This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology. For other related terms, see Glossary of phytopathology, Glossary of lichen terms, and List of Latin and Greek words commonly used in systematic names.
A
ab- Prefix meaning "position away from".
abaxial Surface of an organ facing away from the organ's axis, e.g. the lower surface of a lateral organ such as a leaf or petal. Contrast adaxial.
abort To abandon development of a structure or organ.
abscission Natural shedding of an organ that is mature or aged, as of a ripe fruit or an old leaf.
abscission zone Specialized layer of tissue that allows an organ to be shed by abscission when it is ripe or senescent. Such tissue is commonly formed, for example, at the base of a petiole or pedicel.
acaulescent Having no apparent stem, or at least none visible above the ground surface. Examples include some species of Oxalis, Nolina, and Yucca. Antonym: caulescent (possessing stem).
accrescent Increasing in size with age, such as a calyx that continues to grow after the corolla has fallen, e.g. in Physalis peruviana.
accumbent Lying against another part of the plant; when applied to a cotyledon, it means that an edge of the cotyledon lies along the folded radicle in the seed.
-aceae Suffix added to the word stem of a generic name to form the name of a taxonomic family; for example, Rosaceae is the rose family, of which the type genus is Rosa.
achene Dry, one-seeded indehiscent fruit in which the true fruit is not the so-called "berry", but the achenes, which are the so-called "seeds" on the infructescence, e.g. in the genus Fragaria.
acicular Slender or needle-shaped. See also Leaf shape.
acropetal Moving from roots to leaves, e.g. of molecular signals in plants.
acrophyll Regular leaves of a mature plant, produced above the base, as opposed to bathyphyll.
acrostichoid (describing a type of sorus) Covering the entire abaxial surface of a frond, usually densely so, as in Elaphoglossum and Acrostichum.
actino- Prefix that indicates a radial pattern, form, or morphology.
actinodromous (of leaf venation) Palmate or radially arranged venation with three or more primary veins arising at or near the base of the leaf and reaching the margin in most species, but not all.
actinomorphic Regular or radially symmetrical; may be bisected into similar halves in at least two planes. Applies e.g. to steles and flowers in which the perianth segments within each whorl are alike in size and shape. Compare regular. Contrast asymmetrical, irregular, and zygomorphic.
aculeate Armed with prickles, e.g. the stem of a rose.
acumen A long, tapering point, especially the apex of an acuminate leaf.
acuminate Tapering gradually to a point, with concave sides approaching the point. Contrast acute and mucronate. See also Leaf shape.
acute 1. Sharply pointed, but not drawn out, with straight sides approaching the point. Contrast acuminate. See also Leaf shape. 2. Converging at an angle of less than 90°. Contrast obtuse.
ad- Prefix meaning "near or toward"; also meaning "added to".
adaxial Surface of an organ facing toward the organ's axis, e.g. the upper surface of a lateral organ such as a leaf or petal. Contrast abaxial.
adelphia pl. adelphiae A bundle or structure of stamens forming one unit in an adelphous flower; for example, the stamen tube around the pistil of Hibiscus. adelphous Having organs, particularly filaments such as stamens, connected into one or more adelphiae, whether in the form of bunches or tubes, such as is commonly seen in families such as Malvaceae. Usage of the term is not consistent; some authors include closely bunched filaments, while others include only adelphiae in which filaments are connected minimally at their bases. See, for example, Sims: "...the filaments are so closely pressed that they have the appearance of being monadelphous...". Compare derived terms such as monadelphous, having stamens growing in a single bunch or tube, for example in Hibiscus, and diadelphous, growing in two bunches.
adherent Slightly united to an organ of another kind, usually to a part of another whorl, e.g. a sepal connected to a petal. Contrast adnate.
adnate Grown from or closely fused to an organ of a different kind, especially along a margin, e.g. a stamen fused to a petal. Adnate anthers have their halves attached to the filament through most of their length. Contrast connate.
adpressed See appressed
adventitious Produced in an unpredictable or unusual position, e.g. an adventitious bud produced from a stem rather than from the more typical axil of a leaf. Adventitious roots may develop from nodes of prostrate stems of some plant species, or from the hypocotyl rather than from the radicle of a germinating monocotyledon.
adventive Introduced accidentally (usually referring to a weed).
aerial Of the air; growing or borne above the surface of the ground or water.
aestivation Arrangement of sepals and petals or their lobes in an unexpanded flower bud. Contrast vernation.
aff. (affinis) With affinity to others, akin to; often used for a provisionally recognized but unnamed taxon considered close to that name, perhaps a hybrid or extreme variant.
aggregate fruit Cluster of fruits formed from the free carpels of a single flower, e.g. a blackberry. Compare multiple fruit.
agochoric Plants that are spread through accidental transport.
agricultural weed See weed.
agriophyte Plant species that have invaded native vegetation and could survive there without human intervention. They are established there in natural habitats, remaining part of natural vegetation even after human influence has ceased, and are independent of humans in their continued existence.
agrophic Comb-like series of veins forking from a single side of a primary or secondary vein.
agrostology Also graminology. The scientific study of grasses, in the strictest sense only those species which are members of the family Poaceae. Broader usages sometimes also include grass-like or graminoid species from the families Cyperaceae, Juncaceae, and Typhaceae.
alate Having a wing or wings.
albumen Older name for the endosperm of flowering plants. Except for being a storage tissue for nutrients, it is not like the albumen (egg white) of animal embryos.
albuminous (of seeds) Containing endosperm.
-ales Suffix added to the stem of a generic name or descriptive name to form the name of a taxonomic order.
alliant Describes trees that for allied root or canopy ecologies, and also share or benefit from similar and mutual mycorrhizal proliferation. alliant trees root systems often coordinatewith eachother to claim territory in mixed forests and also sometomes share epigenetic information.
alien Any plant introduced to an area outside its natural range. Often used interchangeably or in combination with foreign, exotic, non-native, and non-indigenous.
alkaloid Any of a loosely defined class of organic compounds found in the tissues of many species of plants. Alkaloid molecules have one or more alkaline-reacting nitrogen atoms in their carbon structures. Many alkaloids are commercially important as drugs or poisons, e.g. caffeine, morphine, quinine, and strychnine, each of which occurs naturally in certain plants.
allelopathy The secretion by a plant of biochemicals which influence the growth and reproduction of nearby plants.
allopatric Having geographically separate, non-overlapping ranges of distribution. Contrast sympatric.
alternate 1. (adj.) (of leaves or flowers) Borne singly at different levels along a stem, including spiralled parts. Contrast opposite. 2. (prep.) Occurring between something else, e.g. stamens alternating with petals.
alternipetalous A configuration where parts of the flower, e.g. stamens, alternate in position with the petals.
ament A synonym of catkin.
amphitropous (of an ovule) Bent so that both ends are near each other. Contrast anatropous, campylotropous, and orthotropous.
amplexicaul With the base dilated and clasping the stem, usually of leaves.
amylum star a vegetative propagative body filled with starch (amylum) and located around the lower nodes of certain stoneworts.
anastomose Branching and then rejoining, as with leaf venation.
anastomosis A connection or fusion of two or more veins that are normally diverging or branching, thereby forming a network.
anatropous (of an ovule) Inverted so that the micropyle faces the placenta (this is the most common ovule orientation in flowering plants). Contrast amphitropous, campylotropous, and orthotropous.
ancipital Flat, with two edges (versus round).
androdioecious Having bisexual flowers and male flowers on separate individuals. Contrast andromonoecious, polygamodioecious, polygamomonoecious, and polygamous.
androecium A collective name for the male reproductive parts of a flower; the stamens of a flower considered collectively. Contrast gynoecium. Abbreviated A; e.g. A 3+3 indicates six stamens in two whorls.
androgynophore A stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth.
androgynous Having male and female flowers in the same inflorescence.
androphore The stalk or column supporting the stamens in certain flowers.
andromonoecious Having bisexual flowers and male flowers on the same individual plant. Contrast androdioecious, gynomonoecious, polygamodioecious, polygamomonoecious, and polygamous.
anemophilous Adapted to pollination by wind.
anemophily Adaptation to pollination by wind.
angiosperm A flowering plant; a plant with developing seeds enclosed in an ovary.
anisomery The condition of having a floral whorl with a different (usually smaller) number of parts from the other floral whorls.
anisotomic Branching, with branches having unequal diameters, such as a trunk and its branch. Contrast isotomic.
annual A plant that completes its life cycle (i.e. germinates, reproduces, and dies) within a single year or growing season.
annulus 1. A ring-like structure; in the form of a ring. Pappus bristles are sometimes attached to a ring called an annulus or disk at the top of the achene beak. In some pollen grains, the exine around the apertures is either thicker or thinner. In pores, this border is termed an annulus. Certain flowers have ring-like constrictions at the mouth of the flower, e.g. in Huernia and Aristolochia. 2. A ring of specialized cells on the sporangium.
anterior Positioned in front of, toward the apex. Compare distal.
anthemoid In the Compositae, a style with a brush-like tuft of sweeping hairs at the tip of each style branch.
anther The pollen-bearing part of a stamen.
antheridium in bryophytes, a specialized gametophytic organ that produces the male gametes.
antheridiophore In liverworts of the order Marchantiales, a male gametophore, a specialized, stalked structure that bears the antheridia.
antherode A sterile anther of a staminode.
anthesis 1. (of a flower) The period during which pollen is presented and/or the stigma is receptive. 2. (of a flowering plant) The period during which flowers in anthesis are present. Not defined for some cases, such as when pollen is released in the bud.
anthocarp A type of fruit in which some part of the flower persists attached to the pericarp, e.g. in Nyctaginaceae.
anthophore A stalk-like structure, internode located between the calyx and the other parts of the flower.
anticlinal Pointing up, away from, or perpendicular to a surface. Contrast periclinal.
antrorse Directed forward or upward, e.g. of hairs on a stem. Contrast retrorse.
apetalous Lacking petals.
apex pl. apices; adj. apical The tip of a structure, e.g. a leaf, shoot, stem or trunk of a tree. aphananthous (of flowers) Inconspicuous or unshowy, as opposed to phaneranthous or showy.
aphlebia pl. aphlebiae Imperfect or irregular leaf endings commonly found on ferns and fossils of ferns from the Carboniferous Period. aphyllous Leafless; having no leaves.
apical Adjectival form of apex.
apiculate especially of leaves, ending in a short triangular point. See also Leaf shape.
apiphily A form of pollination whereby pollen is distributed by honey bees.
apo- A prefix meaning "away from, separate, without".
apocarpous (of a gynoecium) Consisting of one or more carpels which are free from one another (or almost so), e.g. in members of the Ranunculaceae and Dilleniaceae.
apomixis adj. apomictic A type of asexual reproduction whereby viable seeds or spores are produced asexually, without fertilization, such that the genetic material they contain is a clone of the parent's genetic material. A plant produced in this way is called an apomict. apomorphy In cladistics, a "different form" from the form of an ancestor (i.e., an innovation) of use in determining membership in a clade.
apopetalous Having separate petals, not fused (sympetalous).
apophyllous Perianth or other segments free, not united. Compare symphyllous, gamophyllous, and polyphyllous.
apophysis 1. The external part of a cone scale. 2. An outgrowth of an organ or an enlargement of a stem.
appendage A secondary part attached to a main structure; an external growth that seldom has any obvious function, hence appendiculate.
appendiculate Having the nature of or bearing appendages.
appressed Pressed closely but not fused, e.g. leaves against a stem.
aquatic plant A plant whose natural habitat is water, living in or on water for all or a substantial part of its lifespan; generally restricted to fresh or inland waters.
arachnoid Cobwebby, from being covered with fine white hairs.
arborescent Tree-like in growth or general appearance.
arboretum pl. arboreta A taxonomically arranged collection of trees. archaeophyte A non-native plant that has nonetheless been present in a particular geographic area for some time. Contrast neophyte.
archegonium Plural archegonia. A multicellular haploid structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete. The corresponding male organ is called the antheridium.
archegoniophore In liverworts of the order Marchantiales, a female gametophore: a specialized, stalked structure that bears the archegonia and the sporophytes.
arctotoid In the Compositae, a style with a ring of sweeping hairs borne on the shaft of the style proximal to the style branches.
areolate Having or being composed of areoles, as an areolate crustose lichen.
areole 1. A space between the threads of a net, e.g. that part of a leaf surface defined by each of the elements of a vein network; as with cacti, the area between the veinlets of a leaf. 2. A structure on the stem node of a cactus, morphologically a specialised branch; the region of a cactus upon which spines, glochids, and flowers are borne.
aril A membranous or fleshy appendage formed by expansion of the funicle which partly or wholly covers a seed, e.g. the fleshy outer layer of lychee fruit, or that found in members of the Sapindaceae.
aristate With a stiff, bristle-like awn or tip. See also Leaf shape.
article A segment of a jointed stem or of a fruit with constrictions between the seeds; an organ part that separates easily from the rest of the organ at a joint or articulation.
articulate Jointed; separating freely, leaving a clean scar; e.g. the fronds of certain ferns where they join the rhizome.
ascending 1. (of a stem) Spreading horizontally, then directed upward; an ascending stem is more or less prostrate near its base, then erect. 2. (of an ovule) Attached somewhat above the base.
ascidiate Shaped like a pitcher, as with the leaves of pitcher plants, e.g. species of Nepenthes and Sarracenia.
asexual reproduction Reproduction that does not involve gametes. Often used interchangeably with vegetative reproduction.
asperulous Having a rough, sandpapery texture; e.g. some leaf surfaces.
asymmetrical Irregular or unequal; lacking any plane of symmetry; e.g. flowers of Canna.
attenuate Narrowing gradually. See also Leaf shape.
auricle An ear-shaped lobe, particularly a small, roundish, lateral appendage of a leaf or leaf-like organ.
auriculate Attached at the base with ear-shaped appendages (auricles). See also Leaf shape.
autogamous Self-pollinating, self-fertilizing – in flowering plants
awn 1. Any long, bristle-like appendage. 2. In the Poaceae, an appendage terminating or on the back of glumes or lemmas of some grass spikelets. 3. In the Geraniaceae, the part of the style that remains attached to the carpel that separates from the carpophore (column). 4. A generally straight, stiff pappus element, varying from stiffly bristle-like to hard and needle-like. In Strophanthus, the awn is the beak of the seed, stipe of the coma hairs.
axil The upper angle between one part of a plant and another, e.g. the stem and a leaf.
axile On an axis; of a placenta, on the central axis of the ovary.
axillary Borne in or arising from the axil, usually referring to the axil of a leaf.
axis The main stem of a whole plant or inflorescence; also, the line along which this stem extends.
B
baccate Fruit appearing like a berry that may or may not be a true berry.
baculiform Rod-like; longer than wide. Compare cylindrical.
barb A rear-facing point, as in a fish hook.
barbed Having barbs pointing in one direction.
barbellate Having barbed hairs (barbellae).
bark The protective external layer of tissue on the stems and roots of woody trees and shrubs; includes all of the living and non-living tissue external to the cambium.
basal Situated or attached at or close to the base (of a plant or a phylogenetic tree diagram).
basifixed Something attached by its base, e.g. an anther attached to the filament. Compare dorsifixed.
basipetal Developing sequentially from the apex toward the base (i.e. with the youngest toward the base), e.g. of flowers in an inflorescence. Also, moving from leaves to roots, e.g. of molecular signals in plants.
bathyphyll A specialized leaf produced at the base of a plant, usually when the plant is immature, and which serves to anchor the plant to a substrate; especially notable in the fern Teratophyllum. Contrast acrophyll.
beak A prominent, pointed terminal projection, especially of a carpel or fruit.
berry A type of indehiscent fruit with the seeds immersed in the pulp, e.g. a tomato.
bi- A prefix meaning "two", e.g. bisulcate, having two sulci or grooves.
biennial A plant which completes its life cycle (i.e. germinates, reproduces, and dies) within two years or growing seasons. Biennial plants usually form a basal rosette of leaves in the first year and then flower and fruit in the second year.
bifid Forked; cut in two for about half its length. Compare trifid.
bifoliate (of a compound leaf) Having precisely two leaflets, usually in a symmetrical pair, e.g. a leaf of Colophospermum mopane. Compare jugate lobed leaf, e.g. most species of Bauhinia.
bifusiform Fusiform with a pinch in the middle.
bilabiate Having two lips, e.g. the form of the petals in many irregular flowers.
bilateral 1. Having two distinguishable sides, such as the two faces of a dorsiventral leaf. 2. Arranged on opposite sides, e.g. leaves on a stem; Compare distichous and opposite. 3. Bilaterally symmetrical, as in a leaf with a symmetrical outline.
biloculate Having two loculi, e.g. in anthers or ovaries.
binomial Making use of names consisting of two words to form the scientific name (or combination) in a Latin form. For example, where the first is the name of the genus to which the species belongs, and the second is the specific epithet given to that species to distinguish it from others in the same genus.
binomial nomenclature The system of nomenclature in which the scientific name of a species (and not of a taxon at any other rank) is a combination of two names, the first name being the generic name. The second name is referred to botanically as the specific epithet. Note that the two names together (not just the second name) constitute the species name.
bipinnate Doubly pinnate; e.g. a compound leaf with individual leaflets pinnately divided.
bipinnatisect A pinnatisect leaf with deeply dissected segments.
bisexual Bearing both male and female reproductive organs; usually, flowers with both stamens and carpels; synonymous with hermaphrodite, synoecious, and monoclinous. Bisexual flowers occur only on monoecious plants. See also androgynous, monoicous, and plant reproductive morphology.
bitegmic (of an ovule) Covered by two integuments. Contrast unitegmic.
biternate Ternate, with each division divided into three.
bivalve Having two valves or hinged parts. Contrast trivalve.
blade The lamina or flattened part of a leaf, excluding the stalk or petiole.
bloom A fine white or bluish waxy powder occurring on plant parts, usually stems, leaves, and fruits. It is easily removed by rubbing.
bole The trunk of a tree, usually the portion below the lowest branch. Compare canopy.
bostrychoid Arranged on a conical surface (like a snail shell); used to describe inflorescences in which the buds are arranged in an almost helical manner on the outside of a long, tapering, conical rachis.
bract A modified leaf associated with a flower or inflorescence and differing in shape, size, or color from other leaves (and without an axillary bud).
bracteate Possessing bracts.
bracteole A small bract borne singly or in pairs on the pedicel or calyx; synonymous with bractlet.
bracteolate Possessing bracteoles (bractlets).
bracteose Having many or showy bracts.
bractlet See bracteole.
branchlet A small branch.
brevideciduous A plant that loses all of its leaves only briefly before growing new ones, so that it is leafless for only a short time, e.g. approximately two weeks.
bristle A straight, stiff hair (smooth or with minute teeth); the upper part of an awn (when the latter is bent and has a lower, stouter, and usually twisted part, called the column).
brochidodromous Pinnate leaf venation in which the secondary veins do not terminate at the leaf margin, but are joined in a succession of prominent arcs.
brochus pl. brochi Width of one lumen of a pollen grain reticulum and half of the width of the surrounding muri (walls), hence heterobrochate and homobrochate, where the lumina are of different or similar sizes, respectively. bryophyte Informally, any plant that is a moss, hornwort, or liverwort. Formally, these plants are placed in three separate divisions: hornworts (Anthocerophyta), liverworts (Marchantiophyta), and mosses (Bryophyta).
bulb A thick storage organ, usually underground, consisting of a stem and leaf bases (the inner ones fleshy).
bulbel A bulb arising from another bulb. See bulblet.
bulbil A small, deciduous bulb or tuber formed in the axil of a leaf or pinna; a means of vegetative propagation.
bulblet A bulb arising from another bulb; a bulbel.
bullate 1. Having a rounded or blister-like appearance; arched or vaulted. 2. (of a leaf) Having arched leaf tissue between each lateral vein, i.e. the veins appear depressed in the leaf surface.
burl A deformation or knot in the branches or trunk of a tree, sometimes sought after in woodworking.
burr 1. A prickly fruit. 2. A rough or prickly propagule consisting of a seed or fruit and associated floral parts or bracts.
buttress root A root growing from an above-ground stem or trunk, and providing support, e.g. commonly of Ficus macrophylla.
C
caducous Falling off early, e.g. the sepals of poppies, which fall off when the petals begin to open. Compare persistent and fugacious.
caespitose Tufted or turf-like, e.g. the growth form of some grasses and sedges.
calcarate possessing a spur.
calcareous A soil type or a lichen substrate rock type that is rich in or largely composed of calcium carbonate.
calceolate Shaped like a slipper.
calcicole A plant which thrives in calcareous soil. Also calciphile, calciphyte. Antonym: calcifuge.
callose Hardened; thickened; callous.
callus pl. calluses 1. A protruding mass of tissue 2. Undifferentiated tissue growth formed in response to wounding; may be grown in vitro. 3. In orchids, fleshy outgrowths from the labellum which can be variously shaped from papillae to plates. 4. In grasses, a hardened extension from the base of a floret (formed from the rachilla joint and/or the base of the lemma), which may or may not elongate and is often covered in hairs or bristles.
calyciflorous Having petals and stamens attached to the calyx.
calycophyll Leaf-like structure formed from a sepal or calyx lobe which enlarges, usually many-fold, before or after anthesis, especially when most of the other sepals or calyx lobes retain their original size. More extreme than an accrescent calyx, calycophylls are found in Rubiaceae. Compare semaphyll and pterophyll.
calyculate Having an epicalyx.
calyculus 1. A cup-shaped structure formed from bracts resembling an outer calyx. 2. In some Asteraceae, a circle of bracts below the involucre.
calyptra A hood or lid. See operculum.
calyx pl. calyces Collective term for the sepals of one flower; the outer whorl of a flower, usually green. Compare corolla. calyx tube A tube formed by the fusion of the sepals (calyx), at least at the base.
cambium Tissue layer that provides partially undifferentiated cells for plant growth.
campanulate Bell-shaped.
camptodromous Pinnate venation in which the secondary veins curve toward the margins, in some cases becoming nearly parallel with them, and not reconnecting with other veins to form loops.
campylotropous When the ovule is oriented transversely (i.e. with its axis at right angles to its stalk) and with a curved embryo sac. Compare amphitropus, anatropous, and orthotropous.
canaliculate Channelled; having a longitudinal groove.
canescent Approaching white in color, as in a leaf covered with white down or wool.
canopy Branches and foliage of a tree; the crown. Also refers to the protective upper layer of a forest. Compare trunk.
capillary 1. Tube, pore, or passage with a narrow, internal cross-section. 2. Slender; hair-like.
capitate 1. (of an inflorescence) Having a knob-like head, with the flowers unstalked and aggregated into a dense cluster. 2. (of a stigma) Like the head of a pin.
capitulum Dense cluster of sessile or subsessile flowers or florets, e.g. a flower head in the daisy family Asteraceae. See pseudanthium.
capsule Dry fruit formed from two or more united carpels and dehiscing when ripe (usually by splitting into pieces or opening at summit by teeth or pores).
carduoid In Asteraceae, having a style with a ring of sweeping hairs borne on the shaft of the style below the style branches.
carina See keel.
carinal canal Longitudinal cavity in the stems of Equisetum and extinct Equisetopsida, coinciding with a ridge in the stem surface.
carneous Flesh-colored, especially as applied to some flowers.
carnose, carnous Fleshy or pulpy in texture, especially as applied to some tissues or organs. Contrast coriaceous and corneous.
Caropodium Genus of flowering plants in the family Apiaceae. Native range: Turkey to Iran. Not to be confused with Carpopodium
carpel The basic female reproductive organ in angiosperms, either consisting of a single sporophyll or a single locule of a compound ovary, with a style and a stigma. The gynoecium is the collective term for all of the carpels of a single flower.
carpellary Referring to carpels or to associated structures or outgrowths of carpels, for example staminodes attached to carpels in Nymphaeaceae, were frequently referred to as carpellary attachments. The current and past usage of the terms "carpellary attachments", paracarpels, and staminodes is confused and varies among authors.
carpopodium On achenes (Cypselae), an elongation of the base of the gynoecium which looks distinct; the abscission zone, where the achene is separated from the receptacle. 2. Genus Carpopodium in the family Brassicaceae; not to be confused with Caropodium.
cartilaginous Hard and tough; gristly. Compare corneous and coriaceous.
caruncle A small piece of flesh-like tissue, typically lumpy or warty, growing on the testa near the hilum. Contrast aril.
caryopsis A dry, indehiscent, one-seeded fruit in which the seed coat is closely fused to the fruit wall, e.g. in most grasses.
Casparian strip A continuous band of suberin in the radial primary cell walls of the endodermis in vascular plant stems and roots that forms a permeability barrier to the passive diffusion of external water and solutes into the vascular tissue.
cassideous Hood-, helmet- or bonnet-shaped; generally referring to floral anatomy, e.g. in the flowers of Aconitum, Satyrium, etc.
castaneous Chestnut-colored, reddish-brown.
casual alien An exotic plant that appears with no apparent human assistance but does not develop a sustained population(s), or one that persists only by repeated new introductions. Compare alien.
cataphyll Any plant structure which is morphologically a leaf but which has at most an incidental or transient photosynthetic function. They are either shed when their main function has been completed, or are incorporated into structures where, when dead, they serve a protective or supportive purpose.
catenulate In the shape of a chain; formed of parts or cells connected as if chained together, e.g. some diatoms, algae, and cyanobacteria such as Anabaena. See also concatenate.
catkin A spike, usually pendulous, in which the mostly small flowers are unisexual and without a conspicuous perianth, e.g. in willows, poplars, oaks, and casuarinas. The individual flowers often have scaly bracts and are generally wind-pollinated. Catkins are usually shed as a unit.
caudate Having a narrow, tail-like appendage or tip, e.g. a drip tip. Contrast acuminate, cuspidate, and mucronate.
caudex pl. caudices The stem of a plant, especially a woody one; also used to mean a rootstock, or particularly a basal stem structure or storage organ from which new growth arises. Compare lignotuber. caudiciform Stem-like or caudex-like; sometimes used to mean "pachycaul", meaning "thick-stemmed".
caudicle diminutive of caudex. Meaning is context-dependent, usually referring to stem-like support of tiny items such as the pollinium of an orchid. Often used interchangeably with stipe
caulescent possessing a well-developed stem above ground, similar to cauline. Antonym: acaulescent (lacking an apparent stem).
cauliflory adj. cauliflorous Having flowers or fruits growing directly from a tree's trunk. cauline Borne on an aerial stem or caulis, as with leaves, flowers, or fruits (when applied to the latter two organs, usually referring to older stems.
caulirosulate Borne at the end of the stem or caulis, as with leaves or bracts.
cell 1. The basic, microscopic unit of plant structure, generally consisting of compartments in a viscous fluid surrounded by a cell wall. 2. A cavity of an anther or ovary.
cenanthous (of a perianth) Lacking both stamens and pistil, i.e. a flower with neither androecium nor gynoecium.
centrifixed Of a two-branched organ attached by its center, e.g. a hair or anther.
ceraceous Having a waxy appearance, color, or texture, e.g. flowers of many species of Ceropegia, and the waxy fruit of some species of Myrica.
cernuous Nodding, falling headlong or face down; inclined, stooping, or bowing forward. Applied to many species with a nodding, stooping habit, such as many Narcissus and Dierama species. Many plant species bear the specific epithet "cernua".
cespitose An alternative spelling of caespitose, meaning tufted or turf-like, e.g. the growth form of some grasses.
chamber A cavity of an ovary.
channelled Sunken below the surface, resulting in a rounded channel.
chartaceous Having a papery texture.
chasmogamous Of flowers that are pollinated when the perianth is open. Compare cleistogamous.
chasmophyte A plant adapted to growing in crevices or hollows, such as in cliff faces. Compare cremnophyte.
chimera An individual composed of two or more genetically distinct tissues, most commonly as a result of a graft and sometimes by mutations that occur during cell division or cellular transfers during seed development.
chiropterophilous Pollinated by bats.
chlorophyll Any of a variety of different chemical pigments in chloroplasts that are essential for photosynthesis.
chloroplast An organelle present in plant cells which contains chlorophyll.
chlorosis An abnormal lack or paleness of color in a normally green organ.
cilia sing. cilium; adj. ciliate Very small hairs or hair-like protrusions more or less confined to the margins of an organ, as with eyelashes; in motile cells, minute, hair-like protrusions which aid motility. cinereous Ash-colored, grayish, usually because of a covering of short hairs; somewhat darker than canescent.
circinate Spirally coiled with the tip innermost, e.g. circinate vernation of the developing fronds of most ferns.
cirrhose (of a leaf) Ending in a tendril at the apex.
cirrus See tendril.
cladode A photosynthetic branch or stem, often leaf-like and usually with foliage leaves either absent or much reduced. Compare phyllode.
cladoptosis The shedding of entire branches or shoots, rather than just individual leaves.
class The principal category for taxa ranking between division and order.
clathrate Shaped like a net or lattice; pierced with apertures, as with a cage.
clavate Club-shaped.
clavuncula In the Apocynaceae, an enlarged, drum-shaped stigma of which the sides and lower surface are the receptive zones. Coherent with the anthers or not.
claw 1. A narrow, stalk-like, basal portion of a petal, sepal, or bract. 2. In Melaleuca, the united portion of a stamen bundle.
cleistogamous Having flowers which self-pollinate and never open fully, or which self-pollinate before opening. Compare chasmogamous.
climacteric A rough category of fruit that can undergo a ripening phase post-harvest, preceded or accompanied by an increase in ethylene respiration .
climber A plant growing more or less erect by leaning on or twining around another structure for support, or by clinging with tendrils.
climbing See climber.
cline adj. clinal A continuous morphological variation in form within a species or sometimes between two species. clone A plant derived from the asexual vegetative reproduction of a parent plant, with both plants having identical genetic compositions.
coalescent Having plant parts fused or grown together to form a single unit.
cochleariform Concave and spoon-shaped.
cochleate Coiled like a snail's shell.
coenobium An arranged colony of algae that acts like a single organism.
coenocyte A single cell with multiple nuclei, formed when nuclear division was not followed by cytokinesis.
coleoptile One type of sheath in the structure of monocotyledonous seeds. The coleoptile is a protective sheath or cap (pileus), generally more or less pointed, that covers the monocotyledonous plumule as it emerges from the soil. It generally turns green and contributes to photosynthesis until its function is superseded by the main growth of the seedling. Contrast this with the coleorhiza, which remains underground until it is superseded as the roots emerge.
coleorhiza One type of sheath in the structure of monocotyledonous seeds. The coleorhiza connects the coleoptile to the radicle and protects the monocotyledonous radicle during germination. Unlike the coleoptile, the coleorhiza is associated with the root and does not emerge from the soil during germination. Contrast coleoptile.
collenchyma A specialized tissue consisting of living cells with unevenly thickened cellulose and pectin cell walls that performs a support function in organs such as leaves and young stems that are composed of primary plant tissues.
colleter A multicellular, glandular hair that usually produces a mucilaginous substance and is located on sepals, stipules, or petioles, or on nearby parts of stems; commonly found on plants in the order Gentianales.
columella In flowering plants, the tip of the central axis of the cone or fruit, e.g. in Callitris.
column 1. A structure extending above the ovary and incorporating the style and stamens also known as the gynostegium, e.g. in orchids and milkweeds. 2. In grasses, the lower, stouter, and usually twisted part of an awn, distinct from the slender upper part or bristle.
columnar Shaped like a column.
coma 1. A tuft of hairs from testa or funiculus at one or both ends of some seeds, e.g. in Strophanthus, Asclepias, or Alstonia. 2. Sterile bracts, e.g. in Curcuma, Ananas, or Eucomis. 3. Sterile flowers, e.g. in Muscari and Leopoldia, at the apex of some inflorescences. 4. A tuft of hairs at the base of some flowers, e.g. in Pfaffia gnaphalioides. 5. A tuft of hairs at the apex or base of some spikelets. 6. An axil tuft of hairs in inflorescences in some Poaceae, e.g. in Eragrostis comata.
commercial name A name often of no botanical standing and not governed by the ICNCP. The term generally applies to names such as Trademark Names, names covered by Plant Breeders Rights, Patents and Promotional Names, which are often used to enhance the sale of a plant.
commissure The seam or face at which two carpels adhere. See also fissure and suture.
community An ecological assemblage of plants that characteristically occur together.
compound Composed of several parts, e.g. a leaf composed of multiple leaflets, a gynoecium composed of multiple carpels, or an inflorescence made up of multiple smaller inflorescences.
compound palmate Having leaflets that radiate from a central point (usually at the top of a petiole), like spread-out fingers radiating from the palm of a hand. Compare palmate.
compressed Flattened lengthwise, either laterally (from side to side) or dorsally (from front to back).
concatenate Joined together in a chain-like form. See also concatenate and catenate.
concolorous Having the same color throughout; uniformly colored.
conduplicate Arranged such that two sides of a flat surface are folded along the midline to face each other. See also ptyxis, aestivation, and vernation.
cone The sexual organs, often woody, and cone-shaped or ovoid to globular, including scales, bracts, or bracteoles arranged around a central axis, found in gymnosperms, especially conifers; also sometimes used colloquially, though botanically incorrectly, for the woody fruit of some angiosperms such as Alnus and Casuarina.
conflorescence An inflorescence whose overall structure substantially differs from that of the individual branches of the inflorescence, e.g. members of the genera Callistemon, Grevillea and Hollandaea.
conical In the shape of tree crowns, with a narrow cone shape, tapering evenly from the base to the top, and circular in cross-section. Found in many conifers such as fir and spruce, an adaptation to avoid damage by winter snow. In popular texts often erroneously called "pyramidal", which differs in being broader and having a quadrate cross-section.
connate Fused to another organ (or organs) of the same kind, e.g. petals in a gamopetalous corolla tube. Compare adnate.
connective The part of an anther that connects the anther cells.
connivent Coming into contact or converging.
conspecific Belonging to the same species.
contiguous Adjoining, touching, but not united.
contort (of sepals or petals) A type of imbricate aestivation in which one side of each segment overlaps one of the adjacent segments and the other side is overlapped by the other adjacent segment. See convolute.
contorted Twisted out of the normal shape.
convolute 1. Referring to the arrangement of floral or foliar organs in a bud when each organ or segment has one edge overlapping the a