acre: A theoretical concept demonstrating the quantity of feed on an acre of land which is totally coveredwith vegetation and completely utilized under proper management.
forage acre requirement: The number of forage acres needed for the maintenance of X numbers of mature grazing animals for a specified period of time.
forage ratio: A mathematical statement regarding the percentage of a prey species present in the food of a predator species, which is divided by the percentage of the prey species present in the habitat.
forage volume: 1. The total parts of plants that can be reached by grazing or browsing animals. 2. A measure of the yield of feed, the total amount produced on a certain range during a year.
foraminifers: Small marine animals with calcareous shells which are perforated with minute holes for extension of pseudopods.
forb: A nonwoody plant other than grass, sedge, or rush. See also: herb.
foredune: A low pile of sand, often held in place by dune grass, bordering the shore of a sandy lake or sea.
forensic: Relating to the application of scientific knowledge to legal problems, as a forensic entomologist helps place time of death by developmental stages of insects on the deceased.
foreshore: That portion of the beach occupied on a daily basis by tides.
forest cover: The living plants and dead organic matter on the floor of a forest, sometimes restricted to only the plants. See also: basal cover, duff.
forest edge: The boundary or ecotone of a forest where it meets with some other kind of vegetation such as a marsh.
forest floor: The deposits of plant material such as dead leaves and branches on the ground in a woodland. See also: duff, forest cover.
forest fragmentation: The continuing splitting of large forested areas by highways and residences, which changes the habitat. It affects the acclimation and persistence of wildlife and indigenous plant species.
forest influences: A total of the effects or reactions of a woodland on the environmental conditions, such as providing duff as compost, and maintaining uniform stream flow.
forest type: A stand of trees that is fundamentally similar throughout and can be predicted to occur elsewhere under comparable conditions. It includes temporary, permanent, climax, and cover types.
forked: Divided into nearly equal branches.
forma (abr. f.): The rank of taxa below variety; the narrowest taxon; a plant which retains most of the characteristics of the species, but differs in some way such as flower or leaf color, size of mature plant, etc. A forma is added to the specific binomial and preceded by "f.", such as rubra in the epithet Cornus florida f. rubra.
form: A small but constant variation within a population of plants, such as a white-flowered plant in a normally purple-flowered population.
formenkreis: A series of related forms pinpointed geographically that originated entirely or primarily by geographic isolation. See also: speciation, evolution.
fortnight: Two weeks, fourteen nights.
fossorial: Refers to animals that burrow in the soil, e.g., voles.
foundation planting: Those shrubs and flowers planted close to the house which make a smooth transition to the surrounding landscape.
founder principle: The theory that an isolated population, perhaps on an island or cut off in other ways, holds a small number of settlers with a limited gene pool, which is the first step toward new species.
foveolate (alt. foveate): Honeycombed; pitted.
fox fire: Phosphorescent light caused by a fungus on decaying wood.
fragment: Refers to communities, a stand so small that it lacks sufficient species composition and other characteristics associated with a community. See also: population.
fragmented structure: Refers to a soil composed mostly of particles that exhibit well defined faces and edges. See also: granular structure.
fragrance garden: A garden consisting of flowering plants and herbs noted for pleasant odors. Often used in recreational/educational areas for the visually impaired, and for residential yards used at night.
frass: Debris and fecal matter produced by insects.
free-central: Describes placentation where the ovules are borne on a free-standing central placenta within the ovary.
French drain: A channel leading from an overly wet area or to a dry area to transport water as needed. The deep narrow channel is filled with stone to allow water to pass, but to also provide a firm surface.
frequency (alt. frequence): 1. The level of regularity found in the distribution of individuals of a species in an area, especially in a stand. See also: constancy, stand. 2. A general term for a group of plants with more or less regularity of physiognomy, composition, and habitat. See also: community, association.
frequency class: One of the small groups into which a frequency index of the various species in a stand may be classified.
frequency index: A mathematical expression using the percentage of frequency; e.g., a species inhabiting 16 of 20 sample areas has a frequency index of 80 percent.
friability: Desirable texture of soil that allows it to crumble into small particles rather than large clods.
frigid zone: That part of the earth lying north of the arctic Circle or south of the Antarctic Circle. See also: temperate zone, tropic zone.
frigorideserta: Tundra; cold arctic or antarctic areas, and alpine communities.
fringed: Fimbriate.
fringing forest: A strip of woodland along a stream or body of water. See also: gallery forest.
frondose: Leafy, frond-like.
front: The border between warm and cold air masses at the earth’s surface.
frost: 1. A covering of minute ice crystals on a cold surface. 2. The temperature low enough for this to occur. See also: hard frost, light frost.
frost resistance: The capacity for survival of a plant when ice crystals form in the cells. See also: hardening.
frostless season (alt. frost free days): The time between the last spring frost and the first autumn frost.
fructiferous: Capable of bearing fruit.
fructification: The act or organs of fruiting.
frugivore: An animal that eats fruit.
fruit: 1. The mature ovary of a seed plant. 2. Sporangia; often applied to the sporophyte.
fruit harvester: A basket made of wire with curved tips, fastened to a long handle, to catch fruit and pluck it from the ground.
fruit-dot: A sorus.
fruiting spur: On a fruit tree, a short twisted branch with rings around it, which flowers and produces fruit.
frutescent (alt. fruticose): Resembling a shrub.
fruticeta: Vegetation type made up of scrubby forest.
fruticose: Shrub-like, bushy, with many stems rather than a single trunk; a form of lichen which appears shrubby or hair-like.
fruticose lichen: A lichen with a thallus more than 10 cm. (4 inches) tall, like Cladonia rangiferina, reindeer moss.
fucoid: Resembling a seaweed, especially Fucus.
fugacious: Falling or fading very early; short-lived.
fully double: Flower heads with multiple rows of ray florets; the disc florets are immature and completely covered by the central rays when the flower is at its prime stage.
fully revolute: Rolled backwards with margins touching or overlaping.
fully stocked: Refers to a stand that contains as many trees or other materials of the species and ages as the site can support. See also: overstocked, understocked, carrying capacity.
fumarole: A hole in the earth from which heat and gasses escape under pressure.
fungicide (adj. fungicidal): An agent to inhibit the growth of, or destroy fungus.
fungivorous: Refers to organisms that eat fungi.
fungoid: Resembling a fungus, mushroom-shaped.
fungus: A nonflowering plant of the kingdom Fungi, all lacking chlorophyll.
funicle (alt. funiculus): The free stalk of an ovule or seed.
funiculus: The stalk of the ovary in plants.
furfuraceous: Covered with bran-like scales.
furrow dam: A small earth blockade for holding water within a furrow. See also: lister.
furrowed: With channels running lengthwise, including both sulcate grooves and striate thread marks.
fusarium (pl. fusaria): Any of the pathogenic, imperfect fungi of the genus Fusarium which infect both plants and animals.
fuscous: Dusky, grayish-brown.
fusiform: Spindle-shaped; swollen in the middle and narrowing toward each end.
fusiform root: A taproot which tapers at the top as well as the bottom, like a white radish.
fusoid: Somewhat spindle-shaped.
fynbos: A South African term for sclerophyll vegetation on plateaus and mountains, similar to macchia of the Mediterranean region and chaparral of California.
galactosidase: An enzyme which cuts the glycosidic bond between the sugar galactose and molecule. There are two types, the alpha galactosidases and the beta galactosidases.
galea: A hooded or helmet-shaped portion of a perianth, as the upper sepal of Aconitum, and the upper lip of some bilabiate corollas.
galeate: Helmet-shaped; having a galea.
gall: An abnormal growth or swelling caused by insects, fungus, etc.
gallery forest: A narrow woodland developed along a stream because of constant and sufficient moisture through a grassland or other open vegetation.
galls: Corky swellings.
gametangium: The organ producing the gametes.
gametophyte (syn. gametophore): That part of the plant which bears the gametes or sexual cells. In mosses, all of the plant except the "fruit," or seta and capsule.
gamopetalous: Having the petals of the corolla more or less united. See also: polypetalous.
gamophyllous: Composed of coalescent leaves or leaf-like organs.
gamosepalous: Having the sepals united.
garden: The proper term for landscaped area or yard. To many Americans, the term refers only to the vegetable garden.
garden hoe: A lightweight hoe for weeding, etc., in home or truck gardens.
garrigue (syn. phrygana, syn. batha): Stony or sandy--often over-grazed--hillsides, similar to maquis, but hotter and drier still.
gazebo: A free-standing roofed structure usually open on the sides.
gelatinous: Having the consistency of jelly or gelatin.
geminate: Equal, in pairs.
gemmiferous (syn. gemmiparous): Bearing gemmae.
gemmiparous: With vegetative buds.
gene bank: A facility existing for the ex situ conservation of seeds, tissues, or reproductive cells.
genetic diversity: Variability in the genetic makeup of individuals within or among species; the hereditary variation within and among populations.
genetic dominance: The influence exerted by a dominant gene or allele, like wrinkled seeds being dominant over smooth.
genetic drift: Random changes in isolated populations, or in the frequencies of certain genes, which cannot be accredited to selection, mutation, or migration. See also: natural selection.
geniculate (alt. genticulate): Bent abruptly, like a knee.
geniculum: A sharply bent joint or node.
genotype: The genetic constitution of an organism, acquired from its parents and available for transmission to its offspring. See also: phenotype.
genus (pl. genera): A group of closely related species. The taxonomic category ranking above a species and below a family.
geophyte: A plant whose perennating buds are found underground, usually attached to a bulb, corm, tuber, etc.
geotropism: An organism's growth determined by the force of gravity, as roots growing downward and stemsupward.
germ cell: A reproductive cell, or gamete, or a cell that will develop into a reproductive cell, such as a spermatocyte or an oocyte.
germ plasm: The cytoplasm of the germ cell, particularly that containing the genetic material.
germination: The sprouting of a plant seed.
germination rate: The proportion of seeds in a given seed lot that are likely to germinate under favorable conditions.
germplasm: The genetic material with its specific molecular and chemical makeup that comprises the physical foundation of the hereditary qualities of an organism.
gesneriad: Any of the mostly tropical plants of the family Gesneriaceae, including gloxina and African violets.
gibberellic acid: A hormone used to promote plant growth, especially that of seedlings, and obtained from the fungusGibberella fujikoroi.
gibberellin: Any of several growth-regulating plant hormones produced by seeds, mosses, ferns, algae, and fungi.
gibbosity: A swelling of moderate extent and asymmetrical character, chiefly at or near the base of an organ.
gibbous: Protuberant or swollen on one side.
girdle: 1. To intentionally remove a circle of bark and cambium from a tree in order to kill it. 2. To encircle tightly, eventually choking of nutrients and causing the death of a plant or limb.
girdling root: A root that has become wrapped around the trunk of the plant which inhibits the uptake of nutrients; usually occurring in plants grown in containers.
glabrate: Somewhat glabrous, or becoming glabrous.
glabrescent: Becoming glabrous in age.
glabrous: Smooth; not rough, pubescent, or hairy.
glade: An open grassy area surrounded by woods.
gland-dot: A tiny gland or pore, usually secreting fluid.
glandular: Bearing glands or of the nature of a gland.
glandular-toothed: Teeth that bear glands.
glaucescent: Somewhat glaucous, lightly coated with a fine bloom.
glauconite: A greenish mineral consisting of a silicate of iron, magnesium, aluminum or potassium found in greensand and often used as a fertilizer or soil supplement.
glaucous: Bluish white; covered or whitened with a very fine, powdery substance.
globose: Globe-shaped.
globular: Spherical or nearly so.
glochid: A barbed hair or bristle.
glomerate: Compactly clustered.
glomerule (adj. glomerulate): A small compact cluster.
glucose: A monosaccharide sugar widely found in plant and animal tissue.
glumaceous: Furnished with or resembling glumes.
glume: A chaff-like bract; specifically one of the two empty chaffy bracts at the base of the spikelet in the grasses.
glutinose (alt. glutinous): Viscid, sticky.
glycosidic bond: A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom.
Golgi complex (syn. Golgi apparatus, syn. Golgi body): A cytoplasmic organelle that consists of a stack of smooth membranous saccules and associated vesicles and that is active in the modification and transport of protein.
grade adjustment: Changing existing levels of ground areas.
grader (alt. roadgrader): A truck which smooths the surface of gravel roads and raw soil.
graft: To insert a section of one plant, usually a shoot, into another so that they grow together into a singleplant; the plant formed from grafting.
graft chimaera (alt. graft hybrid): The mingling of tissues belonging to the stock and scion through grafting in a nonsexual manner. These are designated in formulae by a crucifix type cross which appears as "_", e.g., _Laburnocytisus adamii (Laburnum anagyroides _ Chamaecytisus purpureus).
grafting: Method of propagation for trees and shrubs by inserting a section of one plant, usually a shoot, into another so that they grow together into a single plant.
graminaceous: Related to grain-bearing plants.
granular structure: Refers to a soil composed mostly of particles that exhibit rather indistinct faces and edges. See also: fragmented structure.
granulose: Composed of or appearing as if covered by minute grains.
granum (pl. grana): Structures in chloroplast that consist of thylakoids.
grass catcher: A container fitted onto a lawn mower to catch grass clippings while mowing.
gravitational water: Water held in large pores in soil that drains away or leaches when underdrainage is free.
gray mold: A fungus disease characterized by the gray hairy appearance of affected parts.
graze: 1. To feed on grasses and forbes. 2. Grasses and forbes.
green drought: A weather term describing a period of enough rain to keep shallow-rooted plants alive, although the water table continues to recede.
green manure: The plowing under of living plants so that their decay will increase the humus of the soil.
greenhouse: An enclosed structure, usually made of glass (to trap solar radiation), that allows for the regulation of temperature and humidity and is used to propagate and grow plants.
greensand: A sand or sediment that consists largely of dark greenish grains of glauconite, usually mixed with clay or sand.
gregarious: Growing near together or clustered, but not in close tufts or mats.
grex: A group name for all plants derived from crossing the same two or more parent species; the herd or hybrid swarm.
grooved: A general term for sulcate or striate.
grotto: An artificial recess or structure made to resemble a natural cave, often having running water.
ground layering: Another name for tip layering.
groundcover: A plant with a low-growing, spreading habit, grown specifically to cover the ground.
groundwater: Subsurface body of water body in the zone of saturation; That portion of the water beneath the surface of the earth that can be collected with wells, tunnels, or drainage galleries, or that flows naturally to the earth's surface via seeps or springs.
group: An artificial category between species and cultivar used to designate a collection of cultivars with similar parentage.
growth regulator: A chemical that sp.s or slows plant growth or maturation.
grub hoe: A heavy weight hoe for digging roots, etc.
guard cells: The two cells that bound a stoma and by opening and closing allow gas exchange.
guard petals: The outer petals of a rose, especially those that are larger than and also enclose the inner petals.
guides: A term applied to the large parenchyma cells seen in the cross-section of the costa of many Dicrana.
gulch: Western U.S. term for a deep cleft, especially one that is formed following a torrent; a ravine. See also: arroyo, gully, valley.
gully (adj. gullied): A miniature valley eroded by water. See also: ravine, valley.
guttation: 1. The formation of drops of water on plants from moisture in the air. 2. The exudation of liquid water from the uninjured surface of a plant leaf. 3. The process of water being exuded from hydathodes at the enlarged terminations of veins around the margins of the leaves.
gymnosperm: A seed plant that bears naked seeds, i.e., seeds without ovaries. These include conifers, cycads, ginkgos, and ephedras.
gymnospermous: Bearing naked seeds, without an ovary.
gymnostomous: Without a peristome.
gynandrium: A structure in which the stamens are attached to the pistil.
gynobase: An enlargement or prolongation of the receptacle bearing the ovary.
gynobasic: Describes a style arising from the base of the gynoecium.
gynodioecious: Having both bisexual flowers and female flowers, but on separate plants. See also: dioecious.
gynoecium: The pistil or pistils considered as a group.
gynomonoecious: Refers to a plant that produces both perfect flowers and female flowers.
gynophore: A stalk bearing the gynoecium above the level of insertion of the other floral parts.
gynosporangium: The receptacle in which gynospores are developed.
gynospore: One of the larger (female) reproductive bodies in the Isoetaceae, etc.
gynostegial corona: The collective term for the staminal and interstaminal coronas (in Asclepiadaceae), both of which are associated with the gynostegium. See also: staminal corona, interstaminal corona.
gynostegium: The crown of united stamens in milkweeds, Asclepidaceae.
gynostemium: The compound structure resulting from the union of the stamens and pistil in the Orchidaceae.
gypsum: A mineral consisting of hydrous calcium sulfate that is used as a soil amendment to add sulfur and calcium and counteract salt damage. It is added to cement to regulate setting.
h & s: The abbreviation for the height and spread of a plant.
habit: The general appearance of a plant.
habitat: The natural dwelling place of an animal or plant; the type of environment where a particular species is likely to be found.
haft: Narrow stalk-like base to some petals, as those on irises.
hair: 1. An epidermal outgrowth composed of a single elongated cell. 2. In lichens, a multicellular outgrowth from the cortex.
hairy: Covered with hairs; pubescent, hirsute, etc.
half-inferior: Describes an ovary partly below and partly above the level of attachment of the perianth and stamens.
halophyte: 1. A plant adapted to living in highly saline habitats. 2. A plant that accumulates high concentrations of salt in its tissues.
hamate (syn. hamulose): Curved like a hook.
hand axe: A similar tool intermediate in size between a hatchet and an axe.
hapaxanthic: Reproducing once only at the end of the plant's life.
haptotropism (adj. haptotropic): An orientation response of an organism to stimulation by touch.
hard construction (alt. hard landscaping): The nonliving elements of a landscape installation, made of wood, brick, concrete, etc.
hard frost: A frost where both the air and the soil has dropped below freezing. Many plants can survive a light frostbut cannot survive a hard frost.
harden off: To gradually accustom a plant to more difficult living conditions, e.g., moving a plant from the greenhouse to the partial shade of a tree before planting it in a garden.
hardening: 1. The process of gradually taking plants into a harsher environment, e.g., from the hothouse to the garden. 2. The term can also mean sustaining a plant from summer to winter, which may include a three-staged process: 1) phytochrome clocks signal the shortening days with a color change. 2) Growth ceases, carbohydrates are transported to the roots, and abscisic acid forms at the union of leaf and stem, dropping the leaf and healing the wound. The dropped leaves serve as mulch and protect the roots from excess cold in the winter, while cell walls toughen. 3) A smooth ice forms around the cells without rupturing them, a process called vitrification.
hardiness: The ability of a plant to withstand winter cold and summer heat.
hardpan: A layer of soil sufficiently clogged with clay or other particles which often prevents the penetration of water and shrub or tree roots.
hardscaping: Man-made objects of a landscape as opposed to natural objects like plants and streams.
hardware cloth: A metal fabric that is more coarse than a window screen but finer than fencing.
hardwood: A term applied to broad-leaved trees as opposed to conifers.
hardwood cutting: Cutting taken from a mature woody stem for the purpose of propagation.
hardy: A term used regarding plants that describes their ability to withstand cold. It does not mean that the plant is long-living, pest resistant, or drought tolerant.
harrow: A field implement with semicircular teeth that breaks up clods and levels soil. 2. To break up and level the soil surface by dragging over it an implement of the same name designed for that purpose.
hastate (syn. halberd-shaped): Like an arrow-head, but with the basal lobes pointing outward nearly at right angles.
hatchet: A short axe.
haustorium: A specialized absorbing structure of a parasitic plant through which it obtains chemical substances from its host.
head: 1. A dense cluster of sessile or nearly sessile flowers on a very short axis or receptacle; heart-shaped. 2. Ovate with two rounded lobes and a sinus at the base; commonly used to define such a base. 3. The number of animals, e.g., 40 horses, that would be counted by a farmer/rancher as 40 head of horses, or merely 40 head.
head back: To cut back the main branches of a woody plant severely.
heading back: Cutting a branch back to a bud or side branch to increase the number of shoots, making the plant thicker and bushier.
heartwood: The harder and often darker colored wood that forms the interior of a tree trunk or branch.
heath (alt. heathland): An extensive area of rather open uncultivated land usually with poor coarse soil and covered with low shrubs, such as those of the genus Erica; a moor.
heavy soil: An imprecise term which refers to soil in which the particles are packed closely together with little air or water available to the roots of the plant.
hedge: A fence or boundary formed by a dense row of shrubs or low trees and often given a formal appearance by frequent trimming.
hedge shears: Specialized heavyweight scissors for shaping woody plants into hedges.
hedge trimmer: A hedge trimmer is a gardening tool or machine used for trimming (cutting, pruning) hedges or solitary shrubs (bushes). Different designs as well as manual and powered versions of hedge trimmers exist.
hedgerow: A row of shrubs or trees enclosing or separating fields, often on a low berm of earth.
heel: The portion of old wood at the base of a cutting.
heel in: To temporarily store plants with their roots in moist soil or sawdust to hold them for several days or weeks until they are able to be planted properly.
heirloom garden (syn. antique garden): A garden created using plants that were in cultivation in the past, usually from a particular period.
heirloom plant: A plant that was developed and in cultivation sometime in the past.
helicoid: Having the shape of a flattened coil, often describing a cyme.
heliophilous: Adapted to, or capable of, growing in full sunlight.
hemiepiphytic: Remaining rooted in the ground but climbing tree trunks.
hemiparasite (syn. semiparasite): A parasite which lives on and derives part of its nourishment from its host, but also conducts photosynthesis; for example, the mistletoe.
hemostatic: Herbal medicine that can stop bleeding.
hemp: 1. The course fibers used to make cordage derived from plants of the genus Cannibis, or other similar plants. 2. A plant of the genus Cannibis.
herb garden: A garden consisting of culinary and/or medicinal herbs and often having an ornamental design.
herbaceous: 1. Having little or no woody tissue; leaf-like in color and texture. 2. Refers to a plant which dies back to the roots each year during winter, as opposed to a plant which remains green all winter.
herbal: 1. A book about herbs, usually illustrated. 2. Of, or relating to, herbs.
herbalism: The cultivation, collection, study and use of herbs, particularly for medicinal purposes.
herbalist: One who practices herbalism.
herbarium: 1. An organized and cataloged collection of plant specimens. 2. A specialized room or building with constant levels of temperature, moisture and restricted light where plant samples are stored in a designated pattern in large light proof cabinets, allowing samples to remain useful and to be retrieved for study and comparison for centuries.
herbarium glue (alt. herbarium paste): An adhesive which minimizes cracking, discoloration, and shattering with age, used in fastening plant specimens to the herbarium sheet.
herbarium sheet: Lightweight white card stock used as backing for herbarium specimens, in a standard size of 11 X 16 inches (28 X 40 cm.).
herbicide: A substance that is fatal to plants, or to selected plants.
hermitage: A usually small building provided for contemplation, especially of nature.
hesperidium: A relatively large fruit, pulpy inside with a hard rind outside, such as citrus fruits; technically a berry.
heteroblastic: Describes a plant which has adult parts distinctly different in form from the juvenile parts.
heterocarpous: Producing more than one kind of fruit.
heteroecious: Parasitic on alternating hosts; starting life on one organism, then affecting a second species.
heterogamete: Either of a pair of gametes that differ from each other in shape, size, or behavior, usually occurring as large nonmotile oogametes and small motile sperms.
heterogamous: Bearing two kinds of flowers.
heterogamy: The union of recognizably male and female gametes.
heteromallous: Turned in different directions.
heteromorphic (alt. heteromorphous): With different forms during the life-cycle; e.g., a fern with the sporophyte different in form from the gametophyte.
heterophyllous: The presence of two or more distinct leaf shapes on a single individual.
heterostyly (adj. heterostylous, adj. heterostyled): A species in which flowers are similar except that the stigmas and anthers are held at different levels relative to each other, because style length differs between plants. See also: homostylous.
heterotrophic: An organism that requires chemical energy from already formed organic molecules; dependent on organic food made by photosynthetic plants.
hexaploid: Having six sets of chromosomes.
high analysis fertilizer: A powder containing large quantities of nutrient elements.
high-centered: Having the central petals longest; the classic hybrid tea rose form.
higher taxa: Those names ranking above the species level, e.g., genus, family, order, etc.
hillock: A small hill. See also: knoll.
hilum: The scar or point of attachment of the seed.
hip: The closed and ripened receptacle of a rose which contains the seed.
hippocrepiform: Horseshoe-shaped.
hirsute: Pubescent with rather coarse or stiff hairs.
hirsutulous: Slightly hirsute.
hirtellous: Minutely hirsute.
hispid: Beset with rigid or bristly hairs or with bristles.
hispidulous: Minutely hispid.
hoary: Grayish-white with a fine close pubescence.
holocoenotic: The theory that environmental factors act as a whole or aggregate in their effect upon organisms.
holotype: One pressed herbarium specimen designated by the author as the plant on which the description and name are based. See also: isotype, lectotype, syntype, topotype, nomenclatural type, neotype.
homeopathic: Herbal medicines using the system of homeopathy founded in the 1700s. The theory is that 'like cureslike' so minute doses can cure; for example, acid will cure an ulcer.
homochlamydeous: Refers to a flower in which sepals and petals are so similar that all are called tepals.
homogamous: Able to bear just one kind of flower.
homologous: Refers to organs or parts that are similar in form or function.
homology (pl. homologies): The study of structural similarities that indicate actual physical relationships in which species with the same ancestors retain many of the same traits. See also: convergence.
homomallous: Turned in the same direction.
homomorphic: Shaped the same.
homonym: A scientific name given two or more times to plants of the same taxonomic rank but which are quite distinct from each other. See also: basionym, synonym, tautonym, autonym.
homosporous: Having spores of a single appearance and behavior.
homostyly (adj. homostylous, adj. homostyled): A species in which the flowers have stigmas and anthers held at the same level relative to each other on all plants. See also: heterostylous.
honeydew drip: The sticky mess on your car after parking under trees which have aphids or other sucking insects infesting the tree. Certain ants and fungi also feed on the honeydew.
hormone: A biochemical product of a specific cell or tissue that causes a change or activity in a cell or tissue located elsewhere in an organism.
horny: With a texture which is hard and brittle, but having a fine texture and is easy to cut.
hort.: A term used in a botanical name to indicate that it is not a properly accepted binomial, but is a name used by gardeners and nurseries, perhaps published, but in nursery catalogs rather than scientific journals. It can stand for three terms: hort., meaning "of the garden;" hortorum, meaning "of gardens;" or hortulanorum, meaning "of gardeners." All three are abbreviated hort., and are never capitalized so as to avoid being mistaken for an author's name.
hortus conclusus: An enclosed garden, as that of a monastery. in art, a representation of the Virgin and Child in a fenced garden; from the latin, "enclosed garden". See also: hortus deliciarum.
hortus deliciarum: A walled garden, like the hortus conclusus, but geared more toward the pleasure of its ownsers and more secular in its motifs; from the latin, "pleasure garden".
hortus fenestralis: A window garden; a window box in the form of a miniature greenhouse; from the latin, "window garden".
hortus siccus: A collection of dried and pressed plants, often arranged in book form; an herbarium; from the latin, "dired garden".
hose-in-hose: With one perfect corolla inside another.
hot caps: Paper or plastic tent covers used to protect small plants from damaging weather conditions.
hotbed: An outdoor pit enclosed with a glass roof and heated by fermenting material, hot water pipes, or electric cables.
houseplant: A plant which can be grown indoors, usually for decorative reasons.
ht.: Abbreviation for plant height.
humate: A salt or ester of a humic acid.
humectant: A substance which promotes retention of moisture; a moistening agent such as crystals of polymer hydrogel, which take up water, releasing it slowly for the roots of thirsty plants.
humidistat: An instrument for measuring, sometimes controlling, the amount of water vapor in the air.
humidity (adj. humid): The moisture in air.
humidor: A tightly closed container which holds a constant level of moisture in the interior, such as for long-term preservation of seeds or storage of fruits and vegetables.
hummock: A mound rising above the surrounding land, usually overgrown with vegetation.
humus (adj. humic): Partly or wholly decomposed vegetable matter.
husk: The outer layer of certain fruits like walnuts Juglans, as an outgrowth of the perianth or involucre.
hyalescent: Translucent.
hyaline: Transparent or translucent.
hydathode: An epidermal structure specialized for the secretion or exudation of water.
hydration: The reaction of cement with water to form a chemical compound.
hydraulic seeding: A method of planting grass seed by spraying it in a stream of water, which may contain other materials such as mulch or plant food.
hydric: Of, or adapted to, an extremely moist habitat.
hydromulch: The process of mixing grass seed with water and mulch for spraying onto bare soil directly.
hydrophyte (adj. hydrophytic): A plant adapted to growing in water, waterlogged soil or on a substrate that becomes inundated on a regular basis.
hydroponics: Raising plants in a totally soilless environment. Plants are grown directly in water with nutrients added as necessary, usually in a greenhouse or under artificial lights.
hydrotropism: The growth of an organism or a part, such as a root, in response to the presence of water.
hygroscopic: 1. Altering form or position through changes of moisture. 2. Readily absorbing water and thereby altered in form or direction. Hygrometric is sometimes used with a similar meaning. 3. Pertaining to water that is electrostatically bound to the surface of dirt particles and is therefore unavailable to plants.
hylea: The primeval forest.
hypanthium: A cup-like base of a flower to which the stamens, sepals and petals are attached.
hypertensive: Refers to an herbal medicine that can elevate blood pressure.
hypha (pl. hyphae): The microscopic, multicellular, nonphotosynthetic filaments of fungi and seaweeds.
hypochil: The (often fleshy or otherwise modified) basal portion of the labellum or lip in Orchidaceae.
hypocotyl: The part of the stem of an embryo or young seedling below the cotyledons.
hypocrateriform: Salverform; a tubal flower flaring out into a flat top.
hypodermis: A layer of cells immediately internal to the epidermis.
hypogeal: Of or relating to the emergence of cotyledons below the surface of the ground. See also: epigeal.
hypoglycemic: 1. Refers to herbal medicines that can lower blood sugar. 2. A patient with low blood sugar.
hypogynous: Situated on the receptacle beneath the ovary and free from it and from the calyx; having the petals and stamens so situated.
hypolimnion: The lowest layers of a body of water, below the thermocline, where water does not circulate freely.
hyponasty (adj. hyponastic): In plant physiology, the state in which more vigorous growth occurs in the lower surface of an organ, such as a young fern frond, causing an upward curvature. See also: epinasty.
hypophysis: A swelling of the seta immediately under the capsule.
hypotensive: Refers to herbal medicines that can reduce blood pressure.
hysteranthous: Refers to plants that have flowers develop before the leaves.
idioblasts: Specialized epidermal cells which produce slime or gum.
illegitimate: Refers to a name published validly, but not satisfying one or more articles of the Code of botanicalnomenclature or the Code of Nomenclature for cultivated Plants.
imbricate: Overlapping, either vertically or spirally, where the lower piece covers the base of the next higher, or laterally, as in the aestivation of a calyx or corolla, where at least one piece must be wholly external and one internal.
imbricated: Closely overlapping each other like the tiles of a roof.
immersed: 1. Covered up; when related to mosses, refers to the capsule when the perichaetial leaves project beyond it. 2. Growing wholly underwater.
immigrant: One who moves or immigrates into an area. An animal is an emigrant when leaving one area, but the same animal is an immigrant when moving into the new area.
imparipinnate: Having an uneven number of pinnae; lacking a terminal pinna. See also: paripinnate.
imperforate: Lacking holes.
impressed: Bent inward, hollowed, or furrowed as if by pressure.
in vitro: Outside the living body and in an artificial environment, as a tissue culture.
incised: Cut sharply and irregularly, more or less deeply.
included: Not at all protruded from the surrounding envelope.
incompatible: Refers to plants that will not form a lasting union at a graft.
incomplete flower: Lacking one or more whorls, i.e., sepals, petals, stamens, or carpels, of the complete flower.
incrassate: Thickened, often relating to cell walls.
incumbent: Describes cotyledons lying with the back of one against the radicle.
indefinite: Inconstant in number or very numerous.
indigenous: Native and original to the region.
indumentum: A massing of fine hairs, glands, or prickles.
induplicate: Having edges or margins folded inward.
indusiate: Bearing indusia.
indusium (pl. indusia): The thin, scale-like covering of immature sori.
industate: Provided with an indusium.
inerm (alt. inermous): Unarmed, no prickles, thorns, teeth, etc.
inferior ovary: With the flower parts growing from above the ovary; one that is adnate to the calyx.
inflated: Bladdery; applied to the alar cells of leaves when enlarged much beyond the size of the neighboring cells.
inflexed: Bent inwards.
inflorescence: The flowering part of a plant, and especially the mode of its arrangement.
influent: 1. An organism which sways interactions within a community but is not a dominant species; one which influences. 2. The flow of water from a stream into a body of water, especially subterranean storage. See also: effluent.
infra-: As a prefix, denotes below.
infrageneric: Refers to any taxon of a rank below that of genus, such as species, variety, cultivar, etc.
inframedial: Below the middle.
infraspecific: A taxonomic group within a species, such as a subspecies.
infructescence: The grouping or arrangement of fruits borne on a plant.
infundibuliform (syn. infundibular): Shaped like a funnel.
inoculant (syn. inoculum): The material used in an inoculation.
inorganic: 1. Being or composed of matter other than that from a plant or animal. 2. Not arising from natural growth; artificial.
inorganic fertilizer: A powdered or liquid chemical mix of nutrients which does not contain carbon.
insect vectors: Bugs that carry and distribute disease-causing microorganisms.
insectivorous (n. insectivore): Feeding on insects.
inserted: Attached to or growing out of.
integrated pest management (abr. IPM): A philosophy of pest management based on the idea of using the least dangerous course first; stresses the use of natural controls, such as insect predators, over the use of chemical pesticides.
integument: An outer covering or coat.
inter-: As a prefix, denotes between or among.
intercalary: Of a meristem situated between the apex and the base.
intercalary growth: Growth in the tissue between the apex and the base.
intercalary inflorescence: An inflorescence that either arises in an internodal position, or one originally terminal but ceasing to be so when vegetative growth subsequently resumes from the stem apex.
interfoliaceous: Between the leaves of a pair, as the stipules of many Rubiaceae.
intermediate: 1. Refers to a grafting scion which is attached at both ends either simultaneously or successively. 2. Refers to hybrids apparently combining the characters of both of their parents in equal measure and standing midway between them.
internode: The portion of a stem between two nodes.
interpetiolar: Describes a stipule located between the petioles of two opposite leaves. See also: intrapetiolar.
interrupted: Describes an inflorescence with the flowers unevenly distributed along the axis, with conspicuous gaps. Also describes the fertile frond of some ferns with the clusters of sporangia similarly arranged.
interspecific: Refers to hybrids between two separate species of the same genus.
interstaminal corona: The fleshy lobes, often connate into a tube, attached to the base of the staminal column in the interstaminal areas of members of the family Asclepiadaceae. See also: gynostegial corona.
intertidal: The shore zone between high and low tides.
intra-: As a prefix, denotes within or inside.
intramarginal: Within and near the margin.
intrapetiolar: Describes a stipule located between a petiole and the stem. See also: interpetiolar.
intricate: Tangled.
introduced: Brought intentionally from another region for purposes of cultivation.
introgression: The formation of a range of intermediate plants by hybridization among parents and progeny.
introrse: Turned inward or toward the axis.
invaginated: Inside a sheath.
invalid: Refers to scientific names published with incomplete information or in an invalid publication.
invasive: Spreading aggressively from the original site of planting.
involucel: A secondary involucre, as that of an umbellet in Umbelliferae.
involucellate: Having an involucre.
involucral: Belonging to an involucre.
involucrate: Having an involucre.
involucre: A circle or collection of bracts surrounding a flower cluster or head, or a single flower.
involute: 1. Rolled inward. 2. With margins of ray florets rolled forward along their longitudinal axis. When fully involute, the margins touch or overlap so only the reverse of the floret is visible.
iron chelate (alt. chelated iron): A powdered compound used as a soil additive to boost the amount of iron available to plants.
irregular: 1. Varying in form. 2. Asymmetrical.
irregular flower: Describes a flower showing inequality in the size, form, or union of its similar parts.
irrigation: The provision of water to plants to supplement rainfall. See also: drip irrigation, center pivot irrigation.
isidia: Finger-like outgrowths from the upper cortex of a lichen.
isodiametric: Having equal diameters.
isogamy: The union of equal gamete.
isolateral: Having upper and lower surfaces which are similar in form.
isomorphic: Having a similar form, but being genetically different.
iteroparity: Refers to an organism that has multiple reproductive seasons over its lifetime. See also: semelparity.
jointed: 1. With nodes on the stem. 2. Having obvious, thickened areas between cells.
jugate: Paired, with prefixes for the number of pairs; bijugate would be two pairs.
jugum: A pair.
julaceous: Smooth, slender, and cylindric; like a catkin or a worm.
junceous: Rush-like.
juvenile: Young; not adult.
karyoevolution: Changes in the chromosome set of a number or structure occurring through evolutionary change.
karyotype: Characterization of the chromosome set of an individual or group, described in terms of number, length, centromere position, etc.
katabolism: The process of breaking down protoplasm with the liberation of energy and the formation of simplesubstances.
kelp: Any of various large brown seaweeds, sometimes used to enrich poor soil.
kernel: The nucleus of an ovule or seed; everything inside the coat.
kingdom: One of the primary taxonomic categories into which natural objects are commonly classified. There are currently five kindoms used: Plantae, Animalia, fungi, Monera (bacteria) and Protista (protozoans, some types of algae, etc.).
kitchen garden: A garden where vegetables, fruits, and herbs are grown for use in cooking.
knees: When growing in a swamp, the above-water spongy roots of cypress, Taxodium. These provide air to the interior systems of the tree.
knot garden: An elaborately designed garden consisting of flowers, herbs, and/or low shrubs arranged in intricate, geometric, knot-like patterns when seen from above.
knotted: Having nodes or lumps.
krummholz (syn. elfin forest): Scrubby, dwarfish growth of trees, often forming a distinctive zone at the tree line of mountains.
kwongan: The sclerophyllous vegetation of the sand plains of south-western Western Australia.
labiate: Lipped; belonging to the Labiatae.
labriform: Lip-shaped.
labyrinthiform: With complicated sinuous lines or winding passages.
lacecap: A flattop inflorescence in which the outer flowers are larger than the inner ones, and the outer are sterile.
lacerate: Irregularly cleft as if torn.
lachrymiform (alt. lacrymiform): Tear-shaped.
laciniate: Slashed; divided into narrow pointed lobes.
laciniated: Describing dahlias with the split or fimbriation in proportion to ray floret length, and no less than 1/6 of ray floret length, there should be a twisting in the area of the split involute or revolute ray florets, to give an overall fringed effect.
lactifer (alt. lacticifer): A latex duct which may or may not produce the milky sap.
lactiferous (alt. lacticiferous): Describes a plant with a milky sap; producing latex.
lacuna: A cavity or gap, usually referring to one found in tissue.
lacunose: Pitted.
lacustrine: Refers to, produced by, or formed in a lake. Lacustrine wetlands are those reaching into a lake and acted on by waves and currents.
laevigate: Smooth, polished.
lageniform: Shaped like a bottle or flask.
lagoon: A relatively shallow pond, sound or lake, especially one connected to the sea.
lake plain: The nearly flat bed of an extinct lake or the lowland surrounding an existing lake.
lake senescence: The aging process of a wetland or lake that results from excess sediment and vegetation.
lamella (pl. lamellae): 1. A thin flat plate or laterally flattened ridge. 2. The acid crystals of lichens shaped in this way.
lamellate (alt. lamellose): Composed of or arranged in layers or thin plates; having lamellae.
lamina: A blade; the leafy portion of a frond.
laminal: Superficial on the surface of thalli or lobes of lichens.
lanate (alt. lanose): Woolly.
lance-shaped: Elongate in shape, broadest below the middle and gradually rowed toward the tip.
lanceolate: Shaped like a lance-head, several times longer than wide, broadest above the base and narrowed to the apex.
landlocked property: A parcel of real estate which does not border any road for access.
landraces: Crop cultivars or animal breeds that evolved with, and has been genetically improved by, traditional agriculturalists, but has not been introduced in modern breeding practices.
landscape architect: A person trained in the location of landscape elements for human use and enjoyment. It involves the placement of structures, traffic flow, and plantings.
landscape architecture: The design of outdoor space for maximum enjoyment.
landscape contractor: A company or individual performing landscape installations.
landscaper: An improper term applied to anyone doing landscape work. Often the person is untrained.
language of flowers (alt. symbolism of flowers): A complex code under which each species of flower, even individual colors of that species, carries a meaning or message.
lanose (alt. lanate): Woolly.
lanuginose: Nearly lanate, but with shorter hair.
lasion: A periphyton in which the organisms are densely populated and are interdependent. See also: epiphyton.
lateral: Side shoot, bud, etc.
lateral cane: Any cane growing from a main cane.
lath: In gardening, any overhead plant protection structure that reduces direct sunlight or protects plants from frost. Wooden strips called laths, wired together in snow fences, were originally used for that purpose.
latiseptate: Having broad partitions. See also: angustiseptate.
latrorse: Turned sideways.
lawn: An area of cultivated and mown grass.
lawn mower: A lawn mower is a machine utilizing one or more revolving blades to cut a grass surface to an even height. Most common types are the reel mower, walk-behind mower, ride-on tractor and zero turn mower.
leader: The highest terminal shoot of a plant.
leaf: A usually flat, green structure of a plant where photosynthesis and transpiration take place and attached to a stem or branch.
leaf axil: The angle between a petiole and the stem.
leaf blight: Any of various diseases which lead to the browning and dropping of a plant’s leaves.
leaf bud: A bud which contains undeveloped leaves.
leaf curl: A disease that causes leaves to roll up.
leaf gap: A break in a stem's vascular tissue above the leaf trace.
leaf litter: The leaves that have fallen from a plant, either through normal seasonal changes or due to disease. Especially in the latter case, leaf litter can harbor pathogens and should be cleaned up promptly, particularly around plants such as roses. In a naturalized, woodland setting, leaf litter can be a normal part of the workings of the garden.
leaf miners: Tiny grubs that tunnel in leaves leaving whitish blotches or trails.
leaf mold: A form of humus composed of decayed leaves, often used to enrich soil.
leaf primordium: A lateral outgrowth from the apical meristem that develops into a leaf.
leaf scar: The mark left on the twig at the point of attachment of a leafstalk when the leaf falls.
leaf spot: Any of various plant diseases that cause well-defined areas of tissue to die creating noticeable spots.
leaf trace: The strand of vascular tissue between the vascular bundle of the stem and the leaf.
leaflet: A single division of a compound leaf.
leathery: Of a smoothly tough texture.
lectotype: A specimen selected from the original material used by the author in naming a taxon, when no holotypewas designated or if the holotype is missing. See also: holotype, isotype, nomenclatural type, syntype, topotype, neotype.
lee shore (alt. leeshore): The shore toward which the prevailing winds are blowing. It is not protected from strong wave action and may have breakers. See also: windward shore.
leeward: The side opposite that from which the wind blows, the sheltered side. See also: windward.
leggy: Refers to a plant growing tall and spindly, usually from inadequate sunlight.
legume: The dry, single-celled fruit of the Leguminosae, formed of a simple pistil, and usually dehiscent by both sutures and often grouped in a long pod, as found in a pea-pod.
leguminous: Pertains to a legume or to the Leguminosae.
lenticular: Lentil-shaped; of the shape of a double-convex lens.
lentiginous: With very tiny dots, as though covered with dust.
lepidote: Beset with small scurfy scales. See also: leprous.
leprous: Scurfy, covered with tiny scales. See also: lepidote.
leptocaul: With a thin primary stem.
leptodermous: Thin-coated; applied to capsules when soft and pliable.
leptosporangiate: Describes a fern with sporangia having walls only one cell thick. See also: eusporangiate.
leptosporangium: A thin-walled sporangium originating from a single epidermal cell.
leucoplast: A colorless plastid in the cytoplasm of interior plant tissues that is potentially capable of developing into a chloroplast.
liana (alt. liane): Any of various high-climbing woody plants, usually found in the tropics.
lianoid: Vine-like.
lichen: An organism formed by the symbiotic association of an alga and a fungus.
life form: Characteristic structure of a plant or animal.
lifting: Digging up and removing a plant from its surrounding soil.
light frost: A frost where the air has dropped below freezing but the ground has not. Many plants can survive a light frost but cannot survive a hard frost.
light shade: 1. Incomplete shade, where some sunlight is still available. 2. An area in shade for only part of the day.
lignin: The chief noncarbohydrate constituent of wood, a polymer that functions as a natural binder and support for the cellulose fibers of woody plants.
lignotuber: A woody swelling on the trunk of a tree or shrub, below or just above the ground, that contains adventitious buds from which new shoots develop if the top of the plant is cut or burnt.
lignum vitae: The very hard, heavy wood of any of several trees of the genus Guaiacum.
ligulate: Furnished with a ligule.
ligule: A strap-shaped corolla, as found in the rayflowers of Compositae. 2. A thin often scarious projection from the summit of the sheath in grasses.
limb: 1. A branch of a tree. 2. The expanded portion of any petal, or of a leaf, such as the expanded portion of a gamopetalous corolla above the throat. 3. The upper part of a leaf as distinct from the leaf base.
limbate: Describes a leaf bordered by a part of another color.
limbed: Refers to timber with branches removed.
lime-dots: White salt concretions around a hydathode.
lime-hater: Plant unable to thrive in alkaline.
limnology: The study of fresh water bodies with regard to physical, chemical, geological, meteorological, biological, and ecological conditions. Oceanography encompasses the same specialties for marine salt waters.
line-out: To set out young rooted plants in the outdoor nursery to grow larger or on which to work grafts.
linguiform: Tongue shaped.
Linnaean (alt. Linnean): Of, or relating to, the Swedish botanist Carolus Linnaeus (1707-1778), or the taxonomic classificationsystem of binomial nomenclature he originated.
lip: Each of the upper and lower divisions of a bilabiate corolla or calyx; the peculiar upper (but by a twist of the pedicel apparently lower) petal in orchids.
lip petal: The lower petals of some irregular flowers, often elaborately showy, as in orchids.
lister: An agricultural implement consisting of a double plow, in which the plowshares force the soil in opposite directions, forming a series of alternate ridges and furrows. The basin lister comes with an attachment that forms low soil dams across each furrow at intervals of 15 to 25 feet (to 6.5 m.), forming basins to hold large amounts of water.
literature retrieval: The process of selecting--manually or automated--appropriate documents within the mass of published literature that are of interest to the user. See also: document retrieval, data retrieval.
lithic context (syn. stratigraphic context): The rock layers surrounding a fossil that allow the age of the fossil to be determined.
lithophyte: A plant that grows on rocks.
littoral: Of or existing on a shore.
littoral drift: Sediment and detritus moved along the shore by waves and currents. See also: littoral zone.
littoral zone: The shallow water along the shore from zero to the depth where plants no longer root, about 10 feet (3 m.) deep.
liverwort: A nonflowering plant in the botanical class Hepaticae, closely related to the mosses.
loam (syn. loamy soil): 1. A generally fertile and well-drained soil, containing clay, sand, and a significant amount of decomposed organic matter. 2. Any soil.
lobate: Having numerous lobes.
lobe: Any segment of an organ, especially if rounded.
lobedleaf: A leaf whose margin is shallowly divided.
lobulate: With irregular, rounded lobes.
location survey: A less expensive land survey done to only prove that a specific building or right of way is situated on a plot of land, rather than the more detailed metes and bounds survey which gives all border limitations and positions.
lociation: A variation of a climax association, differing from the normal in the kinds of subdominants. See also: faciation.
loculicidal: Longitudinally dehiscent between the partitions of the locule, as in Liliaceae. See also: septicidal.
locus (pl. loci): The position in a chromosome of a particular gene or allele.
lodicule: One of a pair of tiny scales at the base of a grass floret, believed to a be reduced perianth segments.
loess: A deposit of relatively consistent fine soil, mostly silt, usually carried by wind.
log lifter: A tool designed to easily roll a log, a cant hook, or pike.
loment: On legumes, a pod which narrows between the seeds, drying and splitting apart at maturity into one-seeded segments.
lomentum: A pod constricted between the seeds.
long-day: Of, relating to, or being a plant which flowers only after being exposed to daylight for periods longer than a particular length, usually in the late spring or early summer.
long-lived: Describes a plant where the individuals subsist for a number of years.
longitudinal: Lengthwise.
loppers (alt. lopping shears): Long-handled pruning shears for cutting larger branches; may be rachet tools, with telescoping handles or specialized long reach type.
lorate: Strap-shaped.
lotic: Of, relating to, or living in actively moving water. See also: lentic.
luculicidal: Dehiscent into the cavity at a cell through the dorsal suture.
lumen (pl. lumina): The central cavity of an organ or cell.
lunate (alt. lunulate): Of the shape of a half-moon or crescent.
lustrotts: Glossy.
lutein (syn. xanthophyll): A yellow carotenoid pigment, usually found with chlorophyll in plants. Also called xanthophyll.
lyrate: Pinnatifid with a large and rounded terminal lobe and with the lower lobes small.
machete: A large powerful knife used to clear brush, e.g., trails through jungle areas.
macrophytes: All visible plants in any habitat, not microscopic bacteria or algae.
macrosporangium: The receptacle in which macrospores are developed.
macrospore: The larger kind of spore in Selaginellaceae, etc.
maculate: Blotched with broad, irregular patches of color.
main shoot: A basal cane or a strong lateral cane.
male cone: The conical, pollen-bearing male element of a conifer.
mallee: A growth form in which several stems arise from a lignotuber.
malpighiaceous hairs: Hairs which are straight and oppressed but attached by the middle.
mamillate (syn. mammillar): Convex with a short projection in the center.
mammillate (alt. mammillated): Shaped like a nipple.
manila coin envelopes: Small easily labeled containers for otherwise easily lost parts of plant specimens such as seeds, individual flowers, leaves, etc.
manure: Animal dung used as a fertilizer.
marcescent: Withering but persistent.
marginal rays: Fully developed ray florets which establish and determine the maximum diameter of a flower, as distinguished from the immature central rays (used in describing dahlias.)
marginate: With a border of a different color.
maritime: Describes climate mainly influenced by the sea, generally with mild winters, cool summers, and frequent rain.
marl: A mixture of clay and the carbonates of calcium and magnesium, from precipitation in acidic waters, and from dissolved shells and limestone.
massula (pl. massulae): Structures associated with megaspores or enclosing and trapping microspores to increase the likelihood of fertilization.
matted: Formed into a mat.
mattock: A waist-high tool with a metal head consisting of a horizontal blade with one end twisted as a dull axeand the other end flat or pointed. It is used for breaking hard soil, digging roots, and other heavy work.
maze (syn. maze garden): A confusing intricate network of passages, particularly one created with tall, dense hedges forming the walls and separating the pathways.
meadow: Typically, a level grassland or field within a larger ecosystem, such as a forest. Often, the grass grown on its natural, low-lying, moist areas is used for forage or fodder or cut for hay.
mealy: Farinose.
mealybug: Any of the scale insect belonging to the family Pseudococcidae that have a white powdery covering and are destructive plant pests, particularly toward fruit trees.
median: Refers to the central crosswise area of a leaf, as 'median width' would be the broadest width at midpoint.
median leaf-cells: Cells from the middle of the leaf.
medicinal herb: Any herb which is used as a curative or preventative.
medifixed: Attached by or at the middle.
medulla: 1. The central tissue of a structure, generally referring to the pith. 2. The inner part of the thallus of a lichen.
medullary: Made up of pith, spongy.
megasporangium (pl. megasporangia): The female sporangium containing the megaspores.
megasporophyll: The leaf bearing the megasporangia.
meiosis: Cell division; the nuclear division that halves the chromosome number.
meiotanglum: The sporangium or gametangium in which meiosis occurs.
mellitophily: Pollination by bees.
membranaceous (syn. membranous): Like a membrane; thin, rather soft, and more or less translucent.
membranous (alt. membraneous, alt. membranaceous): Thin in texture, soft and pliable.
meniscoidal: Thin and concavo-convex, like the crystal of a watch.
mentum: A chin-like extension on a flower, particularly in Orchidaceae.
mericarp: One of the achene-like carpels of Umbelliferae.
meristem cloning (n. mericlone): Artificial propagation of a plant using cells taken from the meristem of a parent plant and yielding genetically identical offspring.
Merrill cases: Cardboard containers purchased flat for easy transport, then opened in the field when needed to hold plant specimens.
mesic: Of, or adapted to, a temperate, moderately moist habitat; neither xeric nor hydric.
mesocarp: The fleshy, middle portion of the wall of a succulent fruit between the skin and the stony layer.
mesophyll: The middle and photosynthetic tissue of a leaf.
mesophyte: Dryland plants, xerophytes, have adaptations to survive for months with no water; water plants, hydrophytes, live in water; mesophytes are all other plants--which need small amounts of water on a regular basis.
mesosperm: The middle layer of the coat of a seed.
metaxylem: The primary xylem formed after the protoxyle.
metes and bounds: A surveyor's term meaning the legal circumscribing lines setting the outer limits of a tract of land.
microclimate: Climate specific to a small area; may var. significantly from that of surrounding areas.
microconidia: Bacilliform cells produced in pycnidia.
microenvironment: The environment of a very small area.
microevolution: Evolution as a result of very small genetic variations, which may cause the formation of a new subspecies.
microfossil: A microscopic fossil, e.g., that of a pollen grain.
microgametophyte: The male gametophyte, formed by vegetative growth of the microspore of a heterosporous plant.
microhabitat: A very small habitat, such as a rock crevice or a clump of grass.
micronutrient: An organic compound, such as a vitamin, essential in minute amounts to the growth and health of a living organism.
microphyll: A very small leaf.
micropropagation: Propagation of plants through tissue cultures.
micropyle (adj. micropylar): 1. A minute opening on the ovule through which the pollen tube usually enters. 2. The point upon the seed at which was the orifice of the ovule.
microsporangium (pl. microsporangia): The male sporangium in which microspores are developed.
microsporophyll: The leaf bearing the microsporangi.
midrib: The central or main rib of a leaf.
midvein: The principal vein in the blade of leaf, pinnule, or segment.
mildew: A fungus that leaves a thin white coating on the surface where it grows.
mimosiform (alt. mimosoid): With round or conical flower heads having inconspicuous sepals and petals but conspicuous stamens, as found in the genus Mimosa.
ming: A dwarfed evergreen conifer grown as bonsai.
minimum viable population: The isolated population of least numbers which has a good chance of surviving despite the foreseeable effects of demographic, environmental, and genetic events and natural catastrophes.
misapplied: Refers to the usage of a taxon name for an incorrect plant; such names are homonyms and also synonyms of the plants to which they truly describe.
mitochondrion (pl. mitochondria, syn. chondriosome): Cytoplasmic structure containing enzymes used in converting food to energy.
mitosis: Cell division in which the number of chromosomes in the daughter cells is the same as that of the parent cell. See also: meiosis.
mitriform: Shaped like a mitre or cap.
moat: A ditch filled with water and usually acting as a barrier.
moniliform: Resembling a string of beads; cylindrical with contractions at intervals.
mono-: A prefix meaning one.
monocarpellary: Refers to fruit with one female organ.
monocarpic: Describes a plant that dies after flowering just once.
monocephallic (alt. monocephalous): Bearing a single flower head.
monocephallous: Having a single flower head.
monochasial cyme: Like a dichasial cyme, but with branches on only one side.
monochasium (pl. monochasia, adj. monochasial): A cyme with a single flower on each axis of the inflorescence.
monochlamydeous: Describes a flower which has a single whorl of perianth parts.
monoclinous (alt. monoclinus): Having pistils and stamens in the same flower.
monocolpate: Refers to pollen grains with a single furrow.
monocotyledon (alt. monocot, adj. monocotyledonous): A plant with one cotyledon or seed leaf.
monoculture: The agricultural practice of planting a field or other land mass with a single crop, all of the same age, like wheat or pine trees. Single crop planting often leads to increased infestation by disease or insects.
monoecious (alt. monoicous): Having stamens and pistils in separate flowers on the same plant.
monoembryonic: Refers to seeds or ovules with a single germ cell or embryo.
monogeneric: Refers to a family or taxon of higher rank made up of a single genus.
monolete: Describes spores having a single, unbranched scar.
monomial: The single word designation such as genus Iris, or family Iridaceae. See also: binomial.
monopetalous: In the strictest sense, refers to a flower with a single petal; however, it is often used to refer to gamopetalous flowers in which several petals are united to form a tube.
monophyletic: Descended from a single ancestral line. See also: polyphyletic.
monoploid: Having a single set of chromosomes.
monopodium (pl. monopodia, adj. monopodial): The main axis of a stem or rhizome maintaining a single direction of growth and giving off lateralbranches or stems. See also: sympodium.
monospecific: Refers to a genus which has a single species.
monotypic: A taxonomic division that has only one subdivision, as a family containing only one genus, or a genus with a single species.
montane: Of, growing in, or inhabiting mountain areas.
morphocline: A graded series of character states of a homologous character.
morphology: The study of the form and structure of an organism.
moss: A small nonflowering plant of the class Musci.
mother bulb: A mature bulb which has produced small offset bulbs.
mother plant: 1. A mature plant from which cuttings are taken. 2. The female ancestor of a hybrid.
mother-cell: The cell that gives rise to a particular structure or particular reproductive units.
motile: Actively moving or capable of moving spontaneously.
mottled: With variegated coloring.
mound layering: A method of propagation whereby a branch or stem is scored and then brought into contact with the soil to spur rooting.
moxa: A Chinese herbal process of burning dried herbs on or above the skin to stimulate an acupuncture point or serve as a counterirritant.
mucilage (adj. mucilaginous): A viscous, slimy material exuded by certain plants.
mucous: Slimy; viscous.
mucro: A short and small abrupt tip.
mucronate: Refers to a leaf or other organ ending suddenly with a stiff spine as a continuation of the midrib; tipped with a mucro.
mucronulate: Diminutive of a mucronate, with a small spine.
mud flats: The bare level bottoms of bodies of water exposed by a drop in the water level. A mud bar may be exposed in a constant water level by a buildup of sediments.
mud logger (mud logging): A person who works with geologists, lubricating the cutters of cores, and analyzing the resulting rock fragments for stratigraphy, keeping a record or log of the results.
muddled center: A flower center with petals that are disorganized, not forming a pattern. A term applied to Old Garden Roses.
mulch: An organic or inorganic soil covering, used to maintain soil temperature and moisture and to discourage the growth of weeds.
multi-: A prefix meaning many.
multicellular: Formed of two or more cells.
multicipital: Many-headed.
multifid: Cleft into many lobes or segments.
multigeneric: Refers to hybrids with more than two generations in their ancestry, e.g., x Potinara (Brassavola x Cattleya x Laelia x Sophronitis).
multiline: A term used by nurseries to indicate that a horticultural variety derives from several closely related lines.
multiplanar: Describes divided leaves, with the lobes held in several to many planes.
multiple fruit: One in which the carpels of several flowers join in a single fruit, like a fig, Ficus. This differs from an aggregate fruit which derives from the multiple carpels of a single flower, e.g., a raspberry, Rubus.
multiseptate: Bearing more than two septae.
muricate: With a rough surface composed of many short, hard points.
muriculate: Very finely muricate.
muriform: Divided into many chambers.
muscariform: Shaped like a broom.
mutant: 1. An individual produced with sudden and marked differences from the parent, and with a new genetic pattern. 2. A sport.
muticous: Not pointed.
mutualism: A type of symbiosis in which both members depend on each other for their nutrients or other services.
mycelium (pl. mycelia): The mass of interwoven filamentous hyphae that forms especially the vegetative portion of the thallusof a fungus.
mycology: The study of mushrooms and other fungi.
mycorrhizal: A term describing plants which have a symbiotic relationship with the mycelium of a certain fungus.
myrmecophilous: Strictly, ant-loving; refers to plants which have symbiotic relationships with ants.
myrmecophyte: A plant in symbiosis with ants.
named cultivar: A cultivar that has been given a recognized horticultural name.
napiform root: A taproot which is broader than it is long, like a turnip.
narcotic: A drug used to relieve pain and induce sleep.
native plant: A plant occurring naturally in an area and not introduced by man; indigenous.
natural layering: The spontaneous rooting of stems when they make contact with the soil.
naturalize (alt. naturalise): 1. To cause a plant to become established and grow undisturbed as if native. 2. The establishment of exotic species in the wild that can reproduce without human intervention.
navicular: Boat-shaped.
nec: In nomenclature, this is placed between the names of two authors, indicating that neither named the taxon in a valid manner.
neck: The lowest part of the capsule just above the point where it joins the seta.
necrosis: The localized death of living tissue usually caused by a pathogen.
nectariferous: Producing nectar.
nectarivore: An animal, including insects and bats, that eats nectar.
nectary: Any place or organ where nectar is secreted.
needle: The very long and narrow leaf of pines and related trees.
needle-like: Very long, narrow, and pointed at the tip.
nematode: Any of several unsegmented, elongated cylindrical worms of the phylum Nematoda. They may be parasitic in animals or plants, or free-living in soil or water. As parasites, they can cause damage to and even kill plants. Others can be benficial.
neotenic: Refers to retaining juvenile characteristics throughout the life span.
neoteny: The process of fulfilling a function in an imperfect or young state.
neotype: A specimen selected to serve as the nomenclatural type when the material used to base the name of the taxon is missing. See also: holotype, lectotype, nomenclatural type, syntype, topotype, isotype.
nervine: An herbal medicine with a soothing and mildly sedative action.
nest-fronds: Specialized, shield-shaped, basal fronds in some ferns which accumulate leaf litter forming a nest-like covering.
net-veined: With a network of veins.
neuter (syn. neutral): Without stamens or pistils.
neutral soil: Soil having a pH of 7 and therefore neither acidic nor alkaline.
neve: Granular compacted snow at the head of a glacier, or similar snow elsewhere. See also: firn.
niche: 1. Ecological niche--the role of a plant or animal in the environment, its relationship to all the living and nonliving things around it, e.g., a bat is the nighttime hunter of airborne insects. 2. Habitat niche--the specific part or smallest segment of a habitat occupied by an organism, e.g., a pillbug lives under moist rocks or detritus. See also: biotope.
nigrescent: Turning black.
nitrification: The oxidation, as by bacteria, of ammonium to nitrites and the further oxidation of nitrites to nitrates.
nitrogen carrier: A material such as a commercial fertilizer that contains the essential mineral nitrogen.
nitrogen fixation: The conversion of atmospheric nitrogen into an organic form usable by plants and other organisms. This can be through the agency of soil microorganisms, particularly rhizobia living in nodules on the roots of legumes, or by industrial methods.
nocturnal: Active only at night; flowering only at night.
nodose: Knotty or knobby.
nomen (pl. nomina): Literally, "name", particularly a scientific name assigned according to the Codes of Nomenclature.
nomen ambigua (abr. nom. ambig., alt. nomina ambigua): A name that has long referred to different taxa and should be abandoned.
nomen confusum (abr. nom. confus., alt. nomina confusa): A name based on a type, the herbarium specimens later proving to be two or more taxa.
nomen conservandum (abr. nom. cons., alt. nomina conseranda): A taxon name that has been formally accepted under the International Code for botanicalnomenclature as the correct name contrary to the usual principles of botanical nomenclature.
nomen illegitimum (abr. nom. illegit.): A name that was validly published, but contravenes the International Code for botanical nomenclature; A name which was superfluous or had already been applied to another plant.
nomen novum (abr. nom. nov.): A name proposed to replace a name which has been rejected.
nomen nudum (abr. nom. nud., alt. nomina nuda): Literally, "a naked name". Used in nomenclature to refer to the fact that the name was published without a description or diagnosis and is therefore not acceptable under the International Code for botanical Nomenclature.
nomen rejiciendum (abr. nom. rejic., alt. nomina rejicienda): Literally, "a name to be rejected". Used in nomenclature when a decision has been made to conserve an older name and the newer one is rejected. See also: nomen conservandum.
nomenclatural synonym: Any one of two or more different names based on the same plant specimen.
nomenclature: A system or set of terms or symbols; the system of providing taxonomic names for organisms.
non: In nomenclature, it means 'not' as in "Artemisia lanata Willd. non Lam."---when Willdenow in 1823 gave a new plant the same name that Lamarmarck had used in 1783 for a different plant.
nongovernmental organization (abr. NGO): A nonprofit group or association organized outside of institutionalized political structures to gain particular social objectives such as environmental protection.
nonvascular: Refers to organisms with no tissues or vessels to carry water, minerals, etc., such as mosses, fungi, algae, lichens, etc.
nostoc: A blue-green alga with filaments formed of chains of cells.
notch: A v-shaped indentation.
nothomorph: A term used in taxonomy to designate different hybrid forms derived from the same parent species, ranking essentially as a variety.
novirame: A flowering--later fruiting--shoot arising from a primocane.
noxious weeds: Plants which may cause harm to collectors, such as poison ivy, Toxicodendron radicans; or invasiveexotics or parasites and their host plants which may harm the ecosystem or agriculture of an area. See also: quarantine.
nucellus (adj. nucellar): The central body of the ovule that encloses the female gametophyte; equivalent to the megasporangium.
nucleolus: A special body in the nucleus.
nucleus (pl. nuclei): 1. The germ cell of the ovule, which by fertilization becomes the seed; the kernel of a seed. 2. The part of the protoplasm that contains the chromosomes.
nullipores: Calcareous red seaweed.
nurse grass: A fast-growing temporary grass included in most grass seed mixtures to give rapid coverage and protect permanent grasses from soil erosion, sunscald, etc.
nurse tree: A fast-growing tree planted with, or left in place near, a slow-growing, permanent tree in order to provide shade and wind protection for the permanent tree until it has reached useful size.
nut: A dry, hard indehiscent 1-celled and 1-seeded fruit, though usually resulting from a compound ovary.
nutant: Nodding, usually referring to the entire inflorescence rather than a single flower; cernuous.
nutlet: One of several small, nut-like parts of a compound fruit; a diminutive nut.
o.c.: On center; refers to the spacing on landscape plans of materials to be planted.
ob-: A prefix meaning inverted, e.g., obcordate describes a heart-shaped leaf attached at the point rather than at the cleft.
obcompressed: Compressed dorso-ventrally instead of laterally.
obconically: Inversely conical, having the attachment at the apex.
obcordate: Inverted and heart-shaped; e.g., a heart-shaped leaf with the pointed end toward the stem.
obcuneate: Like cuneate, but with the point of attachment at the broad end.
obelisk: An upright four-sided usually monolithic pillar that gradually tapers as it rises and terminates in a pyramid, often inscribed with words or designs.
obhastate: Like hastate, but with the triangular lobes at the tip.
oblanceolate: Lanceolate with the broadest part toward the apex.
oblate: Shaped like a sphere which is depressed at the poles.
obligate: Incapable of surviving without a host, as occurs with certain parasites. See also: facultative.
oblique: Unequal-sided or slanting.
obloid: Having an oblong shape but with the cross section circular and the ends rounded.
oblong: Longer than broad and with nearly parallel sides.
obovate: Inverted ovate; egg-shaped, with the broadest part above, or away from the stem.
obovoid: Having the form of an inverted egg.
obpyramidal: Shallowly triangular with the attachment at the point rather than the middle of the flat side.
obpyriform: Inversely pear-shaped, with the attachment at the narrow end; turbinate.
obscure: Hidden.
obsolescent: Becoming rudimentary; refers to an organ no longer functional and reduced to vestigial remains.
obsolete: Not evident; rudimentary.
obtuse: Blunt or rounded at the end.
ocellated: Having spots.
ochrea: The sheath around the base of the seta, terminating the vaginula.
ochroleucous: Yellowish-white.
ocrea (alt. ochrea): A legging-shaped or tubular stipule.
octoploid: Having eight sets of chromosomes.
odd pinnate: A pinnate leaf with a terminal leaflet, hence having an odd number of leaflets.
odoriferous: Producing an odor, often fragrant.
officinal: Of the shops; a plant used in medicine or the arts.
offset: A short sideshoot arising from the base of a plant; also a small bulb arising from the base of another bulb.
offshore wind: Blowing from the land across the water, usually warmer than an onshore wind, and with lower waves.
Old Garden Rose (abr. OGR, syn. Old English Rose): A hybrid rose which has been in cultivation since before 1867.
oleaginous: Refers to fleshy, oily tissue.
oligo-: A prefix denoting few, as oligopetalous means with few petals.
once-compound: A compound leaf with a single set of undivided leaflets.
onshore wind: Blowing from the water to the shore, building large waves as it uses its full fetch. This is usually cooler than an offshore wind.
ontogeny: The course of development of a single organism.
oocyte: A cell from which an egg develops.
oogamy: Conjugation between sperms and egg.
oogonium: The organ producing the egg or eggs.
ooshere: The egg cell or ovum found in the base of the archegonium.
oospore: The fertilized nucleus or germ-cell of the archegonium in cryptogams, from which the new plant is directly developed.
opaque: Dull; neither shining nor translucent.
open pollination: Pollination by natural mechanisms such as insects, wind, etc., as opposed to selective pollination by a plant breeder.
operculate: Furnished with a lid.
operculum: A lid; the upper portion of a circumscissile capsule, which on detachment permits the spores to escape.
opposite: Describes leaves arranged along a twig or shoot in pairs, opposite each other at a single point along an axis.
orangery: A many-windowed building used to house potted orange trees during winter.
orbicular: Circular.
orbiculate: Circular in outline.
orchard: A planting of fruit or nut trees.
order (alt. ordo): A category of taxonomic classification ranking above the family and below the class.
organelle: A membrane-bound body analogous to an organ and found in the cytoplasm of the cell that performs specific cellular functions.
organic: Derived naturally, from living or once-living matter.
ornamental: A plant that is grown for visual display.
ornamental plants: Ornamental plants are plants that are kept, grown and used for display. Popular in gardens, front yards, homes and businesses alike.
ornamental tree: Generally, a small tree as opposed to a tall, or shade, tree. Often they are flowering trees used as understory plantings, or massed in the open for color and texture.
orthodox seed: Seed that can be dried to moisture levels between 4 and 6 percent and stored without spoiling.
orthotropic: Tending to grow or form along a vertical axis.
orthotropous: Describes an ovule or seed that is erect, with the orifice or micropyle at the apex.
osmosis (adj. osmotic): The diffusion of liquid through a semipermeable membrane (such as a cell wall) until there is an equalconcentration on both sides of the membrane. The process by which water is taken up through the roots of a plant and transported throughout the structure.
osseous: Bony and brittle.
ostiole (adj. ostiolar): A small opening or pore.
outbreeding: The interbreeding of distantly related or unrelated individuals.
outcross: 1. A cross between relatively unrelated individuals. 2. The offspring of an outcross.
oval: Egg-shaped. See also: ovate, oviform.
ovary: The part of the pistil that contains the ovules.
ovate: Egg-shaped, with the broader end at the base. See also: oval, oviform.
overhead watering: Watering from above, usually with a sprinkler or a hose with a sprinkler attachment.
overstocked: 1. Refers to a stand that contains more trees or other materials than the site can support, causing tall, weak growth and the tendency to blow down. 2. Refers to a range which has more wildlife or domestic stock than the area can support. See also: fully stocked, understocked, carrying capacity.
overtopping: When one branch of a dichotomy grows more than the other.
overwinter: 1. To survive the winter. 2. To keep alive through winter, e.g., bringing a nonhardy plant indoors, wrapping roses or mulching pansies.
ovid: Broadly elliptical.
oviform: Shaped like an egg. See also: oval, ovate.
oviparous: Producing female reproductive cells.
ovoid: A solid with an oval outline.
ovule: The body which, after fertilization, becomes the seed.
ovuliferous: Bearing ovules.
pachycarpous: Describes a seed having a thick outer layer or pericarp, e.g., the skin on a cherry. The skin (epicarp, ectocarp, or exocarp), flesh (mesocarp or sarcocarp), and stony outer layer of the seed (endocarp) forma pachycarpous covering of the seed proper.
pachycaul: With thick or massive primary construction.
pachydermous: Thick-skinned; applied to the walls of capsules or to cells when firm and resisting.
pack ice (alt. ice pack): A large area of ice driven closely together.
pagoda: A tower of Far Eastern design usually with roofs curving upward at the division of each of several stories and erected as a temple; a similarly styled garden structure.
paired: Refers to flowers or leaflets in opposite pairs, but bi-, tri-, and multijugate further describe leaflets with two, three, or many such pairs or parts.
palate: A rounded projection of the lower lip of a personate corolla, closing the throat.
palea (syn. palet): The upper bract which, with the lemma, encloses the flower in grasses.
paleaceous: Clothed with chaff.
Paleobotany (syn. archeobotany): The study of plant fossils.
paleophytological: Relates to the study of fossil plants.
palisade: Refers to the layer of columnar photosynthetic cells in the leaf.
palm: Any of various plants of the family Palmae, mostly tropical or subtropical monocotyledonous trees, shrubs, or vines, usually having a simple stem and a terminal crown of large pinnate or fan-shaped leaves.
palmate (adj. palmately): Describes a leaf that is radially lobed or divided.
palmate-veined: With the principal veins arising from the end of the leafstalk and radiating toward the edge of the leaf.
palmately compound: Having veins or leaflets arranged like the fingers on a hand.
palmatifid: Describes a leaf which is deeply, but not completely, divided into several lobes.
palmatisect: Intermediate between palmate and palmatifid.
palustrine: Refers to areas that are not part of a major lake, but are filled with partially decomposed plant materials to considerable depth in wetlands such as bogs, swamps, and marshes. See also: peat.
palustrine wetlands: Those not a part of a main lake, therefore not subject to intensive wave or current effects.
palynology: The scientific study of pollen and spores.
pampas: An extensive, generally grass-covered plain of temperate South America, located east of the Andes and mostly in Argentina.
pan: A layer of different soil below the surface, often impervious, which would be called hard pan.
panacea: A remedy for all ills or difficulties; cure-all.
pandurate (syn. panduriform): Fiddle-shaped; with a rounded base, narrow waist, rounded upper part and long neck.
panicle: A loose, irregularly compound inflorescence with pedicellate flowers.
panicled (alt. paniculate): Borne in a panicle; resembling a panicle.
pannose: Like felt in texture, densely covered with hairs.
pantoporate: Describes a pollen grain having rounded apertures all over the surface.
pantropical: Spanning tropical regions around the world.
papilionaceous: Describes a corolla having a standard, wings, and keel, as in the peculiar corolla of many Leguminosae.
papilla (pl. papillae): 1. A minute, nipple-shaped projection. 2. Small bumps appearing on either the upper cortex or lower surface of various lichens.
papillaer: Minute rounded or acute protuberances.
papillate: Bearing papillae.
papillose (syn. scabrose): Bearing minute nipple-shaped projections; rough with papillae.
pappus: The modified calyx-limb in Compositae, forming a crown of various character at the summit of the achene.
papule: A relatively large pustule, papilla, or pimple.
papyraceous: Paper-like.
paraclade: An inflorescence on a lateral axis which repeats the symmetry of the primary axis.
paradichlorobenzene: A white crystalline compound used in moth balls and moth crystals and often placed with herbarium specimens to prevent destruction by moth larvae. Large quantities in a closed container may be used to kill insects needed as part of sample.
parallel-ribbed (syn. parallel-veined, syn. parallel-nerved, syn. penniparallel): With the veins running more or less parallel toward the tip of the leaf.
paraphyllia: Minute leaf-like or much-branched organs among the leaves.
paraphysis (pl. paraphyses): 1. Jointed hyaline hairs growing among the reproductive organs. 2. The thread-like hyphae between the asci.
parasite: A plant deriving its nutrition from another organism; the dependent member of parasitism.
parasitization: The process whereby one organism lives on or with another as a parasite.
parenchyma: Soft tissue of cells with unthickened walls.
parenchymatous: Cells with broad ends abutting on each other, not dovetailing into each other.
parietal: Borne on or pertaining to the wall or inner surface of a capsule.
paripinnate: Having an even number of pinnae. See also: imparipinnate.
parkland: Land in which clumps of trees are scattered throughout a grassland. See also: parks.
parks: Areas set aside by government and kept in their natural states for the purpose of conserving unique areas for preserving game, walking, riding, or recreation.
paroicous: Having its male and female organs in the same cluster, but not mixed, the antheridia being in the axils of the perichaetial bracts below the archegonia.
parterre: A formal garden of intricately designed, geometrically shaped beds of flowers, herbs, and low shrubsseparated by pathways and/or lawns.
parthenocarpic: Refers to the fruiting of plants which have not been pollinated or otherwise fertilized.
parthenogenetic: Developing without fertilization.
partial: Of secondary rank.
partite: Parted.
partitioned: The pith divided crosswise by woody plates, usually near the leaf scars.
pasture: A grassland which is used as graze for domestic animals.
patellate (alt. patelliform): Round and thick, with one side concave and the other following the same curve by being convex, like a thick contact lens.
patent (alt. patulous): Spreading, as do the branches of a tree; particularly at an angle of 26-45 degrees.
pathogen: A disease-causing agent, especially a bacterium, fungi, or other microorganism.
pathological: Diseased.
patina: The changed color or texture of a surface due to weathering or aging.
patulous: More widely spreading than patent.
pea-like: Refers to a flower with a top banner or standard, similar to legume blossoms; papilionaceous.
peat bog: An area with a wet, spongy, acidic substrate, consisting mainly of accumulated layers of sphagnum mossand upon which other plants, and even trees, can grow.
peat moss: Partially decomposed sphagnum moss, often added to soil to increase moisture retention.
peavey (alt. peavy): A tool similar to a cant hook, but with the tip outfitted with an iron spike rather than a ring.
pectin (adj. pectic): Any of various water-soluble substances that bind adjacent cell walls in plant tissues and yield a gelwhich is the basis of fruit jellies.
pedicel: 1. A tiny stalk; the support of a single flower. 2. The stalk of the sporangia. See also: seta.
pedicelled (alt. pedicillate): Borne on a pedicel.
peduncle: A primary flower stalk, supporting either a cluster or a solitary flower.
peduncled (alt. pedunculate, alt. peduncular): Borne upon a peduncle.
pegging: Securing the ends of canes to the ground so that the plant grows horizontally.
pellucid: Clear, transparent.
peloria (adj. peloric): Unusual regularity or symmetry in the form of a flower that is normally irregular.
peltate: 1. Describes a leaf attached to the petiole from near the center of the lower surface, and not at the margin. 2. Shield-shaped.
pendant: Hanging downward.
pendular: Having the movement of a pendulum.
pendulous: More or less hanging or declined. Pendulous ovule: one that hangs from the side of the cell.
penicillate: Tufted with small hairs.
penniribbed (syn. penninerved, syn. penniveined): Having conspicuous lateral veins which are divergent from the midrib and approximately parallel to one another.
pentamerous: Describes a flower which has five parts in each floral whorl.
pentangular: With five angles, as the cross-section of a stem.
pentaploid: Having five sets of chromosomes.
pepo: A fruit, such as that of a melon or squash, having a firm rind, fleshy pulp, many flattened seeds, and a single locule.
perched water table: The water table of a smaller body of groundwater body situated above the general groundwater table.
percurrent: Describes a costa that reaches to the apex of the leaf, but not beyond.
perennate (n. perennation): To live for more than one growing season, but usually with reduced growth or dormancy between growing seasons.
perennial: A plant whose life cycle lasts for three or more seasons; Lasting year after year.
perfect: Describes a flower having both pistil and stamens.
perfoliate: Describes a leaf having the stem apparently passing through it.
perforate: Pierced with holes.
pergola: An open structure usually consisting of parallel columns supporting an open roof of cross rafters on which climbing plants are trained to grow; an arbor.
perianth: The floral envelope, consisting of the calyx and corolla (when present), whatever their form.
pericarp (syn. fruit wall): The wall of the matured ovary.
perichaetium (pl. perichaetia, adj. perichaetial): A whorl of bracts at the base of reproductive organs. In mosses, those surrounding the archegonia and base of seta.
pericycle: The tissue of the stele lying just inside the endodermis.
periderm: An outer, cortical protective layer of many roots and stems that typically consists of phellem, phellogen, and phelloderm.
perigone: The perianth, especially when made up of tepals, or in reference to anything surrounding the reproductive structure.
perigonium (pl. perigonia, adj. perigonial, syn. perigone): 1. The perianth. 2. In mosses, those bracts surrounding the antheridia.
perigynium: The inflated sac which encloses the ovary in Carex.
perigynous: Adnate to the perianth, and therefore around the ovary and not at its base.
periodicity: Repetition of events at fairly regular intervals.
peripheral: On or near the margin.
periphyton: The assemblage of organisms submerged in water, attached to surfaces above the bottom of the body of water. See also: benthos, plankton.
perisperm: The nutritive tissue in an angiosperm seed that surrounds the embryo, formed from the nucellus. See also: endosperm.
peristome: The fringe surrounding the mouth of the capsule upon removing the lid.
perithecium (pl. perithecia): A small flask-shaped structure, containing asci.
perlite: A lightweight aggregate made from a volcanic glass that has been expanded by heat to form white, very lightweight kernels useful in opening cavities in soil to allow water and air to reach the roots; often used in potting soil.
permaculture: The maintaining of a permanent horticulture or agriculture by relying on renewable resources and compatibility with the local ecosystem.
permafrost: Frozen ground in arctic and subarctic areas which does not thaw in summer.
persistent: Lasting beyond maturity without being shed, as some leaves remaining through winter, etc.
personate: Describes a corolla which is bilabiate, and the throat closed by a prominent palate.
perula (pl. perulae, alt. perule): 1. One of the scales of a leaf bud. 2. A pouchlike portion of the perianth in certain orchids.
perulate: Describes leaf buds which are covered with scales.
petal: A division of the corolla; one of a circle of modified leaves immediately outside the reproductive organs, usually brightly colored.
petaliferous: Bearing petals.
petaline: Of or resembling petals.
petaloid: 1. Colored and resembling a petal. 2. Additonal floral parts on ray florets having the form and appearance of smaller petals, e.g., in the Collarette dahlias.
petiolate: Having a petiole.
petiole (syn. leafstalk): The stalk of a leaf that attaches to the stem.
petiolulate: Having a petiolule.
petiolule: The stalk of a leaflet.
phanerogam: A general name for flowering plants.
phaneropore: Superficial stoma.
phellem: A layer of usually suberized cells produced outwardly by a phellogen.
phelloderm: A layer of parenchyma produced inwardly by a phellogen.
phellogen (syn. cork cambium): A secondary meristem that produces phellem and phelloderm in the periderm of a trunk or stem.
phenetic classification: The grouping of taxa by apparent similarities rather than evolutionary genetics.
phenology (adj. phenological): The science of the relations between climate and periodic biological phenomena, e.g., the fruiting of plants or the color change of leaves.
phenotype: The morphological, physiological, behavioral, and other outwardly recognizable adaptations of an organism that develop through the interaction of genes and environment. See also: genotype.
phenotypic: Refers to a plant's adaption to surrounding conditions, which are neither stable nor capable of being inherited (genotypic). Such visible changes occur especially where plants are grown in a wide variety of conditions, but will not carry over to different conditions, e.g., red leaves may occur in hot dry areas, but turn green when grown in normal conditions.
pheromones: Chemical substances produced by animals that attract and stimulate sexual partners of the same species.
photic zone: The upper layers of bodies of water into which sunlight penetrates sufficiently to influence the growth of plants and animals. See also: aphotic zone.
photohetrotroph: Describes an organism using light as a source of energy and organic materials as a carbon source.
photomania (adj. photomanic): The response of an organism of seeking or growing toward light. See also: phototropism.
photomorphogenesis: The formation and differentiation of tissues and organs controlled by radiant energy, particularly light.
photoperiod: The duration of an organism's daily exposure to light.
photoperiodic: Describes growth affected by exposure to light.
photophobia (adj. photophobic): The dislike of light, as displayed by bugs that hide under rocks or bats which sleep all day and fly at night. See also: photomania, aphototropism.
photophosphorylation: The synthesis of ATP from ADP and phosphate that occurs in a plant using radiant energy absorbedduring photosynthesis.
photosynthesis: The manufacturing of sugar through the action of sunlight.
phototaxis: The movement of a body toward or away from a light source.
phototropism (adj. phototropic): Growth or movement toward or away from a light source.
phreatophyte: A plant that can endure inundations of salt, such as cattails, Typha, which can live in estuaries, sieving out the saline molecules of seawater at a cellular level.
phyllary: One of the bracts under the flower head of a plant, especially in Compositae.
phylloclade (alt. phylloclad, syn. cladode, adj. phyllocladous): A flattened, photosynthetic stem that performs the functions of a leaf, as occurs on some cacti. See also: cladophyll.
phyllocladia: Tiny life-like structures of some lichens.
phyllode: A flat expanded petiole that replaces the blade of a foliage leaf and fulfills the same functions. See also: cladophyll.
phyllodium (pl. phyllodia): A somewhat dilated petiole having the form of and serving as a leaf blade.
phyllopodium: An outgrowth of the rhizome to which the frond is joined in some ferns.
phyllotaxy (alt. phyllotaxis): The manner of leaf arrangement on a stem.
phylogenetic classification: The grouping of taxa by genealogical descent; evolution.
phylogeny (adj. phylogenetic): The evolutionary development of a taxonomic group.
phylum: A major taxonomic grouping in the animal kigdom, ranking just below kingdom and above class. In the plant kingdom, it is usually replaced by the division.
physiographic climax: A pinnacle habitat controlled by the topography of the area; e.g., a forest growing on a north slope and a grassland on the south slope of the same ridge. See also: edaphic climax, biotic climax.
phytochemistry (adj. phytochemical): The chemistry of plants, plant processes, and plant products.
phytochrome clocks: The coloring processes of plants that change the hues of ripening fruits and cause leaves to change colors with the shortened days of autumn.
phytogenesis: The evolutionary development of plants.
phytogenic (syn. phytogenous): Having a plant origin, e.g., coal.
phytography: The science of plant description.
phytology (adj. phytological): The study of plants.
phytopathogen: An agent-causing disease in plants.
phytoplankton: Small, often microscopic, aquatic plants.
phytotoxicity (n. phytotoxin, adj. phytotoxic): Being poisonous to plants.
pick: A mattock type tool, which has one or both ends pointed.
pick pruning: The selection of individual branches to be cut; the opposite of shearing.
pier: A mass of masonry used as a support, breakwater, etc.
pilose: Hairy, especially with soft hairs.
pilosulous: Minutely pilose.
pinna (pl. pinnae): One of the primary divisions of a pinnate or compoundly pinnate frond or leaf.
pinnate: Consisting of several leaflets arranged on each side of a common petiole or rachis on a compound leafor frond. 2. The feather vein pattern of simple leaves.
pinnately compound: With leaflets arranged in two rows along an axis.
pinnatifid (syn. pinnatipartite): Divided in a pinnate manner, but with leaflets not entirely separate.
pinnatisect: Deeply cut, all the way to the axis.
pinnule: A secondary pinna; one of the pinnately disposed divisions of a pinna.
pip: 1. The small seed of a fruit, like that of an apple or an orange. 2. An individual rootstock of lily of the valley or a similar plant.
pistil: The seed-bearing organ of the flower, consisting of the ovary, stigma, and style when present.
pistillate: Provided with pistils, and, in its more proper sense, without stamens.
pistillode: A sterile pistil, often rudimentary.
pitch: Lumps of resin found on the bark of trees.
pitcher-shaped: Campanulate, but with a distinct narrowing near the open end.
pith: The spongy or hollow center of twig or some stems.
pitted: Marked with small depressions or pits.
placenta: Any part of the interior of the ovary which bears ovules.
placentation: The arrangement of placentas within an ovary.
plankton: The floating or weakly swimming plants and animals occurring at any depth in bodies of water, often microscopic in size. See also: aeroplankton, edaphon.
plant: Any of the members of the kingdom Plantae typically lacking locomotive movement or obvious nervous or sensory organs and possessing cellulose cell walls and usually capable of photosynthesis.
plant labels: 1. Plastic, wood, or metal stakes for gardens to indicate what seeds are planted where until they appear, and for varieties for evaluation. 2. Paper forms to include in drying plant samples, with formal printed forms as permanent labels on herbarium specimens. The minimum information required are the name of the collector, the location collected, the date collected, and hopefully, the correct identification of the specimen.
plant press (alt. field press): A structure typically made of two ventilated frames 12 X 18 inches (30 X 45 cm.), within which plants may be arranged between sheets of driers and ventilators, tightly strapped together with press straps, in preparation of being added to a collection or herbarium.
plantation: A large farm of cultivated trees or plants, often of a single crop.
plantlet: A small plant, usually one produced vegetatively from a parent.
plasmodesma (alt. plasmodesm, pl. plasmodesmata): One of the cytoplasmic strands that passes through openings in some plant cell walls and provide living bridges between cells.
plasmolysis: The shrinking of the cytoplasm away from the wall of a living cell due to the loss of water through osmosis.
plasticity: Flexibility; adaptability; capable of being repeatedly deformed without rupture.
plastid: Any of various cytoplasmic organelles of photosynthetic cells that serve in many cases as centers of special metabolic activities, e.g., chloroplasts.
plates: Flattened, rhizine-like structures on the lower surface of some lichens.
pleaching: A process whereby branches of woody plants are interwoven and plaited together to form an impassible hedge or very thick arbor. The only pruning done is to maintain a neat formal shape.
pleated: Describes a leaf creased along its length.
pleomorphic (n. pleomorphism): Able to assume different forms.
pleurocarpous: Having the sporophyte lateral on a short lateral special branch. Pleurocarpous mosses can usually be recognized by the creeping habit.
plicae: Folds of a plicate leaf.
plicate: Folded into plaits, usually lengthwise.
plow: A device used to turn soil. On large farms several of these are mounted in a diagonal line, and referred to by the number of blades, e.g., a six-bottom plow. For compacted soil, chisels, four feet (1.3 m.) or longer, are used to open greater depth, and are called chisel plows.
plug: A core of grass sod or wildflower turf used in planting lawns and meadows.
plume: A feathery inflorescence.
plumose: Having fine hairs on each side, like the plume of a feather, as the pappus-bristles of some thistles.
plumule: The bud or growing point of the embryo.
plur- (alt. pluri-): A prefix meaning many, e.g., plurilocular means many-celled.
plurilocular: Describes a sporangium or gametangium composed of many cells, each producing one zoospore or gamete.
pluriseriate: Many-ranked, as applied to leaves arranged in several rows along the stem.
pneumatophore: A specialized root in certain aquatic plants which performs respiratory functions.
pocket beach: The shore at a bay head where wave energy is lowest and settlings highest, often with fringe wetlands.
pod (syn. seedpod): Any dry, several-seeded and dehiscent fruit.
podetium: A hollow upright structure.
polarity: The tendency for plants to develop from its poles, roots growing down, stems growing upward, making it essential to plant bulbs, etc, in the correct position.
pole pruner (syn. pruning stick, syn. pole saw): A pruner on an extensible pole--usually having a curved saw at its end--which can be used to prune the upper parts of a tree or tall shrub.
pollarding: A process where tree tops are cut back severely each year to the same spots on the branches. This forces the growth of large knobby stubs from which long tender shoots grow each year.
pollen: The microspores of a seed plant contained in the anther, usually appearing as a fine dust.
pollen grain: A microspore of a seed plant.
pollen sac: The microsporangium of a seed plant where pollen is produced; the upper portion of the stamencontaining pollen grains; the anther.
pollinate (n. pollination): To transfer pollen from the anther of a stamen to the stigma of a pistil, resulting in fertilization. This can occur either on a single plant (self-pollination) or between different plants.
pollinator: The agent, such as an insect or wind, which carries the pollen for fertilization.
polliniferous: Bearing pollen.
pollinium (pl. pollinia): A mass of waxy pollen or of coherent pollen grains, as found in Asclepias and Orchidaceae.
polyad: 1. A set of molecular states connected by vibratory resonances. 2. A patented name for the adsorptionprocess for the removal and destruction of Volatile organic compounds (VOC).
polybrid: A hybrid with more than two parental groups.
polyembryonic: Containing two or more embryos.
polyethylene: A plastic which allows the passage of gases but not of moisture.
polygamodioecious: Describes a plant group which has bisexual and male flowers on some plants, and bisexual and female flowers on others.
polygamous: 1. Bearing male and female flowers on the same plant. 2. Having antheridia and archegonia disposed in various ways on the same plant.
polymorphic: Having more than two distinct morphological variants.
polypetalous: Having separate petals.
polyphyletic: Having members that originated, independently, from more than one evolutionary line. See also: monophyletic.
polyploidy (n. polyploid): Having more than two sets of chromosomes in cells of the sporophyte or more than one set in cells of the gametophyte.
polysepalous: Having a calyx made up of separate sepals.
polystichous: Having leaves or other structures arranged in distinct rows.
polytrichous: Covered with many hairs.
polytypic: Containing more than one taxon of the next lower rank, e.g., a genus with more than one species. See also: monotypic.
pome: A kind of fleshy fruit, particularly an apple.
pompon: A small globular flower or flower head.
pond: A small, still body of water; an artificial body of water in a garden usually containing aquatic plants and fish.
pondweeds: A popular name for species of wetland plants that grow partially or wholly underwater.
pool: A small and relatively deep body of usually fresh water, either standing or as part of a stream. There is little wave action and often a reflective quality.
population: Plants of a species growing in a given place at a given time. Two similar species may mingle, e.g., Solidago canadensis and Solidago altissima, but the botanical term 'population' would include one species or the other, not both.
population density (syn. species density): The concentration of individuals in relation to the space they occupy; how close individuals occur. See also: abundance, cover.
porate: Describes a pollen grain which has rounded apertures only. See also: colporate.
poricidal: A type of dehiscence in which the pollen is released through pores at the tip of the anther.
porose: Pierced with small holes or pores.
porrect: Spreading outward and forward.
Portland cement: A cement consisting predominantly of calcium silicates which reacts with water to form a hard mass.
positive drainage: Surface or underground pipes or trenches to remove excess water.
posterior: In an axillary flower, on the side nearest to the axis of inflorescence.
postreproductive: Refers to an organism which is past the age of breeding capacity.
potato fork: A fork of heavy construction with flat tines, for deep digging as is needed for potato harvesting.
potbound: The condition of a houseplant or outdoor container plant which has been left in the same pot or container for too long a period of time and the roots fill every niche of the pot or container. A hook or blade is required to cut through and separate the tangled matted outer roots when removed from the pot and before placing in the new container or the plant may never recover from this disastrous condition.
potential Hydrogen (abr. pH): A log scale measurement of the acidity/alkalinity of a solution with 1 being extremely acidic, 10 being extremely alkaline, and 7 being neutral. Most plants prefer a soil within a certain range of pH.
potherb: A plant whose leaves, stems, or flowers are cooked or used as a seasoning.
pothole: 1. A pond or pool utilized by waterfowl for nesting and raising young. 2. A hole worn in solid rock by the action of water, especially when a pebble repeatedly spins in the depression.
poultice: Moist, usually hot, mass of plant material; wrapped in a cloth and applied to the skin to bring about some desired action, such as bringing a boil to a head.
powdery mildew: A fungus forming a white powdery coating on leaves and stems.
power take off (abr. PTO): Unit on a tractor to attach power tools.
Pozzolan cement: Volcanic rock powdered and used in making hydraulic cement.
pradines: Lopping tools.
praemorse: Appearing as if bitten off.
prairie: Grasslands, particularly that which formerly covered much of the central plains of North America, consisting of rich soil and a variety of grasses and forbs and generally covering a wide area.
precocious: Occurring early, as flowers appearing before the leaves; hysteranthous.
preemergent (alt. pre-emergent): An herbicide, or combination fertilizer and herbicide, that is applied to a lawn early in the season, before the new growth has occurred.
prereproductive: Refers to a plant or animal which has not yet matured sexually.
prescribed burning: The intentional burning of plant material in an area. Sometimes used to consume underbrush and other fuel and thus prevent larger, more destructive fires. Also used to maintain a stable prairie or grasslandby aborting the process of succession to shrubs and trees.
press straps (syn. web straps): Bands or ropes to hold the plant press tightly together, traditionally made of web and buckles, but now often with Velcro.
prevernal: Appearing in late winter or very early spring, as do crocus flowers.
prickle: A small, sharp outgrowth involving only the outer epidermal layer, usually more slender than a thorn. This is the correct term for rose thorns.
primary forest (syn. natural forest): A tract of trees with minimal impact from humans.
primocane: The floricane, but in the first year of growth before it is capable of flowering.
primordial utricle: The layer of protoplasm lying next to the cell wall, which is very often conspicuous when dried and shrunken.
primordium: A tissue or organ in the early stages when it has undergone differentiation changes but has not yet matured enough to emerge.
priority: The rule of nomenclature whereby the first published of two validly published names for the same entity is given approval as the accepted name.
prismatic: Of the shape of a prism, angular, with flat sides, and of nearly uniform size throughout.
pro hybrida (abr. pro hybr.): Means "as a hybrid." Used in citations to show that a plant now known as a species started as a hybrid.
pro parte (abr. p.p.): Means "in part". Used in citations to show that a taxon as used by one author shows only a portion of what was intended by the original author.
pro specie (abr. pro sp.): Means "as a species." Used in citations to show that a plant which had been accepted as a species is now designated as a hybrid.
proboscis: Beak.
procumbent: Lying on the ground or trailing but without rooting at the nodes.
profundal zone: The area of deep water at the bottom of a lake below effective penetration of light. See also: abyssal.
projecting: Refers to stamens, styles, and stigmas which exert beyond the petals of a flower.
prokaryote (alt. procaryote, adj. prokaryotic, adj. procaryotic): An organism composed of one or more cells lacking a visibly evident nuclei, including the viruses, bacteria, and cyanobacteria. See also: eukaryote.
proliferous (syn. proliferating): 1. Freely producing offshoots, bulblets, or plantlets. 2. In mosses, bearing young shoots from the antheridial or archegonial cluster of leaves.
prominent: Standing out from the surface, clearly visible and touchable, as are veins and other surface features.
prominulous: Slightly raised above the adjoining tissue.
propagate (syn. propagation): To produce new plants, either by vegetative means involving the rooting or grafting of pieces of a plant, or by sowing seeds.
prophyll: 1. The bracteole under a single flower or pedicel. 2. The showy first bract borne on the peduncle and, occasionally, on the inflorescence branches of some monocots.
prosenchymatous: Cells with pointed ends dovetailing into each other.
prostrate: Lying flat upon the ground.
protandrous: Refers to a flower where the shedding of the pollen occurs before the stigma is receptive. See also: protogynous.
protected area: A legally restricted land or water area under public or private ownership, which has managed to achieve specific conservation objectives.
proteinaceous: Of, relating to, resembling, or being protein.
proterogynous: Having the stigma ripe for the pollen before the maturity of the anthers of the same flower.
prothallium (pl. prothallia): The minute scale-like growth from the spore of a fern.
prothallus: A cellular, usually flat and thallus-like growth, resulting from the germination of a spore, upon which are developed sexual organs or new plants. The gametophyte stage of ferns.
protogynous (syn. proterogynous): Refers to a flower where the shedding of the pollen occurs after the stigma has ceased to be receptive. See also: protandrous.
protologue: Refers to all parts of botanical publication, including, but not limited to, diagnosis, description, synonymy, citation of specimens, illustrations, etc., expressed as data, information, and knowledge.
protonema: The green, branched, alga-like threads produced from the spore and often persistent during the lifetime of the plant produced from it.
protoplasm: The living contents of a cell.
protoxylem: The first formed xylem.
proximal: Toward the base.
proximate: Close together.
pruina: A woolly white covering of the upper cortex of some lichens.
pruinose: Having the surface obscured by a rather thick, bluish or grayish, wax-like coating.
prune: To cut back, for the purposes of shaping a plant, encouraging new growth, or controlling size.
pruning saw: A serrated blade tool for cutting small limbs; may be styled so the blade folds into the handle, or fit into a sheath.
pruning shears: Specialized scissors to cut plants back.
pseudanthium (pl. pseudanthia): An inflorescence which looks like a simple flower, but is made of more than one axis with a number of flowers.
pseudobulb (adj. pseudobulbous): A swelling at the base of a stem in which epiphytic orchids store nutrients and water.
pseudocarp (syn. accessory fruit, syn. false fruit): A fruit, such as the strawberry or pear, that develops not only from the ripened ovary, or ovaries, but from nonovarian tissue as well.
pseudocyphellae: Pores found in the upper or lower cortex of lichens.
pseudolamina: A false lamina, one usually formed by the lateral expansion of a rachis.
pseudoparenchyma: Filamentous tissue compacted to resemble parenchyma.
pseudopodetium: An upright, fruticose thallus of some lichens.
pseudopodium: A leafless branch resembling a seta and often bearing gemmae.
pseudopods: Literally, false feet; a temporary protrusion of the protoplasm of a cell for the purpose of moving or feeding; foot-like organs.
pseudostem: An erect aerial growth which appears to be a stem with leaves, but is actually packed or overlapping sheaths and stalks of essentially basal leaves.
pseudoterminal: 1. Describes a bud which is situated at what appears to be the apex of a branch, but is in fact located in an axillary position beside a leaf scar. 2. Refers to a bud which replaces an injured terminal bud which has died.
pteridology (n. pteridologist, adj. pteridological): The study of ferns.
pteridophyte: Any of the nonflowering vascular plants of the division Pteridophyta having roots, stems, and leaves; a fern or fern ally.
Pterophyta: A major taxonomic division containing the ferns, showing clear alternation of generations with a dominant vascular sporophyte which begins with the very reduced gametophyte.
puberulose (alt. puberulent, alt. puberulous): Minutely pubescent.
pubescence: A covering of soft, short hairs.
pubescent: Covered with hairs, especially if short, soft, and down-like.
puddle: 1. A very small pool of water, often transitory, appearing during heavy rain and disappearing shortly afterward. 2. To knead or work soil while wet, making it impervious to water. 3. To work while wet, as in flooded rice fields.
Pulaski clearing axe (alt. Pulaski): A tool used mostly by firefighters that is a combination of axe and grub hoe.
pulp: 1. The soft, succulent part of a fruit, usually composed of mesocarp. 2. The pith of a stem.
pulpwood: The wood of trees like aspen, Populus, and spruce, Picea, which is easily ground into a soft mass for the production of paper.
pulverulent: Powdered; appearing as if covered by minute grains of dust.
pulvinate: Like a cushion.
pulvinus: A swelling at the base of the stalk of a leaf or leaflet.
punctate: Dotted with depressions or with translucent internal glands or colored dots.
puncticulate: Minutely punctate.
pungent: Terminating in a rigid sharp point; acrid to smell or taste.
purgatives: Medicines which empty the intestines.
pustular: Like a blister.
pustulate: Covered with blisters.
pustule: A surface eruption such as a pimple or blister.
putamen: The shell of a nut; the bony part of a stone fruit.
PVC sleeves: A plastic pipe used for moving water that acts as a conduit.
pycnidium (pl. pycnidia): A rounded or flask-shaped asexual fruiting body containing spores found in certain fungi.
pyramidal: Conical with flat angular sides.
pyrene: The stone of a succulent fruit made up of the endocarp and the seed. See also: drupe.
pyrethrin: The pyrethrins are a class of organic compounds normally derived from Chrysanthemum cinerariifolium that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin is synthetically made by industrial methods, but it also naturally occurs in chrysanthemum flowers, thus is often considered an organic insecticide.
pyriform: Pear-shaped.
pyxis: A capsule which opens in a circumscissile manner.
quadrate: Describes cells that are square or nearly so.
quadrifid: Divided into four parts.
quadrilateral: With four sides.
quadrinary combination: Binomial plus two more taxon names such as subspecies and variety.
quadripinnate: Four times pinnate.
quarantine: A legal ban on the export or import of certain noxious weeds or insects that may be attached to the plants.
quartered: Having the petals formed into a number of sections, usually four but sometimes three or five.
quinate: Having five leaflets growing from the same point of attachment.
quincunx (alt. quincunce, adj. quincuncial, adj. quincuntial): The arrangement of five objects, such as trees, with one on each of four corners and one in the center.
raceme: A simple inflorescence of pediceled flowers upon a common more or less elongated axis.
racemiform: Refers to an inflorescence with the outward appearance of a raceme.
racemose: Resembling a raceme.
rachilla: The axis of a spikelet, particularly in grasses.
rachis: 1. The main stalk of a flower cluster or the main leafstalk of a compound leaf. 2. In ferns, the continuation of the stipe through a compound frond.
radial: In flowers, one with the symmetry of a symmetry wheel.
radiate: Spreading from or arranged around a common center; bearing ray flowers.
radical: Belonging to or proceeding from the root or base of the stem near the ground.
radicle: The portion of the embryo below the cotyledons that will form the roots, more properly called the caudicle.
radicles (alt. rhizoid): Rootlets springing from the sides and base of the stem.
radius (pl. radii): 1. The outermost flowers in a daisy-like head, Compositae; ray flowers as opposed to disc flowers. 2. The distance from the center of a circle to the outer edge, as from the heart of a tree to the bark.
raffia (alt. raphia): A fiber-like material used for tying grafts and other horticultural purposes.
raised beach: An old beach terrace at an elevation above the present shoreline, representing a formerly higher lake level.
raised bed (syn. raised garden): A bed or garden created by adding soil on top of that which is already present. This is usually done in cases where the underlying soil is particularly poor in nutrients or has inadequate drainage. Wooden or stone walls are often used to keep the added soil in place.
ramble: To grow freely, often over another plant or structure.
rameal: Belonging to a branch.
ramentaceous: Refers to stems or leaves which have small, loose, brownish scales.
ramet: 1. An individual member of a clone. 2. An underground tree system giving rise to large suckering colonies, like big-tooth aspen trees, Populus grandentata.
ramification: Branching.
ramiflorous: Bearing flowers directly from large branches and leafless twigs, but not on the trunk.
ramiform: With branches; branch-like.
ramose: Having many branches.
ramuli: Minute branchlets.
ranch (alt. ranche, rancho): 1. In the united States and Canada, a farm that raises livestock, fruits, and vegetables for use of the family, or crops for feeding animals; sometimes used as a secondary income, e.g., a cattle ranch. 2. The buildings occupied or the persons on the estate (ranchers).
range of variation: The extremes of possibilities which may occur within a species and still remain a member of that species, including such things as leaf shape, leaf margins, flower color, height, etc.
rank: 1. A vertical row, as of leaves. When you sight along the length of a branch from the tip end, if it appears there are two rows of leaves, either opposite or alternate, the branch is 2-ranked; if three rows, it is 3-ranked, etc. 2. In taxonomy, the position of a taxon in the hierarchy, e.g., species, genus, family, etc.
raphe: The part of the funiculus that is fused along the side of the ovule.
raphides: Needle-like crystals of calcium oxalate that occur in bundles in some plant cells.
ratchet tool: One which uses mechanical means to multiply cutting or turning power, reducing cramping of hands and forearms.
ravine: A depression worn by running water, larger than a gully and smaller than a valley.
ray: The branch of an umbel; the marginal flowers of an inflorescence when distinct from the disk.
ray floret: One of the broad, conspicuously colored florets of a compound flower, the structure of which suggests a single petal of an ordinary flower. These form the radiating border in the open-centered type dahlias, or massed together, the flower head in fully double types. See also: disc floret.
ray flower: The bilaterally symmetrical flowers around the edge of the head in many members of Compositae; each ray flower resembles a single petal.
rays: Radial strands of cells in wood and phloem.
recalcitrant seed: Seed that does not survive drying and freezing.
receptacle: 1. The more or less expanded or produced portion of an axis which bears the organs of a flower (the torus) or the collected flowers of a head, and in roses, enfolds the developing ovaries to form a hip. 2. Any similar structure in cryptogams.
receptacular: Carried on the receptacle; pertaining to the receptacle.
recession: A drop in the water line of a body of water, with a corresponding exposure of the bottom.
reclinate: Bent or turned downward.
reclining: The lower portion somewhat flattened along the ground but the upper parts curving upward.
recurved: Curved downward or backward; with ray florets curved backward along their length toward the stem.
reeds: Tall thin wetland plants of the genera Phragmites and Sparganium; a term often incorrectly applied to bulrushes.
reel mower: A grass-cutting tool on which helical blades spin against a flat surface, generally hand powered but may be mechanized for a more precise cut than rotary mowers.
reference: A citation to a source of information, such as a written document.
reflexed: Abruptly bent or turned downward.
refrigerants: Herbal preparations which cool the body.
regular: Uniform in shape or structure.
regular flower: Generally symmetrical and uniform in the number of its parts.
rehabilitation: The process of improving specific ecosystem factors in a degraded habitat.
rejuvenation pruning: The practice of cutting all the main stems of a shrub back to within half-inch of the ground during winter dormancy.
relict (alt. relic): A species or other group within a community that is representative of an earlier stage of development or of a different set of conditions.
relief: The difference in elevation between the highest point and the lowest point of land in a specified region.
remontant: Able to rebloom one or more times during a single growing season.
remote: Distant, at the farthest end.
renewal pruning: The practice of cutting all the main stems of a shrub back to within half-inch of the ground during winter dormancy.
reniform: Kidney-shaped.
repand: With a slightly uneven and somewhat sinuate margin.
repellent: A substance used to keep insects or animals from an area.
repent (alt. repen, syn. reptant): Creeping; prostrate and rooting at the nodes.
replicates: Duplicate specimens.
replum: The hardened framework of the placenta which remains when the outer walls or valves of a silique fallaway; the septum which holds the seeds.
resin: A plant secretion, often aromatic, that is insoluble in water but soluble in ether or alcohol.
resin dot: Tiny circular or globular yellow spots, usually not obvious except under magnification.
resiniferous: Producing resin.
resinous: Coated with a sticky gum or resin.
restoration: The return of an ecosystem or habitat to its original structure, natural complement of species, and natural functions.
resupinate: Turned upside down.
resupine: Refers to a flower or leaf on which the stalk twists a full half turn, 180 degrees, so that the organ appears to be upside down.
retardants: Admixtures that increase the setting time of cement by slowing down hydration.
retentive sepals: Sepals that remain attached to the apex of the receptacle after it has ripened into a hip.
reticulate: In the form of network; netveined.
reticulation: The entire network of reticulate veins, ribs, coloring and/or fibers.
reticulum (pl. reticula): A mesh-like network.
retinaculum: The structure by which another structure is attached to a plant.
retrorse: Directed back or downward.
retting: Soaking plant tissue so as to induce bacterial growth that will aid in the separating of the fibers.
retuse: With a shallow notch at a rounded apex.
reversion: When a genetically differentiated plant or sport reverts to normal growth. For instance, variegatedleafs turn green.
revolute: Rolled backward from the margins or apex; describing a ray floret with margins rolled backward along their longitudinal axis. See also: fully revolute.
rhachilla: A secondary axis; specifically, in the grasses and sedges, the floral axis as opposed to that of the spike or spikelet.
rhachis: The axis of a spike or of a compound leaf.
rhape: The ridge or adnate funicle which in an anatropous ovule connects the two ends.
rhaphides: Needle-shaped crystals often occurring in bundles within the cells of certain plants.
rhizines: Strands of hyphae found on the lower surface of many foliose lichens.
rhizobia: Bacteria in a symbiotic relationship with leguminous plants that results in nitrogen fixation.
rhizomatous: Having or appearing to have rhizomes.
rhizome (syn. rootstock, syn. understock, adj. rhizomatous): Any prostrate or subterranean stem, usually rooting at the nodes and becoming erect at the apex.
rhizome chaff: Small pieces of rhizomes which are spread upon the ground and covered with soil so they can take rootand form new plants.
rhizome cutting: A piece cut from a rhizome which can take root and form a new plant.
rhizosphere: The area that surrounds and is influenced by a plant's roots.
rhombic: Diamond-shaped.
rhomboid: Refers to leaves, tepals, etc., which are diamond-shaped, with the base and tip having acute angles and the sides having obtuse angles.
rib: A primary or prominent vein of a leaf.
ribbed: With one or more prominent veins or nerves.
ribs: Geologic ridges running parallel, as often occurs along a mountain side.
ridged: Angular, with lengthwise lines.
rind: 1. The bark of a tree outside the cambium layer. 2. The epicarp of a citrus fruit, e.g., an orange or a lemon.
ringed: Having narrow encircling stipule scars around leaf scars.
ringent: Gaping, as the mouth of an open bilabiate corolla.
riparian: Of, or relating to, rivers or streams.
ripening: 1. The maturing of a fruit as developmental changes prepare it for seed dispersal. 2. The hardening of wood, especially of soft twigs, important in taking cuttings for propagation.
risers: The up and down sections of stair steps; necessary for landscape plans.
riverine: Refers to a river.
rivermouth: The place where a river empties into another body of water.
rock garden: A garden laid out among rocks and adapted for the growth of particular kinds of plants, such as alpines.
rolled: Curled under; revolute.
root: The underground part of a plant that serves to anchor it and supplies it with nourishment.
root cutting: A cutting taken from the root of a parent plant for the purpose of propagation.
root knot: A disease of the roots characterized by a swelling and caused by nematodes.
root pruning: 1. Pruning to stimulate the growth of new roots within a parameter in preparation for transplanting. 2. Trimming and/or scoring the outer layer of roots of a plant that has become root bound. 3. The act of removing a portion of a plant's roots to keep top growth in check.
root zone: The area immediately surrounding the roots and from which a plant takes moisture and nourishment.
rootball (alt. root ball): The root stock and surrounding soil together; in nurseries and during transport, these are held together by burlap or other wrapping.
rootbound (alt. root bound): The condition of a houseplant or outdoor container plant which has outgrown its container, with the roots filling every niche of the container. Eventually, the roots will themselves strangle the plant by constricting the flow of nutrients. A hook or blade is required to cut through and separate the tangled matted outer roots when removed from the pot and before placing in the new container.
rootlet: A small, secondary root.
rootstock (syn. rhizome, syn. understock): 1. A rhizome. 2. The root system and lower portion of a woody plant to which a graft of a more desirable plant is attached.
rootworm: The larvae of a beetle of the genus Diabrotica that feed on the roots of various plants, particularly corn.
roridulous (alt. roridulate): Dewy; covered with waxy plates which appear to be dew drops.
rose dethorner: Florist tool to remove the thorns from roses and other flowers.
rose hip: A smooth, rounded, fruit-like structure consisting of the cup-like calyx enclosing seed-like fruits.
rosette: A cluster of leaves which grows in a circular overlapping pattern--somewhat like the petals of a rose--arising basally from a crown, as on a dandelion, or apically from an axis, as on many palms.
rostellate: Having a short beak.
rostellum: A little beak: a slender extension from the upper edge of the stigma in orchids.
rosula: A rosette.
rosulate: In the form of a rosette.
rot: Any of various diseases causing the breakdown and rotting of tissue.
rotary edger and trimmer: A lawn tool which has rotating spikes on one edge to trim grass back from drives and walks.
rotary mower: The most common type of grass-cutting tool, usually powered by gasoline or electricity.
rotate: Describes a corolla that is wheel-shaped flat and circular in outline.
rotation grazing: Alternating between two or more pastures. See also: cell system pasturing, deferred grazing.
rotund: Rounded.
rough: Papillose
rubefacients: Herbal medicines which open the small blood vessels of the skin to increase its heat and redness.
ruderal: Growing in poor land or waste places.
rudimentary: Partially developed.
rufescent (alt. rufous): Reddish-brown.
rugulose: Covered with minute wrinkles.
ruminate: Having a surface which is coarsely wrinkled, appearing as though chewed by a cow and then spit out, but not with the margins appearing gnawed as in erose margins.
runcinate: Sharply incised, with the segments directed backward.
runner: A filiform or very slender stolon. A prostrate branch that roots at its joints.
runoff (alt. run-off): Water which originated on top of the land, such as rain, and collected beyond the ability of the soil to absorb it, so it flows away.
rush (pl. rushes): Any of various monocotyledonous, grass-like, often tufted marsh plants of the family Juncaceae, having cylindrical often hollow stems.
rust: A large fungus group infecting such plants as roses and snapdragons. Round spots occur on the leaves, filled with yellow or reddish spores.
rusticate (n. rustication): To build or face with usually rough-surfaced masonry.
saccate: Sac-shaped.
sagittate: Shaped like an arrow-head, the basal lobes directed downward.
salinity: Refers to an excess of salts in the soil which causes leaves to scorch and turn yellow and does great harm to many plants.
salver-shaped: Describes a corolla that has a slender tube abruptly expanded into a flat limb.
salverform: Having a slender tube which expands abruptly.
samara: A dry, one-seeded, indehiscent winged fruit; a key.
samaroid: Resembles a samara, a winged fruit.
sandbar (alt. sand bar): A temporary ridge of sand formed by currents in a body of water.
saponin: A glycoside compound of plants which has a foaming or soap-like action.
saprophyte: A plant lacking chlorophyll and living on dead organic matter.
saprophytic: Feeding from dissolved or decayed organic material, as a saprophyte.
sapwood: The more recently produced, outer layer of wood tissue of a tree, usually lighter in color than the heartwood.
sarmentose: With long slender stolons.
saturation cratering: Ancient land around a volcanic area, filled with old and new craters from repeated eruptions.
savanna (alt. savannah): A flat grassland of tropical and subtropical regions usually having distinct periods of dry and wet weather.
saxatile (alt. saxicolous, alt. saxicoline): Growing among or upon rocks.
scaberulous: Slightly scabrous.
scabrid: Minutely rough.
scabridulous: Slightly rough.
scabrous (syn. scabrid): Rough to the touch.
scaffold branches: The main side branches of a tree, especially a fruit tree.
scalariform: Having a ladder-like pattern.
scale: 1. A thin, membrane-like covering of the bud or twig base. A fine, grain-like surface material. 2. Sap-feeding insects that live under shell-like scales on stems, bark, and leaves.
scale leaves: Specialized leaves, including those covering buds or composing bulbs.
scales: The chaff on the stems of ferns.
scaly: Having tiny scales attached at only one end.
scandent: Climbing, but not self-supporting.
scape: A peduncle rising from the ground, naked or without proper foliage, e.g., a dandelion; the leafless stemof a flower.
scapose: Bearing or resembling a scape.
scarify (n. scarification): To scar or nick the seed coat to enhance germination.
scariose: Scarious, having thin, dry, shriveled tissues.
scarious: Thin, dry, and membranaceous, not green.
scarred: Having marks where organs have fallen off, such as leaf scars on stems.
schizocarp: A fruit that splits between carpels into one-seeded portions or lobes.
scientific name (syn. botanical name, syn. technical name): The name applied to a plant, animal, or other organism, according to the Codes of Nomenclature. Although in some cases a scientific name is changed; it is almost always a much more reliable manner of identifying a plant than the often variable common name. See also: binomial.
scion: A cutting from the upper portion of a plant that is grafted onto the rootstock of another plant, usually a related species.
scion rooting: Covering a low graft with soil so that the plant develops roots directly from both the rootstock and the scion.
scion wood: Shoots from which graft scions are cut.
sclereid: A variably shaped sclerenchymatous cell of a higher plant.
sclerenchyma (adj. sclerenchymatous): Tissue composed of cells with thickened and hardened walls.
scleromorph: A plant with leaves and/or stems that are hard, usually having a thick cuticle. See also: xeromorph.
sclerophyll: A woody plant with small, leathery, evergreen leaves and generally found in hot, dry climates. See also: chaparral, fynbos.
sclerophyllous: Having leaves stiffened by sclerenchyma.
sclerotium: A dense mass of filaments comprising the dormant phase of certain fungi.
scoop shovel: A shovel with a very large blade, often made of thin light-weight metal or plastic, used for moving large amounts of crops such as ear corn, or clearing water.
scorch: The drying and browning of leaf margins usually caused by unfavorable environmental conditions.
scorpioid: Describes an inflorescence that is circinately coiled while in bud.
scrambler: A plant with long stems, often with thorns to help it support itself as it climbs through shrubs.
scree: Fragmented rocks usually found at the base of a cliff or boulder where the action of wind and water has broken the particles loose. Scree may be used in gardens as a mulch.
screen: A single plant or grouping of plants used to bar certain parts of the landscape from view.
scuffle hoe: A medium-weight hoe with the blade fastened to the handle in the middle of the horizontal blade, allowing it to be pushed and pulled, cutting weeds on each direction.
scutate (alt. scutellate): Platter-shaped, with a flat center and raised margins, as a water lily leaf, Nymphaea lotus.
scutelliform: Shaped like a small shield.
scythe: A long-handled blade for making grass into hay; the term is sometimes used for the blade without the handle. See also: snath.
seawater: Ocean water with a high salt content.
secateur: Hand-held pruning shears.
secondary species: The species subordinate to the dominant species, like dogwood, Cornus, in an oak, Quercus, forest.
sectio (alt. section): The category of supplemental taxa at a rank between subgenus and series.
secund: Twisted or turned to one side.
sedatives: Medicines which can slow certain bodily functions and promote sleep.
sedge: Any of the grass-like, monocotyledonous plants of the family Cyperaceae, having achenes and solidstems wich are triangular in cross-section.
seed: The ripened ovule, consisting of the embryo and its proper coats.
seed coat: The outer protective covering of a seed.
seed drill: 1. A shallow trench in which to sow seeds. 2. An implement for planting seeds.
seed fern: Extinct fern-like plants that bore seeds on the frond.
seed leaf: A cotyledon.
seed lot: Seeds of a particular crop gathered at one time and likely to have similar germination rates and other characteristics.
seedbank: A facility designed for the ex situ conservation of individual species and varieties through controlled seed storage.
seedbed: An area cultivated for planting seeds.
seedhead: The dry fruit containing rip seeds.
seedling: A young plant grown from a seed.
segment: 1. One of the parts of a leaf or other like organ that is cleft or divided.
segregate: 1. A new genus culled from an established one for taxonomic reasons. 2. A hybrid which exhibits the genetics of one of the parents more clearly than those of the other parent.
seiche: A rapid and sometimes violent fluctuation in water level within a landlocked body of water, usually due to sudden changes in barometric pressure, the ripples lasting from minutes to several hours. See also: tsunami.
selection: A distinct form of a plant, sexual or asexual in origin, selected and propagated for monetary reasons or beauty, and named as a cultivar.
selective felling (syn. selective cutting): When only choice trees are cut in a forest.
self: Having a single pure color with no markings.
self-clinging: Refers to plants which climb rocks or structures without the support of other plants, perhaps by suckers or tendrils.
self-fertile: Able to be pollinated by its own flowers.
self-pollination: The transfer of pollen from the anther of a flower to the stigma of the same flower, or to different flowers on the same plant.
self-seeding: Produces offspring from seed without intervention.
self-sowing: Produces offspring from seed without intervention.
semelparity: Refers to an organism that has a single reproductive season and then dies. See also: iteroparity.
semi-: Prefix meaning half or partly.
semidouble (alt. semi-double): Having more than the usual number of petals but with at least some pollen-producing stamens.
semievergreen (alt. semievergreen): Retaining at least some green foliage well into winter, or shedding leaves only in cold climates.
semihardwood cutting: A cutting taken from a stem that has just begun to develop woody tissue, for the purpose of propagation.
semihardy: Questionably hardy in a given temperature zone; susceptible to damage by extreme cold or heat.
semirotate: Saucer-shaped, almost flat.
semiterete: Refers to a cylinder which is rounded on one side, but flat on the other, as some leaf petioles.
senescence: The process of aging in a plant or plant part (as a leaf) from full maturity to death.
senescent: Dying of tissues following maturity.
sensu: Meaning "in the sense of" in taxonomy.
sepal: A division of a calyx; one of the outermost circles of modified leaves surrounding the reproductive organs.
sepaline: Refers to sepals.
sepaloid: Like a sepal.
sept: A small dent or cavity.
septate: Divided by partitions.
septicidal: Describes a capsule that is dehiscing through the partitions and between the cells.
septifragal: Describes the dehiscence of a fruit where the valves or backs of the carpels break away leaving the septa intact.
septum (pl. septa): Any kind of partition.
sere: The complete cycle of changes from the original state to the climax condition, e.g., oak-maple forest, forest destroyed by fire, meadow, brushland, young mixed conifer-deciduous forest, oak-maple forest.
seriate: In a whorl or row, generally preceded by a number or numerical prefix, as triseriate meaning in three rows.
sericeous: Bearing fine, usually straight, appressed, hairs.
series: A group of similar, but not identical, plants.
serotinal: Appearing in the autumn or late summer.
serrate: Having sharp teeth pointing forward.
serrulate: Finely serrate.
sessile: Without footstalk of any kind.
set: 1. The development of fruit, and or seed, following pollination; to set seed. 2. To transplant as seedlings. 3. To apply as a graft. 4. A young bulb, tuber, or other type of vegetative propagule ready for planting. 5. Transformation of cement paste or concrete from a fluid-like consistency to a stiff mass.
set seed (alt. go to seed): To produce seeds after flowering. In some cases a gardener wishes to prevent this in an effort to prolong flowering, or continue harvesting the foliage of an herb.
seta: 1. A bristle. 2. In mosses, the stalk holding the spore capsule.
setaceous: Bristle-like.
setiform: Bristle-shaped.
setose: Beset with bristles.
setulose: Having minute bristles.
sextant: An instrument used mostly at sea, where there are no bench marks, to determine location by latitude and longitude.
shade (adj. shady): Light diminished by some blocking feature. See also: light shade.
shade tree: A larger tree planted in a location where the canopy provides shade at ground level.
sharp sand: Coarse sand used to loosen heavy soil and in construction, as opposed to the more finer grained play sand.
sharp-pointed: Acute, mucronate, pungent.
sheath: A tubular envelope, as the lower part of the leaf in grasses.
sheathing: Enclosing as by a sheath.
shoot: A young, actively growing twig or stem.
short-lived: Describes a plant, usually perennial, where the individuals live for only a few seasons.
shovel: 1. A long-handled scoop-like implement used for digging, lifting, and throwing, etc. 2. The quantity contained in one scoop.
shrub: A woody perennial, smaller than a tree, usually with several stems.
shrublet: A dwarf woody plant.
sialagogues: Herbal medicines that can increase the flow of saliva.
sickle: 1. A short-handled hand tool similar to a scythe but smaller and curved into a semicircle, used to cut heavier crops like corn, Zea mays.
sickle bar: A mechanical cutting tool that fastens onto a tractor's power source.
sigmoid: Curved like the letter S.
siliceous: Containing silica.
silicle (alt. silicula, alt. silicule): A short silique, no more than twice as long as it is broad.
silique (syn. siliqua): A dry, dehiscent, elongated fruit formed from a superior ovary of two carpels, with two parietalplacentas and divided into two loculi by a false septum between the placentas, occurring in plants of the family Cruciferae.
silky: Covered with close-pressed soft and straight pubescence.
silt: Fine-grained sediment usually 1/20 millimeter or less in diameter, finer than sand particles and coarser then those composing clay.
silt load: The particles finer than sand which are carried in a suspended state in moving water. See also: bed load.
silviculture: The cultivation and care of forest trees.
simple: Of one piece; not compound.
simple fruit: A fruit developed from a single ovary.
simple leaf: A leaf with an undivided blade.
single: 1. A single flower. 2. Describes varieties having only one bloom per stem.
single flower: A plant containing the normal number of petals. Double flowers often have multiples of the normal number: 6 or 9 for three-petal flowers, 8 or 12 for four-petals flowers, etc.
single-worked: Grafted only once so that the grafted plant consists of rootstock and scion.
sinuate: With the outline of the margin strongly wavy.
sinuous: Wavy like the path of a snake.
sinus: The cleft or recess between two lobes.
skeletonized: Refers to a leaf which has only ribs and veins left, the soft tissue having been consumed by insects or bacteria.
skeletonizer: Any of various lepidopterous larvae that eat the parenchyma of leaves reducing them to a skeleton of veins.
skylight: The diffuse and reflected light of the sky. See also: direct sunlight.
sludge: Precipitate of solids from water or sewage treatment, which may or may not contain harmful compounds; generally composted for a year or two before applying as organic fertilizer.
slump test: A test used to determine workability of cement or concrete.
small fruits: Those species which produce edible fruits, but do not grow on trees, e.g., strawberries and blueberries.
smoke jumper: A trained firefighter who is dropped from an airplane in the path of a wildfire to attempt to control the blaze.
smooth: Without roughness or pubescence.
snag: 1. Part of the rootstock left during a graft to hold the scion in place. 2. Removal of the projection when the scion no longer needs it. 3. A rough projection on a woody plant which needs to be removed.
snath: The handle of a scythe.
snow fencing: Wooden or plastic lath joined by wire into long rolls, then erected 100 feet (33 m.) or so on the windward side of a road or barnyard. The lath breaks the velocity of the wind allowing snow particles to drop before reaching the road. It may also be used as a shade cover for plants.
sobole: A shoot, especially from the ground.
soboliferous: Bearing soboles.
social dominance: The control of behavior of those animals lower in the hierarchy, by aggression, intelligence, or other factors of the alpha animals.
social facilitation: The effect of the closeness of one organism upon the conduct of another one.
sod coring tool: A lawn tool which removes spikes of soil, about one half inch (1 cm) in diameter, to allow air and water to penentrate. See also: aerator.
sod planter: A lawn tool which cuts a hole of about 2 inches (5 cm.), releases the core with a hand or foot system, picks up a new sod block and inserts it.
sodic: Of, relating to, or containing sodium.
softwood: The immature stems of woody plants. Also, term applied to conifers as opposed to the broad-leavedtrees, or hardwoods.
softwood cutting: A cutting taken from a green or immature stem of a woody plant, for the purpose of propagation.
soil: 1. The top layer of the earth's surface, consisting primarily of clay, sand, silt, and organic matter. 2. Any natural or synthetic substance or medium in which plants may take root and grow.
soil amendment: Substance added to soil to increase its nutritive value, friability, moisture retention, or some other aspect.
soil cuber (alt. soil blocker): Hand-held device into which moist soil is packed, then released in the form of a cube or block in which a single seed is planted.
soil fixation: The conversion of a soluble substance such as phosphorus from the exchangeable form useful to plants, to a relatively insoluble form.
soil sampler: A hollow tube with a T handle, which is pressed into the soil to get a core of the horizon.
soilless mix: A potting soil that uses sand, bark, and/or other ingredients, but not any actual soil.
solid: Smoothly pithy, the twig center neither chambered nor hollow.
solitary: Borne singly or alone; not in clusters.
solutio (abr. sol): Latin term for a solution.
somatic: Belonging to the vegetative part of a plant as opposed to the reproductive.
soralium (pl. soralia): A clump of soredia.
soredium (pl. soredia): A microscopic clump of agal cells surrounded by the hyphae of fungi and erupting at the surface of the thallus.
sorus (pl. sori): An assemblage of sporangia; a fruit dot.
spacing: Measured distance between the center of one plant and the center of the next closest ones.
spade: A digging implement, foot powered, usually of heavier construction than a shovel and often with a flat end.
spadix: A flower spike with a fleshy axis, usually enclosed in a spathe.
spartoid: Rush-like, but sharp and rigid.
spasmolytic: Describes an herbal preparation that can ease cramps or spasms.
spathaceous: Resembling or having a spathe.
spathe: A sheathing bract or pair of bracts partly enclosing an inflorescence and especially a spadix on the same axis.
spatheole: A small or secondary spathe.
spathiform: Shaped like a spathe.
spatulate (alt. spathulate): Gradually narrowing downward from a rounded summit; spoon-shaped.
species (abr. sp., pl. spp.): A fundamental category of taxonomic classification that ranks below a genus and above subspecies; a population or series of populations whose individuals have the potential to freely breed with one another and that is discontinuous in variation from other populations or series of populations. The plural abreviation "spp." is usually used to refer to all the individual species within a genus, e.g., Cornusspp. refers to all the plants within the dogwood genus.
species diversity: Almost the same as species richness, but in more technical literature, an ecosystem that is said to be more diverse if the species present have equal population sizes and less diverse if many species are rare and some are very common.
species richness: The number of species within a region. See also: species diversity.
specimen (pl. specimens): 1. Item considered typical of its class, e.g., an herbarium specimen. 2. Plant grown for landscape exhibition, e.g., a specimen tree.
specimen preparation: The collection, selection, arrangement, pressing, drying, and mounting of a plant for an herbariumspecimen, allowing many specimens to be stored in minimal space.
specimen tree: A tree placed so people can gain the greatest enjoyment for the color, texture, scent, or other pleasures it provides.
spermatium (pl. spermatia): The nonmotile male cell of red seaweeds; also used for similar cells in fungi.
spermatocyte: A cell which gives rise to sperm cells.
Spermatophyta: A major taxonomic division containing all plants which reproduce by seed, subdivided into Gymnospermae and Angiospermae.
spermatophyte (syn. seed plant): Any plant of the division Spermatophyta, the higher plants that produce seeds, including the gymnosperms and angiosperms.
spermatozoid: A motile ciliated male reproductive cell.
sphagnum moss: Bog mosses that are often used as soil additives and packing material because of their ability to retain moisture. See also: peat moss.
spherical: Nearly round.
spicate: Arranged in or resembling a spike.
spiciform: Spike-like.
spiculate: Having fine fleshy points.
spider mite (syn. red spider): Any of several small, red, web-spinning mites of the family Tetranychidae that feed on and damage leaves.
spike: A form of simple inflorescence with the flowers sessile or nearly so upon a more or less elongatedcommon axis.
spike harrows: A field implement with spikes that breaks up clods and levels soil.
spikelet (syn. earlet): A small or secondary spike, most often refiring to those forming the inflorescence of grasses.
spindle-shaped: Same as fusiform.
spine: A sharp woody or rigid outgrowth from a stem, leaf, or other plant part.
spinescent: 1. Having spines. 2. Terminating in a spine. 3. Modified to form a spine.
spinose: Spine-like, or having spines.
spinulate: Having spinules.
spinule: A minute spine or spine-like process.
spinulose: Thorny; set with small spines.
spired: Having a crown with several points.
splitting maul: An axe with a broad, heavy head, shaped into a wide nonstick wedge.
spoils: Soil from stream or drain bottoms dredged out when the channel was made deeper.
sporangiophore: A specialized stalk bearing a sporangium.
sporangium (pl. sporangia): A tiny globe in which the spores are produced; often applied to the capsule, but by some authorsrestricted to the spore sac, or inner sac of the capsule containing the spores.
spore: The reproductive organ in cryptogams which in function corresponds to a seed but possesses no embryo.
sporecase: Same as sporangium; the case in which the spores are borne.
sporocarp: The fruit cases of certain cryptogams containing sporangia or spores.
sporogenesis: Reproduction by means of spores.
sporogenous: Describes cells or tissues in which spores are formed.
sporophyll: A leaf bearing spores.
sporophyte (syn. sporophore): 1. The spore-bearing part or generation. In mosses, it consists of the seta and capsule and constitutes the so-called fruit. In ferns, the conspicuous plants that bear spores.
spororogonium: The sporophyte or spore-bearing part of the moss.
sport: An abrupt, naturally occurring genetic change resulting in a branch that differs in appearance from the rest of the plant, or, a plant derived by propagation from such a genetically changed branch.
spreader: 1. A lawn cart that applies seed, fertilizer, etc. 2. A large wagon used on organic farms to apply manureto the fields.
spreading: Having a horizontally branching habit.
sprig: A small part of a plant, such as stolons used for propagations, twigs bearing flowers, etc.
spring wood: Wood which is formed during the period of rapid growth in the spring, appearing lighter in color than the wood formed later as the growth slows down.
spud (alt. ice spud): A tool shaped like a flat-ended oar that is used to chop a hole through ice for fishing or studying underwater biology, but which may also be used to clear ice from sidewalks, cut sod or roots, edgesidewalks, etc.
spur: A hollow sac-like or tubular extension of some part of a blossom, usually nectariferous. Also, a short, slow-growing branchlet.
spur branch: A stubby branchlet with densely crowded leaves and leaf scars.
spurred: Calcarate; refers to a flower with tubular projections from the petals or sepals, usually with nectarglands.
sqarulose: Diminutively squarrose.
squamate (alt. squamose, alt. squamous): Covered with scales.
squamulate: Having squamules.
squamulose: Having small scales.
squarrose: Turned back at a right angle or more sharply, as the tip of a phyllary.
stability: Resistance to variation in populations and disturbances, resulting in the persistence of communitycomposition over long periods of time.
staddle: A foundation of trunk and main branches, either of rootstock or stembuilder, for grafting.
staking: Providing support for newly-planted trees or tall plants by tying the plant to one or more stakes planted beside and parallel to the plant.
stalk: A short, supporting axis.
stalked: Joined to an axis with a stalk.
stamen: One of the male, pollen-bearing organs of the flower.
staminal: Attached to or referring to the stamen.
staminate: With stamens and without pistils.
staminode (syn. staminodium, syn. staminoide): A sterile stamen, or any structure without anther corresponding to a stamen.
staminoid: A pollenless stamen.
standard (syn. banner): 1. A plant with a strong vertical stem, particularly one that would not normally grow that way; a vine or shrub trained as a tree with a single trunk and a more or less spherical top. 2. Uppermost, usually erect, petals of some flowers; the upper dilated petal of a papilionaceous corolla.
stegocarpous: Having the capsule operculate.
stele: The axial vascular and associated tissues from the endodermis inward.
stellate (syn. stelliform): Star-shaped.
stem: The main ascending axis of a plant.
stembuilder: A variety of woody plants used in a graft as intermediate stem piece to provide a strong trunk for standard trees, or to introduce resistance to disease or winter injury.
steppe: A vast arid, usually level and grassland, particularly those of southeastern Europe and Asia and generally having extreme variations in temperature. See also: pampas, prairie.
stereids: The small thick-walled cells seen in.
sterigma (pl. sterigmata): The spike on which a fungus spore is home.
sterigmata: The small woody stem to which the leaves of spruces and hemlocks are attached.
sterile: 1. Barren. Refers to fern leaves that do not produce spores. 2. Unproductive, as a flower without a pistil, or a stamen without an anther.
stichidium: A small structure (lobe or branch) bearing tetrasporangia.
stigma: That part of a pistil through which fertilization by the pollen is affected.
stigmatic: Belonging to or characteristic of the stigma.
stigmatose: With conspicuous stamens.
stigonema: A filamentous blue-green algae.
stilt-roots: Adventitious support roots.
stimulants: Herbal medicines that can increase the energy or activity of a tissue, organ, etc.
stipel: A stipule of a leaflet.
stipellate: Having stipels.
stipitate: Having a stipe or short stem.
stipular: Belonging to stipules.
stipulate: Having stipules.
stipule: An appendage at the base of a petiole, often appearing in pairs, one on each side, as found on roses.
stipule scar: The scar left on a twig by the fall of a stipule.
stock driveway: A lane; a strip of land designated for the movement of livestock.
stock plants: Mother plants kept for cuttings to reproduce the plant.
stoloniferous: Producing stolons.
stoloniferous stem: A slender creeping stem with minute leaves.
stoloniform: Like a stolon, underground stem.
stoma (pl. stomata): 1. An orifice in the epidermis of a leaf communicating with internal air cavities. 2. A pore in the wall of a capsule surrounded by special guard-cells and serving the same purpose as the stomata in the epidermis of the leaves of flowering plants.
stone (alt. stone fruit): The single seed of a drupe, surrounded by a large, hard shell and covered by pulp.
stool: Clump of shoots growing from near the ground.
stooling: Cutting down to ground level to induce tightly packed new growth.
stopping: Pinching off the terminal bud to induce branching.
storm surge: Before and during a storm, an abnormal and rapid rise in lake level along the shore, caused mostly by strong onshore winds and changes of atmospheric pressure.
stove: A heated greenhouse.
straggling: Semiupright.
straight: Describing ray florets having little or no curvature throughout their length (used in describing dahlias.)
strain: A number of plants which have similar characteristics such as color blends, different enough to be designated, but not sufficiently distinct to be considered a horticultural variety.
stramineous: Straw-colored.
strand: 1. The area of lakeshore above the waterline that is subject to the action of wind and rain. 2. On ocean beaches, the area between high and low tidal marks.
stratified: Having prominent horizontal layers.
stratify (n. stratification): Artificially overcoming a seed's dormancy by placing them in layers of moisture-retaining media and keeping them under generally cool and moist conditions for a period of time, so as to simulate winter conditions.
strawflowers: Species of plants which easily become dried flowers.
stria (pl. striae): A thin ridge or groove.
striate (syn. striated): Marked with fine, longitudinal lines or ridges.
strict: Very straight and upright.
strigose: Beset with appressed sharp straight and stiff hairs.
strigulose: Minutely strigose.
string tags: Waterproof tags used to mark collected specimens for herbarium study.
striolated: With delicate lines or ridges.
strip cropping: A method of planting a crop in parallel bands following the contours of the slope; this lessens erosion. See also: field strip cropping, filter strip.
strobiloid (alt. strobiliform): Cone-shaped.
strobilus (alt. strobile): 1. Woody cone, as in Gymnospermae. 2. A cone-shaped inflorescence marked by imbricatedsporophylls. 3. A dense cone-like structure producing spores.
stroma: 1. A compact mass of fungal hyphae producing perithecia or pycnidia. 2. The colorless proteinaceousmatrix of a chloroplast in which the chlorophyll-containing lamellae are embedded.
strone (alt. stron): A hill that terminates a ridge; the end of a ridge.
strophile: An appendage at the hilum of certain seeds.
strophiole: Resulting from an inverted ovary that has fusion of the nucellus and funiculus. The strophiole is a small swelling on a ridge.
struma: A goiter-like swelling on one side at the base of the capsule.
strumose: Having a struma.
stunt virus: A type of virus disease which stops the growth of a plant.
stylar (alt. styled): Either having styles or found on a style.
style: The usually attenuated portion of the pistil connecting the stigma and ovary.
stylopodium: A disc-shaped enlargement found at the base of the style in some Umbelliferae.
styptic: A medicine to stop minor surface bleeding, e.g., razor cuts.
sub-: A prefix meaning somewhat or physically below.
subarctic: Of, relating to, or being the regions bordering on the arctic zone.
suberect: Ascending toward the edges.
suberin: A complex fatty substance found especially in the cell walls of cork.
suberization (adj. suberized): The conversion of the cell walls into corky tissue, called suberin.
suberous: Cork-like.
subgenus: An intermediate category in taxonomy between genus and species.
subimbricate: Somewhat overlapped; slightly shingled.
submergent vegetation: Plants with stems and leaves below water level, sometimes with reproductive parts above water.
submersed (alt. submerged): Underwater.
subopposite: Almost opposite but one leaf or leaflet of each pair a little above the other.
subsessile: With a slight stalk.
subshrub: A plant with more or less woody branches and roots, less woody than a true shrub, but more woody than a perennial herbaceous plant; a small shrub, woody only at the base.
subspecies (abr. ssp.): The rank of taxa below species but above variety; a subdivision of a species whose members have certain hereditary characteristics distinct from other populations of that species. A subspecies is added to the specific binomial and preceded by "ssp.", such as obtusifolia in the epithet Grevillea thelemannianassp. obtusifolia.
substratum (syn. substrate): The material on which a plant grows.
subtend: To be just below and close up to or enclosed in its axil.
subterranean: Below ground.
subtropical (syn. semitropical): Of, relating to, or being the regions bordering on the tropical zone.
succession (syn. biotic succession): 1. The development of a plant community from its initial stage to its climax stage; usually from one consisting of grasses and forbs to one of shrubs and, finally, to forest. However, depending on the climate, the climax stage may consist of a prairie, savana, or any number of other ecosystems. 2. The changes in the species composition of communities following a natural or human disturbance like the natural filling of a pond or the clearing of a road through a forest.
succulent: A plant having fleshy stems or leaves, often adapted to xeric conditions.
sucker: A shoot from the root or lower part of a stem. In roses, a young cane emerging below the bud union and therefore representing the variety of the understock rather than the top variety. A shoot appearing on a tree limb is called a water sprout.
suffrutescent: Slightly or obscurely shrubby.
suffruticose: Very low and woody; diminutively shrubby.
sulcate: Grooved or furrowed.
summer wood: Wood produced late in the growing season when growth is slow.
sunken garden: A garden recessed into the ground to create a secluded atmosphere or to facilitate a view down onto a feature such as a knot garden.
super- (alt. supra-): A prefix meaning above, greater than, superior to.
superficial: On the surface.
superior ovary: With the flower parts growing from below the ovary.
superparasitism: Parasitization of a host by more than one individual, usually of a single species.
superphosphate: A fertilizer with a very high amount of phosphates, uusally 30-45 percent, and most often used to promote flowering in ornamental plants.
superposed: Accessory buds which occur above the axillary buds.
supersaturation: The uptake of unusual amounts of water by a plant; this can cause plant specimens to mold rather than dry.
supersporangium: A structure containing tetrasporangia and acting as a sporangium.
supra-axillary: Borne above the axil.
suprabasal: Above the base, usually referring to pinnae or pinnules.
supramedial: Beyond the middle.
surculose: Producing suckers.
suspended: Describes an ovule that is hanging from the apex of the cell.
swale: A wet depression between beach ridges, fed by ground water and runoff, rarely influenced by changes in water level.
swell: A huge natural dome structure where movement of the earth's crust has raised stratigraphic layers in mounds rather than breaking them with a fault. Erosion exposes the oldest layers in the middle with subsequent layers surrounding it in concentric circles.
symbiosis (adj. symbiotic): The living together of different species of organism which may or may not be to their mutual benefit. See also: mutualism, parasitism.
symmetrical: Describes a flower that can be divided into similar halves.
sympatric: Describes two or more closely-related species having coincident or overlapping ranges of distributionbut not interbreeding. See also: allopatric.
sympodium (pl. sympodia, adj. sympodial): A primary axis without a single, persistent growing point that develops from a series of lateral branches which change direction in succession and give it a zigzag form, as occurs with orchids of the genusCattleya. See also: monopodium.
syncarp: An aggregate or multiple fruit produced from fused or coherent pistils, the small individual fruitsmassing and growing together into a single fruit, coalescent.
syncarpous: With the carpels of the gynoecium united in a compound ovary.
syncline: A geological structure that appears when strata fold downward toward a common line.
synoicous (alt. synaecious): Having the male and the female organs mixed together in the same cluster.
synonym (abr. syn.): Any one of two or more names used for the same taxon rank; a rejected name due to misapplication or difference in taxonomic judgment. See also: basionym, homonym, tautonym, autonym, taxonomic synonym, nomenclatural synonym.
syntype: Any one of two or more specimens cited by the author when no holotype was designated, or when two or more were designated. See also: holotype, lectotype, neotype, isotype, nomenclatural type, topotype.
systematics: The study of the evolutionary and genetic relationships among organisms and of their phenotypesimilarities and differences.
tautonym: An illegitimate binomial in which the genus and species are the same word, such as Amoracia armoracia, later changed to Armoracia rusticana. See also: basionym, homonym, synonym, autonym.
taxon (pl. taxa): A group of genetically similar organisms that are classified together as a species, genus, family, etc.
taxonomic synonym: Any one of two or more different names based on different plant specimens which were later judged to belong to the same taxon.
taxonomy (adj. taxonomic): The classification of organisms based on genetic similarities.
temperature summation: The totality of effective temperatures or day-degrees for a specified period of time, especially the time required for an organism to reach maturity, like a summer. See also: aliquote.
temporal: 1. Refers to the sides of the skull behind the eyes, the temples. 2. Refers to time.
tender: Describes a plant easily killed by frost.
tendril: A clasping, twining, slender outgrowth of the stem that helps support climbing plants.
tension: The stress resulting from elongation.
tepal: A division of the perianth--a sepal or a petal--of a flower in which the calyx and corolla are almost identical in appearances, as occurs in tulips and lilies. In Orchidaceae, this term refers to any sepal or petal, except the labellum.
terete: Having a circular transverse section.
terminal: Apical.
ternate: With three nearly equal divisions.
terrace: The entire outdoor paved surface; the term often refers to the patio only.
terrarium: A small artificial environment for a specified habitat. An aquarium is for a water habitat, usually containing fish and plants. A terrarium generally has a woodland setting, with the emphasis on plants rather than animals.
terrestrial: Growing in soil.
tetraploid: Having twice the normal number of chromosomes.
thallus (pl. thalli): In cryptogams, a cellular expansion taking the place of stem and foliage and forming the main body fungi and lichens.
thatch: A layer of dead grass that does not decay into soil.
thermal stratification: The successive horizontal layers of a body of water having different temperatures, each layer more or less sharply different from the adjoining ones, with the warmest at the top. See also: thermocline, epilimnion, turnover.
thermocline: In bodies of water, there are normally stratified layers of decreasing temperature with increased depth. Thermocline is the layer where the temperature starts to decrease rapidly, about one degree centigrade or more with each meter (3 feet) of depth. See also: epilimnion, thermal stratification.
thorn: A stout, sharp, woody outgrowth of the stem or branch.
throat: The orifice of a gamopetalous corolla or calyx; the part between the proper tube and the limb.
tier: A radial, layered branching habit of excurrent trees.
till: Mixed deposits of gravel, boulders, sand, and other materials that were carried by a glacier.
timber: Standing trees, felled trees, or seasoned logs. See also: lumber, pulpwood.
timber cruising (timber cruiser): The process of surveying forest land with the objective of predicting how many board feet of lumberthe plot will yield.
tip: The apex.
tip layering: A propagative method similar to air layering, except a flexible branch such as blackberry, Rubus, is bent to the ground and buried in moist soil or a mixture of peat moss and sand, instead of being wrapped on the upright stem.
tissue culture: The growth of small pieces of plant tissue (usually the meristem) under sterile conditions in artificial media.
tooth: 1. The processes comprising the fringe around a peristome. 2. The smallest division of a frond.
toothed: Having the margin shallowly divided into small, tooth-like segments.
top variety: The variety bud-grafted to the understock, and thus the variety that flowers.
topography: The configuration of a surface including its relief and the position of its natural and man-made features.
topotype: A specimen collected later from the original type locality, or from the area from which the type was described. See also: holotype, lectotype, neotype, isotype, nomenclatural type, syntype.
torus: The receptacle of a flower.
trailing: Lying prostrate on the surface or on other vegetation.
translucent: Thin enough to transmit light, but not a concrete image.
transparent: Thin enough to transmit an image.
transpiration: The passage of water through a land plant and usually out the pores of its leaves.
transplant: To move a plant from one place to another.
transverse: Cross-wise in position.
tree: A woody, self-supporting perennial plant usually with a single main stem and generally growing more than 20 feet tall.
tree line (alt. tree limit, timberline): The height above which trees can no longer survive on a mountainside, or the northern or southern limit beyond which only stunted forms appear on a continent toward a pole.
trench: A long cut, ditch, channel, especially man-made.
tri-: A prefix meaning three.
triangular: Having the outline of a triangle.
trimerous: Having flower parts, such as petals, sepals, and stamens, in groups of three.
tropical: Of, being, or characteristic of a region or climate that is frost-free with temperatures high enough to support year-round plant growth.
true leaf: A leaf typical of a plant that appears subsequent to the cotyledons.
trunk: The major woody stem of a tree.
tuber: A thickened and short subterranean branch having numerous buds or eyes and used for food storage.
tubercle: A small tuber or tuber-like (not necessarily subterranean) body.
tubular: With the petals partly united to form a tube.
tundra: The vegetation type of very cold climates overlying permafrost and consisting of lichens, sedges, mosses, grasses, and low woody plants.
turbinate: Top-shaped; inversely conical.
turnover (syn. overturn, syn. fall overturn): The cycling of upper and lower strata of water in bodies of fresh water in autumn, and vice versa in spring, caused by the heating or cooling of upper surfaces. When the upper surface is cooler than the lower water, the cool water sinks.
twig: The end subdivision of a branch; a young shoot, generally applied to the growth of the past season.
twining: Clasping by winding around.
twisted: The seta of many mosses twists strongly in drying. If the twist is such as would be made by seizing the capsule and twisting it to the right, it is said to be twisted to the right. It is possible that this twisting of the seta aids in scattering the spores.
type: One of several categories of herbarium specimens, chosen by taxonomists as being close or identical to that chosen by the original author.
ultimate: Of the lowest order; the smallest division.
umbel: An inflorescence in which the peduncles or pedicels of a cluster spring from the same point.
umbellet: A secondary umbel.
underdrainage: 1. The placement of perforated plastic pipe or porous clay pipe underground, often with a layer of crushed stone over it, to carry away excess water. 2. A natural or man-made system allowing excess water to be carried away from a cultivated field.
understock (syn. rhizome, syn. rootstock): The stock or root plant onto which a shoot has been grafted to produce a new plant in bud-grafting, especially in cases of double-worked trees.
understory: The shrubs and smaller trees between the forest canopy and the ground cover.
undifferentiated: Describes parts or tissues which are very difficult to tell apart, like the tepals of tulips, Tulipa.
unicellular: Made of one cell.
uniform: Always having the same shape, as opposed to dimorphous.
union: A graft.
unisexual: A flower of one sex only, either pistillate (female) or staminate (male).
united: Fused together.
unstratified: Lacking distinct layers.
vacuole: A cavity or vesicle in the cytoplasm of a cell usually containing fluid.
vale: A small valley.
valve: One of the pieces into which a dehiscing capsule splits.
vane: One leaf of a windmill or pinwheel.
variegated: Marked, striped, or blotched with some color in addition to the plant's general overall color.
variety (alt. varietas, abr. var.): The rank of taxa below subspecies but above forma; a plant which retains most of the characteristics of the species, but differs in some way such as flower or leaf color, size of mature plant, etc. A variety is added to the specific binomial and preceded by "var.", such as saxatilis in the epithet Juniperus communisvar. saxatilis.
vascular: Furnished with vessels or ducts.
vegetational analysis: Any of various methods of studying small areas of constituent plants, often counting the numbers of plants of communities, to make extrapolations to a larger area. See also: belt transect, basal area, vegetational cover, timber cruising.
veil: The calyptra.
vein: The thread of fibro-vascular tissue in a leaf or other organ, especially those which branch (as distinguished from nerves).
veinlet: A subdivision or branch of a vein.
veld (alt. veldt): A term commonly used in South Africa for open country occupied by grasslands in higher elevations and scrub or savanna at lower elevations.
venation (syn. nervation): The manner in which the veins are arranged in the leaf.
ventral: Belonging to the anterior or inner face of an organ; the opposite of dorsal.
verge: Border, limit, or boundary; a berm.
vernal: Appearing in spring.
vernation: The arrangement of leaves in the bud.
very double: Roses with a great many petals.
vesicle: A small bladder or air-cavity.
vessel: A row of lignified water-conducting cells rendered continuous by the absorption of the crosswalls.
viable: Describes a seed that is capable of germinating.
vicariation: The occurrence of ecological equivalents replacing each other in similar habitats in different geographic areas, e.g., caribou in North America and reindeer in Eurasia.
vine: A plant that trails, clings, or twines, and requires support to grow vertically.
viscous: Not free-flowing; having the consistency of syrup.
vouchering: Furnishing proof, supporting a claim, as of taxonomic study.
Wardian case: A case of glass sides and top used to maintain the humidity necessary for growing tropical and subtropical plants in temperate region buildings. A popular feature of Victorian homes, used often to display ferns.
water sprout: A sucker produced on the trunk, stem, or large branch of a plant, particularly fruit trees, usually growing straight and at a right angle to the axis. These rapidly growing suckers are generally removed to allow a more open tree and to provide better nutrition to the fruit.
watershed: The complete area from which runoff drains to feed a stream or body of water.
wavy: See also: undulate.
weed: A plant growing where it is not wanted, often to the detriment of a crop or the disfigurement of a landscape design.
wetland: An area where saturation or repeated inundation of water is the determining factor in the nature of the soils, as well as the plants and animals living there. Included in the term are marshes, swamps, bogs, fens, bay heads, wet meadows, potholes, sloughs, bayous, river flood plains, estuaries, and lake margins.
whole: Having all its proper parts or components, often describing a flower.
whorl (adj. whorled): An arrangement of leaves, petals, sepals, etc., in a circle around the stem.
wildfire: A fire that is out of control, such as a forest fire or a burn through a grassland, often threatening houses or farms.
wildflower: A flowering plant growing and usually propagating itself outside of cultivation. Often, but not always, refers to plants native to a region.
windward: The side from which the wind blows. See also: leeward.
wing: 1. A thin, dry, leaf-like membrane found on many fruits, seeds, and leafstalks; any membranous or thin expansion bordering or surrounding an organ. 2. The lateral petal of a papilionaceous corolla.
winged: With projecting thin flat membranes or corky outgrowths.
wood: The hard, fibrous inner tissue of the trunk and branches of a tree or shrub.
woodland (syn. woods): An area primarily covered with trees.
woody: Forming stems that mature to wood.
woody plant: With the stems and limbs containing lignin.
woolly: Clothed with long and tortuous or matted hairs.
xeric: Of, or adapted to, an extremely dry habitat.
xylem: Tissue specialized for the transport of water and minerals upward through the plant.
zygomorphic: Capable of division by only one plane of symmetry.
zygote: The diploid cell formed by the union of two gametes.

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