Botany

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The study of plants is called botany.

Glossary of botanical terms

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 and List of Latin and Greek words commonly used in systematic names.

Glossary of botanical terms 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 and List of Latin and Greek words commonly used in systematic names. A   In the bud Tetradenia riparia leaves had their upper surfaces turned towards the stem and the axil. The upper surface accordingly is called the adaxial surface. The lower surface faced away from the axil and is called the abaxial ("away from the axis") surface.   Viburnum abscission

  • ab- A prefix meaning "from, away from, or outside".
  • abaxial The 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 The shedding of an organ that is mature or aged, as of a ripe fruit or an old leaf.abscission zoneA specialised 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.   Welwitschia mirabilis presents an example of an acaulescent growth habit unusual in so large a plant species   Schematic diagrams of the accumbent arrangement of the cotyledons and radicle in a seed of Cheiranthus  
  • accrescent Increasing in size with age, such as a calyx that continues to grow after the corolla has fallen, e.g. in Physalis peruviana.accumbentLying against another part of the plant; when applied to a cotyledon, it means that one edge of the cotyledon lies along the radicle.-aceaeA suffix added to the 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.   Achenes on the surface of the stem of the infructescence of a strawberry
  • acicular Slender or needle-shaped.acropetalMoving from roots to leaves, e.g. of molecular signals in plants.acrophyllThe 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.   Geranium incanum flowers are actinomorphic, having five axes of symmetry, as opposed to the two axes of symmetry of the zygomorphic flowers of most species of the related genus Pelargonium
  • acute 1.  Sharply pointed, but not drawn out. Contrast accuminate.2.  Converging at an angle of less than 90°. Contrast obtuse.
  • ad- A prefix meaning "near or towards"; also meaning "added to".
  • adaxial The surface of an organ facing towards the organ's axis, e.g. the upper surface of a lateral organ such as a leaf or petal. Contrast abaxial.
  • 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 at their bases at least. See for example, Sims: "...the filaments are so closely pressed that they have the appearance of being monadelphous...".[[[2]]] 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.adherentSlightly 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.)
  • aerial Of the air; growing or borne above the surface of the ground or water.
  • 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.
  • alate Having a wing or wings.   Diagram of a coconut fruit. The albumen (endosperm) is labelled Alb.
  • 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.   Caffeine is an alkaloid with four nitrogen atoms in its carbon skeleton
  • 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.alternate1.  (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.
  • 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.
  • 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, towards the apex. Compare distal.anthemoidIn the Compositae, a style with a brush-like tuft of sweeping hairs at the tip of each style branch.
  • 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.anthophoreA stalk-like structure, internode located between the calyx and the other parts of the flower.anticlinalPointing up, away from, or perpendicular to a surface. Contrast periclinal.antrorseDirected towards or upwards, e.g. of hairs on a stem. Contrast retrorse.
  • apex pl. apices The tip; the point furthest from the point of attachment.
  • apical At or on the apex of a structure, usually a shoot, a stem, or the trunk of a tree, e.g. an apical meristem or an apical bud.apiculateespecially of leaves, ending in a short triangular point.
  • 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.
  • appendage A secondary part attached to a main structure; an external growth that seldom has any obvious function, hence appendiculate.
  • appressed Pressed closely but not fused, e.g. leaves against a stem.
  • arachnoid Cobwebby, from being covered with fine white hairs.
  • archaeophyte A non-native plant that has nonetheless been present in a particular geographic area for some time. Contrast neophyte.
  • archegonium A multicellular 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.arctotoidIn the Compositae, a style with a ring of sweeping hairs borne on the shaft of the style proximal to the style branches.
  • 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; the region of a cactus upon which spines and flowers are borne.3.  In lichenology, a polygonal piece of a thallus surface where a crustose lichen is broken up like old dried and cracked paint, or like the polygonal "islands" of dried mud in a dry lake bed.   Blighia, Akee seeds, one whole, one in longitudinal section, showing the pale aril
  • aristate With a stiff, bristle-like awn or tip.articleA 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.ascending1.  (of a stem) Spreading horizontally, then directed upwards; an ascending stem is more or less prostrate near its base, then erect.2.  (of an ovule) Attached somewhat above the base.   Infructescence of wild rye, showing prominent awns   Anatomy of an awn and bristles on a species of Australian grass
  • 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.axillaryBorne 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   Baculiform Desmid in genus Closterium.   Barbs occur on the spines of some species of cactus, as shown here enlarged baculiformRod-like; longer than wide. Compare cylindrical.barbA rear-facing point, as in a fish hook.barbedHaving barbs pointing in one direction.barbellateHaving 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.basalSituated or attached at the base.
  • basipetal Developing sequentially from the apex towards the base (i.e. with the youngest towards the base), e.g. of flowers in an inflorescence. Also, moving from leaves to roots, e.g. of molecular signals in plants.   Berries of Olinia ventosa, including cross-section of a berry, showing hard seeds in the pulp   The bifoliate compound leaves of the Mopane tree, Colophospermum mopane, suggested the common name "butterfly tree" bathyphyllA 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.beakA prominent, pointed terminal projection, especially of a carpel or fruit.
  • bi- A prefix meaning "two"; e.g. bisulcate, having two sulci or grooves.
  • 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.
  • bloom A fine white or bluish waxy powder occurring on plant parts, usually stems, leaves, and fruits. It is easily removed by rubbing.   This African Baobab tree, Adansonia digitata, has an enormous bole beneath a relatively modest canopy that is typical of this species   The large, colourful bracts of Bougainvillea are commonly mistaken for its petals   Burrs, fruits of Arctium species
  • bole The trunk of a tree, usually the portion below the lowest branch. Compare canopy.bostrychoidArranged 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.
  • branchlet A small branch.brevideciduousA 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.
  • bulb A thick storage organ, usually underground, consisting of a stem and leaf bases (the inner ones fleshy).
  • bullate Having rounded or globular blisters on the surface.
  • caespitose Tufted or turf-like, e.g. the growth form of some grasses.
  • callose Hardened; thickened; callous.callus pl. calli 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.calyciflorousHaving petals and stamens attached to the calyx.
  • calyx pl. calyces A 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 A tissue layer that provides partially undifferentiated cells for plant growth.campanulateBell-shaped.
  • canescent Approaching white in color, as in a leaf covered with white down or wool.
  • canopy The branches and foliage of a tree; the crown. Also refers to the protective upper layer of a forest. Compare trunk.
  • capillary 1.  A 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.
  • capsule A dry fruit formed from two of more united carpels and dehiscing when ripe (usually by splitting into pieces or opening at summit by teeth or pores).carduoidIn the Asteraceae, having a style with a ring of sweeping hairs borne on the shaft of the style below the style branches.carinaSee keel.carinal canalA longitudinal cavity in the stems of Equisetum and extinct Equisetopsida, coinciding with a ridge in the stem surface.carneousFlesh-coloured, especially as applied to some flowers.carnose, carnousFleshy or pulpy in texture, especially as applied to some tissues or organs. Contrast coriaceous and corneous.
  • caruncle A small piece of flesh-like tissue, typically lumpy or warty, growing on the testa near the hilum. Contrast aril.
  • 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.cassideousHood-, helmet- or bonnet-shaped; generally referring to floral anatomy, e.g. in the flowers of Aconitum, Satyrium, etc.
  • 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.
  • 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.
  • 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; synonymous with cauliflorous).
  • 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.centrifixedOf a two-branched organ attached by its centre, e.g. a hair or anther.ceraceousHaving a waxy appearance, colour, or texture, e.g. flowers of many species of Ceropegia, and the waxy fruit of some species of Myrica.cernuousNodding, falling headlong or face down; inclined, stooping, or bowing forwards. Applied to many species with a nodding, stooping habit, such as many Narcissus and Dierama species. Many plant species bear the specific epithet "cernua".
  • chartaceous Having a papery texture.chamberA cavity of an ovary.channelledSunken below the surface, resulting in a rounded channel.
  • 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.
  • 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.circinateSpirally coiled with the tip innermost, e.g. circinate vernation of the developing fronds of most ferns.
  • class The principal category for taxa ranking between division and order.clathrateShaped like a net or lattice; pierced with apertures, as with a cage.
  • cleistogamous Having flowers which self-pollinate and never open fully, or which self-pollinate before opening. Compare chasmogamous.
  • climber A plant growing more or less erect by leaning on or twining around another structure for support, or by clinging with tendrils.
  • 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.
  • 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.coleoptileOne 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.coleorhizaOne 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.
  • 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.
  • 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.
  • community An ecological assemblage of plants that characteristically occur together.compoundComposed 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 palmateHaving 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).concatenateJoined together in a chain-like form. See also wikt:concatenate and catenate.
  • concolorous Having the same colour throughout; uniformly coloured.
  • 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.contortedTwisted 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 adjacent organ or segment; a form of imbricate arrangement. See contort.2.  (of leaves) A type of vernation in which one leaf is rolled up inside another.3.  A type of vernation of two leaves at a node, in which one half of each leaf is exposed and the other half is wrapped inside the other leaf.corcleA plant embryo, plumule, or plumule plus radicle.
  • cordate Heart-shaped, with the notch lowermost; of the base of a leaf, like the notched part of a heart. Contrast obcordate.coriaceousLeathery; stiff and tough, but flexible. Compare corneous.
  • corm A fleshy, swollen stem base, usually underground and functioning in the storage of food reserves, with buds naked or covered by very thin scales; a type of rootstock. Adjectives derived from "corm" include "cormose" and "cormous".corneousHorny in texture; stiff and hard, but somewhat tough. Compare coriaceous.
  • corona 1.  In flowering plants, a ring of structures that may be united in a tube, arising from the corolla or perianth of a flower and standing between the perianth lobes and the stamens. The trumpet of a daffodil is a corona.2.  In grasses, a hardened ring of tissue surmounting the lemma in some species.
  • cortex pl. cortexes or cortices In lichens, the "skin" or outer layer of thallus tissue that covers the medulla. Fruticose lichens have one cortex encircling the branches, even flattened, leaf-like forms; foliose lichens have different upper and lower cortices; crustose, placodioid, and squamulose lichens have an upper cortex but no lower cortex; and leprose lichens lack any cortex.corticolousGrowing on bark or on wood with the bark stripped off. Compare lignicolous.
  • corymb adj. corymbose An inflorescence with branches arising at different points but reaching about the same height, giving the flower cluster a flat-topped appearance.costaA rib.costapalmateHaving a definite costa (midrib), unlike the typical palmate or fan leaf, but with the leaflets arranged radially as in a palmate leaf.
  • cotyledon The primary leaf or leaves of a plant embryo which upon germination develops into the seed-leaf or the first set of leaves.
  • crateriform In the shape of a saucer or shallow cup; hemispherical or more shallow.
  • cremnophyte A plant adapted to growing on, especially hanging from, cliff faces or crevices. Compare chasmophyte.[[[3]]][[[4]]]
  • crisped Finely curled, as with the edges of leaves and petals.
  • cross To make something interbreed; the act of hybridization.
  • crustaceous Hard, thin and brittle.crustoseForming a closely applied surface layer or crust.
  • cucullate Hood-like or hooded, commonly referring to the shape of leaves or petals, e.g. Pelargonium cucullatum. Similarly derived terms include cuculliform and cuccularis.
  • cultigen A plant whose origin or selection is primarily due to intentional human activity.
  • cultivar A term derived from "cultivated variety" denoting an assemblage of cultivated plants clearly distinguished by one or more characters (morphological, physiological, cytological, chemical, or other). When reproduced (either sexually or asexually), the assemblage retains its distinguishing characters. A cultivar may arise in cultivation or be introduced from the wild. It is a variant that is of horticultural interest or value. Cultivar names are written with single quotation marks around them, e.g. 'Blue Carpet' or 'Alba'. All new names established after 1 January 1959 must be in common language (that is, not in Latin), but names established in Latin prior to this date are retained in Latin form.
  • cultivar epithet The defining part of a name that denominates a cultivar. Cultivars are designated by fancy (q.v.) epithets appended either to the scientific name or to the common name of the taxon to which they belong; they are not italicized but placed in single quotation marks, e.g. Rubus nitidoides 'Merton Early'. 'Merton Early' is the cultivar epithet.cuneateWedge-shaped, with straight sides converging at a base.
  • cupuliform Nearly hemispherical, shaped like a cupola or dome.
  • cyme adj. cymose A type of inflorescence in which the main axis and all lateral branches end in a flower (each lateral may be repeatedly branched).
  • deciduous Dehiscing and falling seasonally, as with bark, leaves, or petals. Contrast persistent.declinateCurving downwards, and then upwards at the tip. Often qualified, e.g. declinate-ascendant.decompoundDivided to more than one level, e.g. in bipinnate leaves, in which the leaflets of what would otherwise be a pinnate leaf are themselves pinnately divided.decorticate1.  (intr. v.) To shed the outer bark of a tree, usually seasonally as part of the natural growth cycle.2.  (tr. v.) To strip the peel, crust, bark, or other surface tissues from a plant or from harvested material, such as in extracting fibre from harvested Agave leaves.decumbentHaving branches growing horizontally along the ground but which are turned up at the ends.
  • decurrent Extending downwards beyond the point of insertion, e.g. when the base of a leaf or a fungal gill is prolonged downwards along the stem in a raised line or narrow wing.decussantA synonym of decussate; the usage decussant is questionable and occurs rarely, probably as an error. The formally correct usage is decussate.decussateOpposite with successive pairs borne at right angles to the last; generally applied to the arrangement of leaves.definiteOf a constant number, e.g. twice as many stamens as petals or sepals (or less), or an inflorescence ending in a flower or an aborted floral bud, typically a cymose inflorescence. Contrast indefinite.deflexedBent downwards. Contrast inflexed.
  • diaspore Any reproductive part of a plant adapted for dispersal and for establishing new plants; may be a disseminule such as a seed, or other parts such as specialised buds, branches, inflorescences, or fruits.
  • digitate With segments spreading from a common centre, like the fingers of a hand. See also palmate and palmatisect.dimorphicOccurring in two different forms (with respect to shape and/or size), e.g. of stamens, fronds, or leaves. See also monomorphic (having a single form) and polymorphic (having many forms).
  • dioecious (of vascular plants) Having male and female reproductive structures which develop only on different individuals and never on the same individual. Contrast monoecious.
  • diploid Having two complete sets of chromosomes in the nucleus of a sporophyte cell, i.e. one set from each of the parental gametes. This is often expressed symbolically as 2n, where n = the number of chromosomes in the haploid gamete.
  • disc Also spelled disk. A plate or ring of structures derived from the receptacle, and occurring between whorls of floral parts. In some groups, especially Sapindales, the nectary is in the form of a prominent disk. In daisies, the central part of the capitulum is a disk, hence flowers borne there are called disk flowers or florets.discoidResembling a disc or plate, having both thickness and parallel faces and with a rounded margin. Also used to describe the flower head of Asteraceae where there are no ray florets but only disc florets.   Disk florets opening in a capitulum of a cultivated Helianthus. They open progressively from the edge to the centre of the disk. discolorous(of leaves) Having upper and lower surfaces of different colours.
  • disjunct Occurring in widely separated geographic areas, distinctly separate; applies to a discontinuous range in which one or more populations are separated from other potentially interbreeding populations with sufficient distance so as to preclude gene flow between them.disk floretA floret occurring most typically in the disk of the capitulum of flowers in the family Asteraceae, and to some extent in other plants that bear a flowering head with a disk, such as Scabiosa.dissectedDeeply divided; cut into many segments.   Boophone disticha has conspicuously distichous leaves dissepimentA partition or septum in a plant part, usually referring to septa between the loculi of capsules or of other fruits with multiple partitions.
  • distal Remote from the point of origin or attachment; the free end. Contrast proximal.
  • distichous Arranged in two opposite rows (and hence in the same plane).distinctSeparate or free; not united.
  • distyly The condition in which the flowers of a species occur in two forms that differ only by the length of the style and stamens, and flowers of only one of these forms appear on any one plant. Compare heterostyly.   Domatia at the bases of the thorns of Acacia drepanolobium, the "Whistling Thorn". Note the access holes.
  • diurnal Of the day; occurring or opening in the daytime.
  • divaricate Wide-spreading.divergentSpreading in different directions, generally upward.
  • division A taxonomic rank below kingdom in the standard taxonomic hierarchy. "Division" is generally used only for plants, and is the approximate botanical equivalent of the term phylum, which is used for animals and other kingdoms.
  • domatia sing. domatium Any hollow structure formed by a plant that is inhabited by animals such as ants or mites.   Dorsiventral (bilateral) leaves of Syzygium gerrardii and Triadica sebifera
  • dorsal From Latin dorsum, a ridge or the back of an animal. Partly because the term originally referred to animals rather than plants, usage in botany is arbitrary according to context and source. In general "dorsal" refers to "the rear or back or upper surface", but in botanical usage such concepts are not always clearly defined and may be contradictory. For example: facing away from the axis (abaxial) in a lateral organ of an erect plant facing away from the substrate in any part of an erect plant, for example the upper surface of a more or less horizontal leaf (adaxial) or the upper part of the crown of the plant facing away from the substrate in a prostrate or climbing plant or floating leaves such as those of Nymphaea. Derived or related terms include dorsad, "towards the dorsal", and dorsum, "the dorsal part of the organ or organism as a unit". Related anatomical terms of location include ventral, lateral.dorsifixedAttached at or by the back, e.g. anthers on a filament.
  • dorsiventral Having structurally and visibly different upper and lower surfaces, e.g. some leaves. Compare bilateral and isobilateral.     Leaves of Epipremnum aureum have a cuspidate drip tip drip tipA long, narrow, acuminate, caudate, or cuspidate extension at the tip of a leaf or leaflet. Commonly an adaptation to rainy conditions, as it promotes shedding of water by its dripping from the narrow tip. The term "drip tip" is not anatomically descriptive in the way that say, acuminate or cuspidate, are; rather it is a description of the functional shape that aids dripping, irrespective of the specific geometry of the shape itself.
  • druse A globular mass of calcium oxalate crystals, usually with the crystals radiating from an organic core. E   Plants of the genus Corydalis bear seeds with attached elaiosomes, which have various functions, commonly attracting ants. On some Corydalis species, elaiosomes that attract ants also repel mice.[[[5]]]   Petals of Heracleum sphondylium are variously emarginate at their tips—flowers in the middle of the inflorescence have slightly emarginate petals, whereas flowers at the periphery are so deeply emarginate as to be almost cleft in two.   Water lilies and reeds represent two ecological categories of emergent aquatic vegetation
  • edaphic Of or influenced by the soil.
  • elaiosome An external structure attached to the seed of many species of plants. Elaiosomes generally look fleshy and in some species they are rich in oils or other nutritious materials. Their functions vary and are not always obvious; commonly they attract ants or other animals that aid in dispersal, but they may also repel other animals from eating the seed.[[[5]]]elephophilyA form of pollination whereby pollen or spores are distributed by the feet of elephants, as in Rafflesia arnoldii.
  • elliptical Also elliptic. Planar, shaped like a flattened circle, symmetrical about both the long and the short axis, tapering equally both to the tip and the base; oval.   embryo}} emerging from the upper surface of the sprouting date seed is tiny in comparison to the endosperm, its main food supply, which comprises almost all of the rest of the seed
  • embryo The young plant contained by a seed prior to germination.emergentA plant taller than the surrounding vegetation or, among aquatic plant species, one that bears flowers and commonly leaves above the surface of the water. Aquatic examples include water lilies, reeds, and papyrus. Some pondweeds such as Stuckenia are not emergent until they flower, at which time only their flowers appear above the water surface.enantiostylyThe condition in which the gynoecium protrudes laterally, to the right (dextrostyly) or to the left (sinistrostyly) of the androecium, e.g. Senna.
  • endemic Having a natural distribution restricted to a particular geographic region. Compare native.
  • endocarp The innermost layer of the wall of a fruit; in a drupe, the stony layer surrounding the seed.
  • ensiform Shaped like the blade of a sword.
  • epicarp The outer layer of the wall of a fruit, i.e. the "skin".
  • epicotyl The part of the plant axis or stem between the cotyledonary node and the first foliage leaves.
  • epidermis An organ's outermost layer of cells, usually only one cell thick.
  • epiphyte A plant, alga or fungus that grows on another plant without deriving nourishment from it but using it for support.
  • epithet The adjectival component in a binomial scientific name, usually more specifically called a specific epithet; the final word or combination of words in a name of more than one word (other than a term denoting rank) that denominates an individual taxon. The simplest and commonest example is the second word in a two-word name of a species, such as "mirabilis" in Welwitschia mirabilis.   Seeds or fruits are dispersed by epizoochory when they stick to the fur of animals epizoochoryA type of seed dispersal that occurs when seeds or fruits physically adhere to the outside of vertebrate animal bodies.epruinoseNot pruinose.   The bases of equitant leaves enclose later leaves on the stem equitant(of a leaf) Folded lengthwise and clasping another leaf.erectUpright, more or less perpendicular to the ground or point of attachment. Compare patent (spreading) and erecto-patent, between erect and patent.
  • ericoid Having leaves like those of the European heaths (Erica); small and sharply pointed.
  • exotic Not native; introduced from another region or country.
  • F1 hybrid A single cross; a plant breeding term for the result of a repeatable cross between two pure bred lines.
  • F2 hybrid A plant breeding term for the result of a plant arising from a cross between two F1 hybrids; may also refer to self-pollination in a population of F1 hybrids.
  • family A taxonomic group of one or more genera with features and/or ancestry in common; the term for the principal rank between order and genus.farinapowdery, pale yellow crystalline secretion consisting of flavonoids in Primula and other species
  • faucal Pertaining to the fauces; located in the throat of a calyx or corolla.faucesThe throat of a calyx or corolla; the conspicuously widened portion between the mouth and the apex of the tube. In Boraginaceae, the site of distinctive appendages.
  • fertile Capable of producing fruit; of flowers when they produce seed or of anthers containing pollen.
  • fiber 1.  A fiber cell.2.  Any flexible, strong, stringy, and very elongate structure.
  • fiber cell a type of cell that is found in sclerenchyma, it is much elongated and dies soon after an extensive modification of its cell wall. The cell wall is usually thickly lignified, but is sometimes gelatinous.filament1.  The stalk of a stamen.2.  Any very narrow, thread-like structure that is one or a few cells thick.filamentousconsisting of filaments or fibres, hairlike.filiformthread-like. e.g. stamen filaments, or leaf shapes.fimbriaslender hair-like process (plural: fimbriae)fimbriateFringed.
  • fissure A split or crack, often referring to fissured bark; a line or opening of dehiscence.
  • fistulose Hollow; usually applied to a tube-shaped cavity, as in a reed.
  • flabellate Fan-shaped.flaccidLimp; tending to wilt. Compare turgid.flexistylyDepending on the degree of maturation of the stamens, the style moves up or down (cataflexistyle or (ana-)hyperflexisyle).
  • flexuous (flexuose)Bent alternately in different directions; zig-zag.
  • floccose Having a soft and woolly covering of hairs.
  • flora 1.  all the plants growing in a certain region or country.2.  an enumeration of them, generally with a guide to their identification (e.g. the present volume, the Flora of Victoria, the Flora of New South Wales and so on). In this case 'flora' is written with a capital F.floral envelopeSee perianth.
  • floral leaves The upper leaves at the base of the flowering branches.
  • floral diagram A graphical means to describe flower structure, usually a schematic cross-section through a young flower.
  • follicle A dry fruit formed from one carpel, splitting along a single suture, to which the seeds are attached. Compare pod (of legume).
  • foliole A small leaf-like appendage on the front or back.   Medicago sativa, commonly known as Alfalfa or Lucerne, is an agriculturally important forb, grown in large volumes for forage, soil improvement, and other purposes.   Foveolate seeds of Physochlaina physaloides folioseLeaf-like; flattened like a leaf.
  • forest Vegetation dominated by trees with single trunks (including closely arranged trees with or without an understory of shrubs and herbs).forma (in common usage, form)A taxonomic category subordinate to species and within the taxonomic hierarchy, below variety (varietas), and usually differentiated by a minor character.foveolateHaving regular tiny pits. Compare faveolate.freeNot united with other organs of the same type; not attached at one end.
  • free central Of placentation, ovules attached to a free-standing column in the centre of a unilocular ovary.
  • fruit A seed-bearing structure present in all angiosperms, formed from the mature ovary and sometimes associated floral parts upon fertilization.fugaciousDisappearing, falling off, or withering. Compare persistent and caducous.funicle (funiculus)The stalk of an ovule.
  • funnelform Having a form gradually widening from the base to apex; funnel-shaped.
  • furcate Forked, usually applied to a terminal division; with two long lobes.fusedJoined together.
  • fusiform Rod-shaped and narrowing gradually from the middle towards each end; spindle-shaped. G   Galbulus: berry-like, fleshy cones on the coniferous tree, Podocarpus elatus   Gametophores borne on a gametophyte of a Chara species of Algae. The gametophores shown here are red male antheridia, and brown female archegonia.   Longitudinal section of immature male pine cone, showing male gametophytes (pollen grains) developing between the cone scales   Glandular hairs on the stem of Geranium dissectum
  • gall Abnormal outgrowth on external plant tissues, caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites.
  • gamete A cell or nucleus that fuses with another of the opposite sex during sexual reproduction.
  • gametophyte The haploid multicellular phase in the alternation of generations of plants and algae that bears gametes. In bryophytes the gametophyte is the dominant vegetative phase; in ferns and their allies it is a small free-living plant known as the prothallus; in gymnosperms and angiosperms the gametophytes are reduced to microscopic structures dependent on the sporophyte, male gametophytes contained in pollen grains and females contained within the ovules.
  • gemma an asexual reproductive structure found in liverworts and mosses.
  • gene pool The complete range of genetic variation found within a population.
  • genus pl. genera A group of one or more {{#species|species}} with features or ancestry (or both) in common. Genus is the principal category of taxa intermediate in rank between family and species in the standard nomenclatural hierarchy.
  • genotype The genetic make-up of an individual.
  • germination 1.  of seeds, describing the complex sequence of physiological and structural changes that occur from resting to growth stage.2.  of a pollen grain; production of a pollen tube when contacting a stigma receptive to it.3.  of a spore of fungi/bacterium; change of state – from resting to vegetative.gibbous (gibbose)(of part of an organ) Swollen, usually with a pouch-like enlargement at the base.
  • gland A secretory structure within or on the surface of a plant.     The leaves, buds, and young stalks of Eucalyptus macrocarpa are glaucous, covered with a thick waxy pruinosity
  • glaucous Describes the external surface of a plant part that has a whitish covering, in some cases with a blueish cast. Often applied to plants with a woolly or arachnoid surface, but properly referring to pruinose surfaces, meaning those with a waxy bloom. The surface of the young leaves of many eucalypts provide good examples, and so do some xerophytes.
  • globose Also globular. Roughly spherical. See also subglobose.   Glochids at the base of an Opuntia cactus spine.   Glumes of a grass species with a fairly large inflorescence globuloseApproximately spherical.
  • glochid A tiny barbed hair or bristle, e.g. the fine defensive hairs in cactus species such as Opuntia.
  • glumes bracts subtending the floret(s) of a sedge, or similar plant; in grasses forming the lowermost organs of a spikelet (there are usually 2 but 1 is sometimes reduced; or rarely, both are absent).
  • graft 1.  The artificial union of plant parts.2.  A plant shoot suitable for grafting; loosely, a scion, sucker, or branch.
  • graminoid granular(of a surface) Covered with small rounded protuberances.
  • grass A plant of the family Poaceae.   Scanning electron micrograph of a stoma on the leaf of Haemanthus. The two lip-shaped cells on either side of the gap are the guard cells
  • groundcover 1.  Dense vegetation that covers the ground.2.  A term applied to describe a plant that covers the soil surface so densely that it smothers all beneath it.
  • group A formal category equivalent to or below the rank of genus which distinguishes: an assemblage of two or more cultivars within a species or hybrid; plants derived from a hybrid in which one or more of the parent species is not known or is of uncertain origin; a range of cultivated plants of a species or hybrid which may exhibit variation but share one or more characters, which makes it worth distinguishing them as a unit.
  • guard cell Each of two cells surrounding the stoma which control gas exchange between the apoplast of the plant and the external environment.guttateHaving droplet-shaped spots. Compare punctate and maculate.guttationThe secretion of liquid water from uninjured plant parts. See hydathode.
  • guttulate Having or appearing to be spotted with oil droplets; of spores, having oil droplets inside.
  • gymnosperm A seed-bearing plant with unenclosed ovules borne on the surface of a sporophyll. Gymnosperms are among the oldest clades of vascular plants, and today are represented by approximately 1,000 extant species worldwide, including, among others, conifers, Ginkgo, Gnetum and cycads. Compare angiosperm.
  • gynodioecious Of a species, with some plants bearing only bisexual flowers and others bearing only female flowers.
  • gynoecium The collective term for the female reproductive parts of a flower or for the carpels of a flower, whether united or free. Contrast androecium. Abbreviation: G. For instance, G indicates a superior ovary; G(5) indicates having five fused carpels.
  • habit The general external appearance of a plant, including size, shape, texture and orientation.
  • habitat The place where a plant lives; the environmental conditions of its home.
  • hair A single elongated cell or row of cells borne on the surface of an organ.
  • halonate Having a transparent coating, or being of a spore's outer layer.
  • halophyte A plant adapted to living in highly saline habitats; a plant that accumulates high concentrations of salt in its tissues.   Haplostemonous arrangement of stamens and petals
  • hand-pollination The controlled act of pollination that excludes the possibility of open-pollination.
  • haploid Having one set of chromosomes, e.g. the complement of chromosomes in each of the cells of the gametophyte, the nucleus of a gamete and the spores. This is expressed symbolically as n, where n = the gametic number of chromosomes. Compare diploid, triploid, and tetraploid.
  • hapter An attachment that may form when a foliose lichen thallus comes in contact with a substrate.   The swollen haustorium of Viscum capense leaves the end of the branch stunted compared to the lower part of the branch
  • harmomegathy process by which pollen grains in arid environments close off their apertures to avoid losing water
  • hastate Triangular in outline, the basal lobes pointing outwards, so that the base appears truncate; may refer only to the base of a leaf with such lobes. Compare sagittate which refers to basal lobes pointing backwards.
  • haustorium In parasitic plants, a structure developed for penetrating the host's tissues.
  • helicoid Coiled; of a cymose inflorescence, when the branching is repeatedly on the same side (the apex is often recurved). Compare scorpioid.hemi-legumeA legume fruit in which the seed or seeds and one valve of the pod are dispersed as a unit. The valve catches the wind and blows away with the seeds, as in Acacia tenuifolia, Peltogyne paniculata.
  • herb Any vascular plant that does not develop a woody stem at any point during its life cycle, e.g. a violet.   Heteroblastic growth is common in Eucalyptus species with leaves that are isobilateral in the mature tree; they generally start life with dorsiventral leaves. Some of these saplings are in the transient stage in which they have both forms of leaves, dorsiventral below, and isobilateral above.
  • herbarium pl. herbaria A collection of preserved, usually pressed and dried, plant material used for identification and comparison; also a building in which such collections are stored.
  • heteroblastic Having parts, especially leaves, that are distinctly different between the juvenile and adult stages.
  • heteromorphic Having two or more distinct morphologies (e.g. of different size and shape).
  • heterospory The production of spores of two different sizes (small and large) by the sporophytes of land plants.     The hilum of the seeds of many species contrasts conspicuously with the rest of the #testa~testa. In the case of Erythrina species, it may be a warning that the seeds are poisonous
  • heterostyly The condition of a species having flowers with different style and stamen lengths, but with all the flowers of any one plant being identical. see:distyly
  • hilum The scar on a seed coat where it separates from its stalk (funicle).
  • hip The fruit of a rose plant.
  • hispid Bearing long, erect, rigid hairs or bristles, harsh to touch.hoaryCovered with a greyish to whitish layer of very short, closely interwoven hairs, giving a frosted appearance.
  • homochlamydeous Having a perianth which is not divided into a separate calyx and corolla. Contrast dichlamydeous.hort. (never capitalised) Of gardens, an author citation used in two ways: as a name misapplied by gardeners2.  as an invalid name derived from horticultural writings of confused authorship.     A hypocarpium forms below the fruits of Sassafras albidum
  • hyaline Translucent; usually delicately membranous and colourless.
  • hybrid A plant produced by the crossing of parents belonging to two different named groups, e.g. genera, species, varieties, subspecies, forma and so on; i.e. the progeny resulting within and between two different plants. An F1 hybrid is the primary product of such a cross. An F2 hybrid is a plant arising from a cross between two F1 hybrids (or from the self-pollination of an F1 hybrid).
  • hybrid formula The names of the parents of a hybrid joined by a multiplication sign, e.g. Cytisus ardonoi × C. purgans.
  • hydrophily A form of pollination whereby pollen is distributed by the flow of waters.
  • hypanthium A tube or cup-like structure in a flower that includes the bases of sepals, petals, and stamens, and may or may not be connected (adnate) to the ovary.   Flowers, fruit and propagule of a Rhizophora "mangle" or "mangrove". The apparent root of the propagule is in fact meristematic tissue developing from the hypocotyl. The new plant develops largely from this tissue, especially if it has successfully penetrated into mud in which the new plant can establish.
  • hyper-resupinate In botany, describing leaves or flowers that are in the usual position, but are borne on a petiole or pedicel, respectively, that is twisted 360 degrees. The term is used to describe organs, such as orchid flowers, that are usually resupinate. Compare #resupinate.hypocarpiumAn enlarged fleshy structure that forms below the fruit, from the receptacle or hypanthium.
  • hypocotyl Of an embryo or seedling, the part of the plant axis below the cotyledon and node, but above the root. It marks the transition from root to stem development.
  • idioblast A cell, especially of a leaf, differing markedly from surrounding cells. They often synthesise specialised products such as crystals.
  • illegitimate name (nomen illeg.)A name not abiding by the rules of the botanical Codes, e.g. later homonyms, cultivars that have been Latinised after 1 Jan 1959; cultivar names with more than 10 syllables or 30 letters; cultivar names that use confusing names of other plants, e.g. Camellia 'Rose'.   Melia azedarach doubly imparipinnate compound leaf
  • imbricate From the Latin for "tiled". Overlapping each other; of perianth parts, edges overlapping in the bud (the convoluted arrangement is a special form of imbrication). Dormant buds of many deciduous species are imbricately covered with protective cataphylls called bud scales.
  • incised Cut deeply and (usually) unevenly (a condition intermediate between toothed and lobed).includedEnclosed, not protruding, e.g. stamens within the corolla.   incomplete flowerA flower which lacks one or more of its usual parts, such as carpels, sepals, petals, pistils, or stamens.incurvedBent or curved inwards; of leaf margins, when curved towards the adaxial side.ined.An abbreviation of Latin inedita, an unpublished work. Used to indicate that a botanical name appeared only in a manuscript that was not published, so the name is invalid.indefinitevariable in number, and as a rule numerous, e.g. more than twice as many stamens as petals or sepals, but no particular standard number of stamens. In another usage it is a synonym for the preferable term indeterminate, meaning the condition in which an inflorescence is not terminated by a flower, but continues growing until limited by physiological factors. Compare numerous. Contrast definite.
  • indeterminate usually referring to a stem or inflorescence in which there is no particular terminal bud or meristem that stops growth and ends the extension of the stem, which continues until physiological factors stop the growth. Racemes of some Xanthorrhoeaceae, such as many Aloes, and of many Iridaceae, such as Watsonias, are indeterminate. Contrast determinate.
  • indigenous native to the area, not introduced, and not necessarily confined to the region discussed or present throughout it (hardly distinct from ‘native’ but usually applied to a smaller area). For example, the Cootamundra Wattle is native to Australia but indigenous to the Cootamundra region of southern New South Wales. Compare endemic.
  • indumentum a collective term for a surface covering of any kind of trichomes, e.g. hairs, scales.   The leaves of Syagrus palms are induplicately folded, in contrast to many other palm genera with reduplicate leaves.   Stamens of Calotropis gigantea are inserted at the base of the corolla.   The intramarginal veins near the margins of this leaf are outlined in white.   Two of these three green Asteraceae involucres encase unopened flower heads, and the third supports the open colorful head of emerging flowers. The imbricate phyllaries round the heads of this Malacothrix coulteri suggest the keeled scales of a snake, giving the plant its common name: "snake's head".   Iridescent tissues are unusual in plants, but this Begonia leaf shows some iridescence . induplicatefolded upwards, or folded with the two adaxial surfaces together.
  • indusium 1.  a membrane covering the sporangia of some ferns.2.  a cup enclosing the stigma in Goodeniaceae.inferior(of an ovary) At least partly below the level of attachment of other floral parts. Contrast superior.inflatedswollen, like a bladder.inflexedbent sharply upwards or forwards. Compare deflexed.
  • inflorescence several flowers closely grouped together to form an efficient structured unit; the grouping or arrangement of flowers on a plant.infraspecificdenotes taxonomic ranks below species level, for example subspecies.
  • infrageneric denoting taxonomic ranks below the genus level, for example, subgenera, sections, and series.
  • insectivorous catching, and drawing nutriment from, insects.insertion, point ofThe point at which one organ or structure (such as a leaf) is joined to the structure which bears it (such as a stem).insertedgrowing out from
  • integument in general, any covering, but especially the covering of an ovule.intercalary(e.g. of growth) occurring between the apex and the base of an organ
  • interjugary glands in pinnate leaves, glands occurring along the leaf rachis between the pinnae (occurring below the single, and often slightly larger, gland at or just below the insertion of the pinnae). Compare jugary.internodeThe portion of a stem between two nodes.
  • involucre A structure surrounding or supporting, usually a head of flowers. In Asteraceae, it is the group of phyllaries (bracts) surrounding the inflorescence before opening, then supporting the cup-like receptacle on which the head of flowers sits. In Euphorbiaceae it is the cuplike structure that holds the nectar glands, nectar, and head of flowers, and sits above the bract-like cyathophyll structure. Involucres occur in Marchantiophyta, Cycads, fungi, and many other groups.involuteRolled inwards, for example when the margins of a leaf are rolled towards the adaxial (usually upper) surface. Compare revolute.
  • isidium pl. isidia A warty of club-like structure in some lichens that breaks off and forms new lichens without sexual reproduction. Isidia are dispersed by mechanical means, compared to soredia, which are dispersed by wind.
  • isobifacial (of flat structures, especially leaves) Having both surfaces similar, usually referring to cell types or to the number and distribution of stomata.
  • isotomic Having branches of equal diameter. Compare anisotomic.   J jointA node or junction of two parts; articulation.   Acacia karroo bipinnate leaf A. Rachilla B. Pinnule C. Jugary glands D. Juga (plural of jugum) E. Base of petiole F. Petiolary gland G. Rachis
  • jugate yoke-like; describing a structure of paired items joined together as in a jugum or something yoke-like, such as some leaves and fruit.
  • jugum applied to various yoke-like organs, usually in the sense of their being paired, such as a pair of pinnae on a rachis.
  • juvenile leaves Leaves formed on a young plant, typically differing from the adult leaves in form. K   One form of the kettle traps of a pitcher plant.   Kidney-shaped leaf of Cucurbita maxima   typical knee at a node in a grass stem   Unusually dense stand of cypress knees around the parent tree. K, K+, K-In lichenology, "K" is the abbreviation for the outcome of a test in which a 10% solution of potassium hydroxide (KOH — hence "K") is placed on lichen tissues. Color change is noted by "K-" for none, and K+ for a yellow to red or purple color.
  • keel adj. keeled A prominent longitudinal ridge like the keel of a boat, e.g. the structure of the corolla formed by the fusion of the lower edge of the two abaxial anterior petals of flowers in the Fabaceae.kernelSee drupe.kettle trapanother term for the kettle-like pitchers of any of the carnivorous pitcher plants, in which they trap their prey.
  • kingdom the highest generally employed category of the taxonomic hierarchy, above that of division (phylum). The Plant Kingdom includes vascular plants, bryophytes and green algae and is also known as the clade Viridiplantae.KlausenfruchtKlausen or Klausenfrucht (german) is a special type of fruits in Lamiaceae and Boraginaceae. A dry, dehiscent fruit formed from a superior ovary with axil or basal placentation, with an adherent calyx, from more than one carpel and usually breaking apart into 1-seeded units by separating each carpel by false septa. One unit is a half carpel, mostly there are four units, seeds. English terms are eremocarp, schizocarp, mericarp or nutlets.
  • knee abrupt bend in a root or stem, commonly at a node; a cypress knee, or pneumatophore, is a type of bend or knob in the root of some plants, especially conifers such as some of the Taxodioideae, that shows as a projection of the root above ground level or mud level.   L   Labiate flowers of Prunella vulgaris   Laciniate, deeply incised, leaves of Pelargonium crispum.   Most Euphorbias are laticiferous and instantly exude latex when even mildly punctured, as shown here.
  • laciniate Of lobes – with ends irregularly divided into deeply divided, narrow, pointed segments; Of margins – deeply divided into pointed segments in an irregular manner.lacunaAn empty space, hole, cavity, pit, depression, or discontinuity.
  • lamella a thin, plate-like layer. (plural lamellae; adjective lamellate – composed of an assemblage of many layers)
  • laminal of, or pertaining to, the upper surface, such as the cortex of a lichen.lanatecovered in or composed of woolly hairs.
  • lanceolate longer than broad, narrowly ovate, broadest in the lower half and tapering to the tip, like a lance or spear head; (sometimes, and incorrectly, used to mean narrowly elliptic).
  • lateral attached to the side of an organ, e.g. leaves or branches on a stem. For more detail see dorsal.
  • leaf an outgrowth of a stem, usually flat and green; its main function is food manufacture by photosynthesis. Abbreviation: lvs.
  • legume 1.  a fruit characteristic of the family Fabaceae, formed from one carpel and either dehiscent along both sides, or indehiscent.2.  a crop species in the family Fabaceae.3.  a plant of the family Fabaceae.
  • lenticel   loculicidal dehiscence of a fruit capsule; the locule walls split at the back, and the valves separate, bearing the septa on their centres   The lomentum (or loment) of Hedysarum occidentale splits into single-seeded segments along the visible lines of weakness when ripe. Typically lens-shaped (lenticular) porous tissue in bark with large intercellular spaces that allows direct exchange of gases between the internal tissues and atmosphere through the bark.
  • lepidote covered with small scales.leprosepowdery
  • liana a woody climbing plant, rooted in the ground (liane is also used).lianea woody climbing plant, rooted in the ground. See also liana.
  • lichenicolous growing on or in lichens, often but not necessarily as parasitesligneoushaving hard lignified tissues or woody parts, woodylignumDead wood, typically in the context of a substrate for lichens.lignicolousGrowing on wood tissue after bark as fallen or been stripped off (compare to corticolous)
  • lignotuber a woody swelling of the stem below or just above the ground; contains adventitious buds from which new shoots can develop, e.g. after fire.
  • ligule 1.  A small membranous appendage on the top of the sheath of grass leaves.2.  A minute adaxial appendage near the base of a leaf, e.g. in Selaginella.3.  An extended, strap-like corolla in some daisy florets.linea, line, British line, Paris lineVarious pre-metric units somewhat larger than 2 mm, used in botany into the 20th century. See Line (unit) and Paris line.linearVery narrow in relation to its length, with the sides mostly parallel. See Leaf shape.
  • lobe Part of a leaf (or other organ), often rounded and formed by incisions to about halfway to the midrib.
  • lodicule One of two or three minute organs at the base of the ovary of a grass flower, representing parts of a strongly reduced perianth.
  • lomentum or lomentA pod-like indehiscent fruit that develops constrictions between the segments and at maturity breaks into one-seeded segments instead of splitting open.
  • lunate Crescent-shaped.lumenThe cavity bounded by a plant cell wall.
  • lyrate Lyre-shaped; deeply lobed, with a large terminal lobe and smaller lateral ones. M   Maculate leaves   Eucalyptus socialis, showing its mallee habit, a single tree with several trunks growing from an underground lignotuber   Mast. In particular, beechmast on the forest floor   Geranium incanum schizocarp and mericarp   Apical meristem in root tip: 1: Meristem 2: Columella     showing statocytes with statoliths 3: Lateral part of the tip 4: Dead cells 5: Elongation zone   Mesophyll as seen in the cross section of a dicotyledonous leaf A-Lower epidermis B-Lower palisade mesophyll C-Upper epidermis D-Upper palisade mesophyll E- Spongy mesophyll F-Leaf vein.   Longitudinal section of Pinus ovule A=Gametophyte B=Egg cell C=Micropyle D=Integument E=Megasporangium   Strobilus of a Selaginella A-Megaspore B-Microsporangium C-Megasporangium D-Microspore E-Sporophyll maculateSpotted; marked with spots.male flowerSee staminate flower.
  • mallee A growth habit in which several woody stems arise separately from a lignotuber; a plant with such a growth habit, e.g. many Eucalyptus species; vegetation characterized by such plants.
  • mangrove Any shrub or small tree growing in salt or brackish water, usually characterized by pneumatophores; any tropical coastal vegetation characterized by such species.
  • margin The edge of a structure, as in the edge of a leaf blade.marginalOccurring at or very close to a margin.
  • marsh A waterlogged area or swamp.
  • mast Edible fruit and nuts produced by woody species of plants (e.g. acorns and beechmast) which is consumed on the ground by wildlife species and some domestic animals.mealyCovered with coarse, floury powder.medulla1.  In a lichen, the typically undifferentiated tissue underneath the cortex of the thallus, or between the upper and lower cortex if both are present. The medulla is analogous to the tissues underneath the epidermis (skin) of a leaf. The uppermost region commonly contains most of the photobionts.2.  pith. See also medullary rays in wood.megasporangiumthe larger of two kinds of sporangium produced by heterosporous plants, producing large spores that contain the female gametophytes. Compare microsporangium.
  • membranous thin, translucent and flexible, seldom green.
  • mericarp one segment of a fruit (a schizocarp) that splits at maturity into units derived from the individual carpels, or a carpel, usually 1-seeded, released by the break-up at maturity of a fruit formed from 2 or more joined carpels.
  • meristem Any actively dividing plant tissue.
  • mesic Moist, avoiding both extremes of drought and wet; pertaining to conditions of moderate moisture or water supply; applied to organisms (vegetation) occupying moist habitats.
  • mesocarp The fleshy portion of the wall of a succulent fruit inside the skin and outside the stony layer (if any), surrounding the seed(s); sarcocarp.mesomorphicSoft and with little fibrous tissue, but not succulent.mesophyll1.  The parenchyma tissues between the upper and lower epidermis. They vary in function, but usually include the photosynthetic tissue of a leaf2.  In ecology, the blade of a leaf or leaflet that has a surface area 4500–18225 mm2; a plant, or vegetation, that has mesophyll (sized) leaves.mesophyllous(of vegetation) Of moist habitats and having mostly large and soft leaves.
  • mesophyte A plant thriving under intermediate environmental conditions of moderate moisture and temperature, without major seasonal fluctuations.
  • midrib Also midvein. The central and usually most prominent vein of a leaf or leaf-like organ.
  • midvein See midrib.   Moniliform pods on Acacia nilotica monadA single individual that is free from other individuals, not united with them into a group. The term is usually used for pollen to distinguish single grains from tetrads or polyads.
  • monoecious (of vascular plants) Hermaphroditic, with all flowers bisexual, or with male and female reproductive structures in separate flowers but on the same plant, or of an inflorescence that has unisexual flowers of both sexes. Contrast dioecious.
  • monograph Of a group of plants, a comprehensive treatise presenting an analysis and synthesis of taxonomic knowledge of that taxon; the fullest account possible (at the time) of a family, tribe or genus. It is generally worldwide in scope and evaluates all taxonomic treatments of that taxon including studies of its evolutionary relationships with other related taxa, and cytological, genetic, morphological, palaeobotanical and ecological studies. The term is often incorrectly applied to any systematic work devoted to a single taxon. Compare revision.
  • monotypic Containing only one taxon of the next lower rank, e.g. a family with only one genus, or a genus that includes only a single species.
  • morphology The shape or form of an organism or part thereof.
  • mucro Diminutive: mucronule. A sharp, short point, generally at the tip of a leaf or the tip of the midrib of a compound leaf.[[[3]]]
  • mycelium The "vegetative" (nonreproductive) part of a fungus, mostly composed of aggregations of hyphae. It functions in substrate decomposition and absorption of nutrients.
  • mycorrhiza pl. mycorrhizae; adj. mycorrhizal One of several types of symbiotic association between a fungus and the roots of a plant.
  • mycotroph adj. mycotrophic A plant that obtains most or all of its carbon, water, and nutrients by associating with a fungus. N   Hoya carnosa secretes so much nectar that it fall in drops if no pollinators remove it   Helleborus argutifolius has its small green petals modified into floral nectaries. The sepals function as petals   Nylanderia flavipes is an example of a plant with extrafloral nectaries attracting ants that defend the plant from pests   Plant stem nodes and internodes
  • native Naturally occurring in an area, but not necessarily confined to it. Compare endemic.
  • naturalised Describing a plant, introduced from another region, that grows and reproduces readily in competition with the natural flora.
  • nectar A usually sweet, nutrient-rich fluid produced by the flowers of many plants and collected by bees and other insects.
  • nectary adj. nectariferous A specialized gland that secretes nectar.
  • neophyte A plant that has recently been introduced to a geographic area. Contrast archaeophyte.nerveAnother name for a vein.
  • node The part of a stem from which leaves or branches arise.nomen conservandum(Latin) A conserved name, usually a name that became so much better known than the correct name, that a substitution was made.nomen illegitimumA name that is either superfluous at its time of publication because the taxon to which it was applied already has a name, or the name has already been applied to another plant (a homonym).nomen invalidumA name that is not validly published, and technically is therefore not a botanical name. Abbreviation: nom. inval. See valid publication.nomen nudumA name not published in accordance with the International Code of Nomenclature for algae, fungi, and plants, usually without a diagnosis or description of the entity to which it applies, and without reference to either; such a name should not be used.
  • nomenclature The naming of things; often restricted to the correct use of scientific names in taxonomy; a system that sets out provisions for the formation and use of names.
  • noxious Of plants, containing harmful or unwholesome qualities. Applied in conjunction with 'weed' to specifically describe a plant which legislation deems harmful to the environment. Each state and territory in Australia has specific legislation governing noxious weeds.
  • nucellus The tissue of the ovule of a seed plant that surrounds the female gametophyte. It is enclosed by integuments and is not of epidermal origin.numerousStamens are described as numerous when there are more than twice as many as sepals or petals, especially when there is no set number of them. Compare indefinite
  • obcordate (of a leaf blade) Broad and notched at the tip; heart-shaped but attached at the pointed end.
  • obligate (of parasites) Unable to survive without a host. Contrast facultative.obliqueSlanting; of a leaf or stem, larger on one side of the midrib than the other, in other words asymmetrical.obloidHaving a three-dimensional oblong shape, e.g. a fruit.
  • oblong Having a length a few times greater than the width, with sides almost parallel and ends rounded.
  • obovate (of a leaf) Having a length about 1.5 times the width, and widest above the centre.obsoleteNot evident, or at most rudimentary or vestigial.obtrapeziformtrapeziform, but attached by the narrower trapezoidal base (e.g. of a leaf)obtuseBlunt or rounded; having converging edges that form an angle of more than 90°. Compare acute.
  • olim Formerly, e.g. "olim B", formerly in the Berlin herbarium (Herbarium Berolinense).
  • ontogeny The sequence of developmental stages through which an organism passes as it grows.   Opposite arrangement of leaves on the stems of a plant (see phyllotaxis)
  • operculum (calyptra)A lid or cover that becomes detached at maturity, e.g. in Eucalyptus, a cap covering the bud and formed by the fusion or cohesion of perianth parts.
  • opposite 1.  Describing leaves or flowers borne at the same level but on directly opposite sides of their common axis.2.  Describing the occurrence of something on the same radius as something else, e.g. anthers opposite sepals. Compare alternate.opus utique oppressum pl. opera utique oppressa Listed after the botanical name of a plant, or the name of a publication, this indicates that a publication is listed in the International Code of Nomenclature for algae, fungi, and plants as a suppressed work. Botanical names of the specified rank in the publication are considered not validly published (article 34).
  • order A group of one or more families sharing common features, ancestry, or both.
  • ovary The basal portion of a carpel or group of fused carpels, enclosing the ovules.ovateShaped like a section through the long-axis of an egg and attached by the wider end.
  • ovoid Egg-shaped, with wider portion at base; 3-dimensional object, ovate in all sections through long-axis.
  • pachycaul with a disproportionately thick trunkpachycladouswith disproportionately thick stems
  • palea (plural paleae) 1. the upper of two bracts enclosing a grass flower, major contributors to chaff in harvested grain.2.  Chaffy scales on the receptacles of many Asteraceae.3.  Chaffy scales on the stipe of many ferns.paleateBearing paleae or chaffy scales, as in description of the receptacle of a capitulum of a plant in the Asteraceae.paleaceousChaff-like in texture.
  • palmate 1.  leaf with veins radiating out from a central point (usually at the top of a petiole), resembling spread out fingers pointing away from the palm.2.  A compound palmate leaf has leaflets that radiate from a central point (usually at the top of a petiole).
  • palmatifid Deeply divided into several lobes arising from more or less the same level.
  • papilla   pl. papillae; adj. papillose or papillate A small, elongated protuberance on the surface of an organ, usually an extension of one epidermal cell.
  • parasite An organism living on or in a different organism, from which it derives nourishment. Some plant species are parasitic. Compare saprophyte and epiphyte.
  • parenchyma A versatile ground tissue composed of living primary cells which performs a wide variety of structural and biochemical functions in plants.parietalAttached to the marginal walls of a structure, e.g. ovules attached to placentas on the wall of the ovary. See placentation.
  • pedate Having a terminal lobe or leaflet, and on either side of it an axis curving outwards and backwards, bearing lobes or leaflets on the outer side of the curve.
  • peltate Shield-like, with the stalk attached to the lower surface and not to the margin.
  • pellucid Transmitting light; for example, said of tiny gland dots in the leaves of e.g. Myrtaceae and Rutaceae that are visible when held in front of a light.
  • pendulous Hanging, for example an ovule attached to a placenta on the top of the ovary. Compare suspended.
  • penicillate Tufted like an artist's brush; with long hairs towards one end.
  • perennating Of an organ that survives vegetatively from season to season. A period of reduced activity between seasons is usual.
  • perennial A plant whose life span extends over several years.
  • perfoliate With its base wrapped around the stem (so that the stem appears to pass through it), e.g. of leaves and bracts.perforateWith many holes. Used to describe the texture of pollen exine, and also to indicate that tracheary elements have a perforation plate. See also fenestrate.perforation platein a tracheary element, part of the cell wall that is perforated; present in vessel members but not in tracheids. Should not be confused with a pit.
  • perianth The collective term for the calyx and corolla of a flower (generally used when the two are too similar to be easily distinguishable). Abbreviation: P; for instance, P 3+3 indicates the calyx and corolla each have 3 elements, i.e. 3 sepals + 3 petals.
  • perigynous Borne around the ovary, i.e. of perianth segments and stamens arising from a cup-like or tubular extension of receptacle (free from the ovary but extending above its base). Compare epigynous, hypogynous.persistentRemaining attached to the plant beyond the usual time of falling, for instance sepals not falling after flowering, flower parts remaining through maturity of fruit. Compare deciduous, caducous.
  • perule adj. perulate 1.  The scales covering a leaf or flower bud, or a reduced scale-like leaf surrounding the bud. Buds lacking perulae are referred to as "naked".2.  In Camellias the final bracts and sepals become indistinguishable and are called perules.3.  A kind of sac formed by the adherent bases of the two lateral sepals in certain orchids.
  • petal In a flower, one of the segments or divisions of the inner whorl of non-fertile parts surrounding the fertile organs, usually soft and conspicuously coloured. Compare sepal.
  • petaloid Like a petal; soft in texture and coloured conspicuously.
  • phanerogam Gymnosperms and angiosperms; plants producing stamens and gynoecia; literally plants with conspicuous sexual reproductive organs. Compare cryptogams.
  • phenology The study of the timing of seasonal biological phenomena, such as flowering, leaf emergence, fruit ripening and leaf fall.
  • phyllode adj. phyllodineous A leaf with the blade much reduced or absent, and in which the petiole and or rachis perform the functions of the whole leaf, e.g. many acacias. Compare cladode.
  • phyllopodium (in ferns) A short outgrowth of the stem on which the frond is borne and which remains attached to the rhizome after the frond has been shed.
  • phytomelan Also phytomelanin; adj. phytomelanous A black, inert, organic material that forms a crust-like covering of some seeds, commonly found in Asparagales, Asteraceae, etc.pileateHaving a cap, a pileus.
  • pileus A cap or cap-shaped structure, such as the cap of mushrooms or the plumule of some monocotyledons.piliformHaving the shape of a cap, a pileus.pilosecovered with soft, weak, thin and clearly separated hairs, which are usually defined as long and sometimes ascending.
  • pinnate a compound leaf with leaflets arranged on each side of a common petiole or axis; also applied to how the lateral veins are arranged in relation to the main vein.
  • pinnatisect pinnately divided almost to midrib but segments still confluent.
  • pistil 1.  a single carpel when the carpels are free.2.  a group of carpels when the carpels are united by the fusion of their walls.
  • pistillate flower a flower containing one or more pistils but no stamens. Sometimes called a female flower.pistillodeA sterile or rudimentary pistil.pitIn tracheary elements, a section of the cell wall where the secondary wall is missing, and the primary wall is present. Pits generally occur in pairs and link two cells.
  • placenta The tissue within an ovary to which the ovules are attached.
  • placentation The arrangement of ovules inside ovary; for example axile, free-central, parietal, marginal, basal, or apical.
  • placodioid The form of a lichen thallus which radiates outward with the ends of the radiating arms peeling up from the substrate, but which lack a cortex on the underside (unlike foliose lichens).
  • Plant Breeders Rights (PBR)These rights, governed by Plant Breeder's Rights Acts give the plant breeder legal protection over the propagation of a cultivar, and the exclusive rights to produce and to sell it, including the right to license others to produce and sell plants and reproductive material of a registered, deliberately bred variety. Cf. UPOV.
  • Plant Variety Rights (PVR)Governed by the Plant Variety Rights the registration of new varieties is now governed by Plant Breeders Rights.
  • Plastochron The time between successive leaf initiation events.
  • plicate Pleated; folded back and forth longitudinally like a fan, such as the leaves of fan palm species. The concept often appears in specific names in forms such as Kumara plicatilis and Acacia plicata. Commonly such names are not correctly appropriate, but are applied to distichous structures rather than plicate.-plinerved(of leaves) A suffix indicating that the main nerves are lateral and arise from a point distinctly above the base of the leaf. Combined with a numerical prefix to form words like 3-plinerved, 5-plinerved, and so on. Such leaves are especially characteristic of the family Melastomataceae. See for example Dissotis.plumoseLike a feather; with fine hairs branching from a main axis.
  • pneumatophore A vertical appendage, aerial at low tide, on the roots of some plants. Pneumatophore functions are unclear, but possibly related to gas exchange, or to root anchoring. Pneumatophores typically occur on mangrove roots, but some versions occur on species of conifers, such as some in the Taxodioideae.pod1.  A legume, the fruit of a leguminous plant, a dry fruit of a single carpel, splitting along two sutures.2.  A siliqua and silicula, the fruit of Brassicaceae, a dry fruit composed of two carpels separated by a partition.
  • pollen powdery mass shed from anthers (of angiosperms) or microsporangia (of gymnosperms); the microspores of seed plants; pollen-grains.
  • polyploid with more than two of the basic sets of chromosomes in the nucleus; any sporophyte with cells containing three or more complete sets of chromosomes. Various combinations of words or numbers with '-ploid' indicate the number of haploid sets of chromosomes, e.g. triploid = 3 sets, tetraploid = 4 sets, pentaploid = 5 sets, hexaploid = 6 sets, and so on.polystemonoushaving numerous stamens; the number of stamens being at least twice the number of sepals or petals, but not strictly three or four times that number.
  • population 1.  All individuals of one or more species within a prescribed area.2.  A group of organisms of one species, occupying a defined area and usually isolated to some degree from other similar groups.3.  In statistics, the whole group of items or individuals under investigation.
  • prickle   adj. prickly A hard, pointed outgrowth from the surface of a plant (involving several layers of cells but not containing a vein); a sharp outgrowth from the bark, detachable without tearing wood. Compare thorn.
  • prophyll A leaf formed at the base of a shoot, usually smaller than those formed later.
  • pro parte In part. In nomenclature, used to denote that the preceding taxon includes more than one currently recognized entity, and that only one of those entities is being considered.
  • propagule Any structure capable of generating a new plant; includes seeds, spores, bulbils, etc.prostrateLying flat on the ground; commonly rooting at nodes that touch the soil surface.
  • protandrous Having male sex organs which mature before the female ones, e.g. a flower shedding pollen before the stigma is receptive. Compare protogynous.
  • pseudo-A prefix meaning "false, not genuine", e.g. a pseudo-bulb is a thickened, bulb-like internode in orchids, but not an actual bulb.pseudobasifixed(of an anther) Connected to the filament of the stamen by connective tissue which extends in a tube around the filament tip. See also basifixed and dorsifixed.
  • puberulous Also puberulent. Covered with minute soft erect hairs.
  • pubescent Downy; covered with short, soft hairs, especially erect hairs.pulverulentHaving powdery or crumbly particles as if pulverized.pulvinateHaving a pulvinus.
  • pulvinus a swelling at either end of a petiole of a leaf or petiolule of a leaflet, e.g. in Fabaceae, that permits leaf movement.punctate(from Latin puncta= puncture or prick-mark) marked with an indefinite number of dots, or with similarly small items such as translucent glands or tiny hollows.punctiformDot-like or in the shape of a prick-mark.pungentHaving a sharp, hard point.
  • pyramidal (of a growth habit) Conical or pyramid-shaped. Most familiar in some coniferous trees, especially species adapted to snowy climates
  • pyrene The stone of a drupe, consisting of the seed surrounded by the hardened endocarp.pyriformPear-shaped; a term for solid shapes that are roughly conical in shape, broadest one end and narrowest at the other. As a rule the distal third of their length is the broadest, and they are narrowest near the proximal end, the base, where the stalk, if any, attaches.
  • pyrophile Plants which need fire for their reproduction.
  • pyrophyte Plants which have adapted to tolerate fire.   Q   Siliques of Conringia orientalis tend towards a quadrate cross section. quadrateMore or less square. R   Bulbinella latifolia racemes, flowers already open at the bottom, while the axis still is growing and budding at the top   Rachis of Vachellia karroo bipinnate leaf, components labelled as follows: A. Rachilla (the diminutive of rachis) B. Pinnule C. Jugary glands D. Juga (plural of jugum) E. Base of petiole F. Petiolary gland G. Rachis   radicles emerging from germinating seeds   Reniform kidney bean seeds   A leaf of Ficus carica, illustrating reticulate venation   The central leaflets of the ternate leaves of Searsia glauca are oblate and commonly retuse   Typical rhizome, this one a specimen of Iris pseudacorus   Grafting Kiwifruit vine scion onto rootstock below.   Unidentified Gasteria bearing leaves with a rugose surface, banded with callosities.   Rugose leaves of Alocasia are stiffer than flat leaves of the same size and thickness would be.   Unidentified Crassula bearing rugulose leaves with fine, inconspicuous wrinkles in the epidermis
  • raceme adj. racemose, An indeterminate inflorescence in which the main axis produces a series of flowers on lateral stalks, the oldest at the base and the youngest at the top. Compare spike. Also racemiform or racemoid - having the form of a raceme
  • rachis   pl. rachises or rachides The axis of an inflorescence or a pinnate leaf; for example ferns; secondary rachis is the axis of a pinna in a bipinnate leaf distal to and including the lowermost pedicel attachment.radialWith structures radiating from a central point as spokes on a wheel (e.g. the lateral spines of a cactus).radiate(of daisies, of a capitulum) With ray florets surrounding disc florets.
  • radical Springing from the root; clustered at base of stem.
  • rainforest A moist temperate or tropical forest dominated by broad-leaved trees that form a continuous canopy.
  • recumbent bent back towards or below the horizontal.
  • recurved bent or curved backwards or downwards.reduplicatefolded outwards, or with the two abaxial surfaces together.
  • replum a framework-like placenta to which the seeds attach, and which remains after each valve drops away.
  • resupinate 1.  In botany, describing leaves or flowers that are in an inverted position because the petiole or pedicel, respectively, is twisted 180 degrees. compare: #hyper-resupinate2.  In lichenology, referring to either having or being a fruiting body that lies flat on the substrate, with the hymenium either over the whole surface or at the periphery.reticulateforming a network (or reticulum), e.g. veins that join one another at more than one point.retrorseBent backwards or downwards. Compare antrorse.
  • retuse Having a blunt (obtuse) and slightly notched apex.revisionan account of a particular plant group, like an abbreviated or simplified monograph. Sometimes confined to the plants of a particular region. Similar to a monograph in clearly distinguishing the taxa and providing a means for their identification. Compare monograph.revoluterolled under (downwards or backwards), for example when the edges of leaves are rolled under towards the midrib. Compare involute.rhachisSee rachis.
  • rhizome a perennial underground stem usually growing horizontally. See also stolon. Abbreviation: rhiz.rhizomatousadj. a plant whose above ground stem is derived from a below ground stem (rhizome). cf. arhizomatous (arhizomatic)
  • rhizosphere the below-ground surface of plants and adjacent soil as a habitat for microorganisms.rhytidomethe dead region of the bark that lies outside the periderm.rhombiclike a rhombus: an oblique figure with four equal sides. Compare trapeziform, trullate.
  • rhomboid a four-sided figure with opposite sides parallel but with adjacent sides an unequal length (like an oblique rectangle); see also rhombic.
  • rhomboidal a shape, for instance of a leaf, that is roughly diamond-shaped with length equal to width.
  • root a unit of a plant's axial system which is usually underground, does not bear leaves, tends to grow downwards, and is typically derived from the radicle of the embryo.
  • root hairs outgrowths of the outermost layer of cells just behind the root tips, functioning as water-absorbing organs.
  • root microbiome the dynamic community of microorganisms associated with plant roots.
  • rootstock 1. the part of a budded or grafted plant which supplies the root system, also simply called a stock.2.  plants selected to produce a root system with some specific attribute, e.g. a virus-free rootstock.
  • rosette when parts are not whorled or opposite but appear so, due to the contractions of internodes, e.g. the petals in a double rose or a basal cluster of leaves (usually close to the ground) in some plants.
  • rostrate with a beak.rotatecircular and flattened; for example a corolla with a very short tube and spreading lobes (for instance some Solanaceae).
  • ruderal a plant that colonises or occupies disturbed waste ground. See also weed.   The runcinate lobes of a Taraxacum officinale leaf point downwards, i.e. towards the stem rudimentIn the structure of a plant, an item that is at best hardly functional, either because it is immature and has not yet completed its development (such as a leaf still incompletely formed inside a bud), or because its role in the organism's morphology cannot be completed and therefore is futile (such as the leaf rudiment at the tip of a phyllode, that will be shed while immature, because the leaf function will be taken over by the phyllode). Compare cataphyll, vestige.rudimentaryBeing of the nature of a rudiment; at most barely functional because incompletely developed; begun, but far from completed, either temporarily or permanently. Compare vestigial.rugoseWrinkled, either covered with wrinkles, or crumpled like a wrinkled leaf, either as a stiffening structure, or in response to disease or insect damage.ruguloseFinely wrinkled.
  • ruminate (usually applied to endosperm) Irregularly grooved or ridged; appearing chewed, e.g. the endosperm in certain members of Myristicaceae.runcinateSharply pinnatifid or cleft, with the segments directed downward.runnerSee stolon.
  • rupicolous Rupestral, saxicolous, growing on or among rocks. Compare epilithic and lithophytic.rushA plant of the family Juncaceae or, more loosely, applied to various monocotyledons. S   Sagittate leaves of an Alocasia plant   Salverform flowers of Plumbago auriculata   Trametes versicolor, a saprotroph that consumes dead wood in forests. Its conspicuously patterned brackets earn it the common name "Turkey tail Fungus", but the main body of the saprotroph consists of the largely invisible mycelium that penetrates the dead wood and digests it.   Strawberry plants reproduce mainly by sarments, stolons such as these, often called runners; at their nodes the sarments put up tufts of leaves and strike root if there is any good soil beneath.   This Caloplaca marina lichen is saxicolous because it grows on stone.   Micrograph of the scabrid undersurface of the leaf of Stipa pulcherrima.   Involucral bracts of Syncarpha species are as scarious as tissue paper, but look like live petals for years, so they are known as "Everlastings" and valued for dried arrangements.   Isolated sclereid or stone cell in plant tissue   Stone cells, sclereids in gritty tissue particles in tissue of a pear.   Sepals on Geranium thunbergii, five separated behind the petals of an open flower, and a connected set enclosing an unopened bud.   Sericeous leaves of Podalyria sericea, silver sweet pea bush.   Fruit of Lepidium bonariense is a silicula, green and circular, with a notch at the apex.   Silky foliage of the silvertree: Leucadendron argenteum   Sori under the leaf of the fern Rumohra adiantiformis. Some of the sori still are covered by their indusia   Spadix of Amorphophallus maximus within its spathe. The female flowers are around the bottom of the spadix, the male flowers above, and the sterile top part is the major source of pollinator attractants.   The convolute spathe around the spadix of Zantedeschia aethiopica   Drosera spatulata leaves are markedly spathulate   The flowering spike of this Salvia nemorosa differs from a raceme in that the flowers are practically sessile.   Spines emerging from the areoles of an Echinopsis species   Spinescent leaves of Salsola australis, stiff, narrowed, and with lobes ending in spiny points.   Bird nest fungi, Nidulariaceae, bear spectacular examples of splash-cups, out of which raindrops can spread their spores.   Sporangia of the fungus Rhizopus   Staminate flowers of Shepherdia canadensis   Manilkara hexandra flowers have both stamens with anthers and staminodes that have no anthers   Subulate leaves are narrow, broadest at their base, and taper to an elongated tip, as seen on this Aloe.   Large, acaulescent, succulent, linear, cuspidate mottled leaves of the Gasteria, and the small, succulent, cordate leaves of a Crassula species, contrast with the linear, herbaceous leaves of a Hypoxis species   Suckers around the trunk of Chrysalidocarpus lutescens   Sulcate (specifically polysulcate) grooves along the stem of Scorzonera cana   Superior ovary in Aloe. Two flowers from same plant: one of them sectioned to displany the pistil and hypanthium   The suture along the concave curve of the pod of Crotalaria, along which the seeds are attached, is where the single carpel has folded shut, leaving the visible suture.   An undamaged syconium of a Ficus species, plus two syconia cut open longitudinally to display the fruit within.  
  • saccate Pouched or shaped like a sack.
  • sagittate Shaped like the head of an arrow; narrow and pointed but gradually enlarged at the base into two straight lobes directed downwards; may refer only to the base of a leaf with such lobes. Compare hastate.salverformTrumpet-shaped; having a long, slender tube and a flat, abruptly expanded limb.
  • saprophyte adj. saprophytic A plant, or loosely speaking, a fungus or similar organism, deriving its nourishment from decaying organic matter such as dead wood or humus, and usually lacking chlorophyll. Compare parasite, saprotroph and epiphyte.
  • saprotroph adj. saprotrophic An organism deriving its nourishment from decaying organic matter. Contrast parasite and epiphyte.sarmentA long, slender, prostrate stolon, commonly called a runner.sarmentoseReproducing by sarments; strawberry plants are the most familiar example.
  • saxicolous Growing on stone, like some lichens.scabrid Also scabrous. Rough to the touch, with short hard protrusions or hairs.scalariformLadder-like in structure or appearance.scale1.  A reduced or rudimentary leaf, for example around a dormant bud.2.  A flattened epidermal outgrowth, such as those commonly found on the leaves and rhizomes of ferns.
  • sclerenchyma A strengthening or supporting tissue composed of sclereids or of a mixture of sclereids and fibers.
  • sclerophyll adj. sclerophyllous A plant with hard, stiff leaves; any structure stiffened with thick-walled cells.
  • scrubland Dense vegetation dominated by shrubs.scurfMinute, loose, membranous scales on the surface of some plant parts, such as leaves.
  • secondary metabolite Chemicals produced by a plant that do not have a role in so-called primary functions such as growth, development, photosynthesis, reproduction, etc.
  • secretory tissue The tissues concerned with the secretion of gums, resins, oils and other substances in plants.
  • section (sectio)The category of supplementary taxa intermediate in rank between subgenus and series. It is a singular noun always written with a capital initial letter, in combination with the generic name.secundHaving all the parts grouped on one side or turned to one side (applied especially to inflorescences).sedgeA plant of the family Cyperaceae.
  • seed A ripened ovule, consisting of a protective coat enclosing an embryo and food reserves; a propagating organ formed in the sexual reproductive cycle of gymnosperms and angiosperms (together, the seed plants).
  • segment A part or subdivision of an organ, e.g. a petal is a segment of the corolla. A term sometimes used when the sepals and petals are indistinguishable.
  • self-pollination (also selfing) The acceptance by stigmas of pollen from the same flower or from flowers on the same plant, which means they are self-compatible.
  • senecioid See anthemoid.sensitiveA descriptive term for stigmas that, in response to touch, close the two lobes of the stigma together, ending the receptivity of the stigma, at least for the time that the lobes are closed together. Mimulus is perhaps the best-known example.
  • sensu In the sense of.sensu auct.(of a plant group or name) As cited by a named authority.sensu amplo(of a plant group or name) In a generous or ample sense.
  • sensu lato (of a plant group) In a broad sense.sensu strictissimo(of a plant group) In the narrowest sense.
  • sepal In a flower, one of the segments or divisions of the outer whorl of non-fertile parts surrounding the fertile organs; usually green. Compare petal.
  • series The category of supplementary taxa intermediate in rank between section and species. It is often used as a plural adjective, as in "Primula subgenus Primula sect. Primula series Acaules".
  • serrate Toothed with asymmetrical teeth pointing forward; like the cutting edge of a saw.
  • sheath A tubular or rolled part of an organ, e.g. the lower part of the leaf in most grasses.
  • shoot The aerial part of a plant; a stem and all of its dependent parts (leaves, flowers, etc.).
  • shrub A woody perennial plant without a single main trunk, branching freely, and generally smaller than a tree.sigmoidShaped like the letter 'S'.
  • silky Densely covered with fine, soft, straight, appressed hairs, with a lustrous sheen and satiny to the touch.
  • silviculture The science of forestry and the cultivation of woodlands for commercial purposes and wildlife conservation.simpleUndivided or unsegmented, e.g. a leaf not divided into leaflets (note, however, that a simple leaf may still be entire, toothed or lobed) or an unbranched hair or inflorescence.sinuateHaving deep, wave-like depressions along the margins, but more or less flat. Compare undulate.
  • sinus A notch or depression between two lobes or teeth in the margin of an organ.solitarySingle, of flowers that grow one plant per year, one in each axil, or widely separated on the plant; not grouped in an inflorescence.soraliaIn a lichen, the structure that bears soredium for non sexual reproduction.
  • soredium pl. soredia In a lichen, a small groups of algal cells surrounded by fungal filaments that form in soralia, which break off and grow new lichens without sexual reproduction after being dispersed by wind. Compare to an isidium, which breaks off and is dispersed by mechanical means.sorus pl. sori A cluster of sporangia. Sori typically occur in ferns, some Algae and some fungi. In many fern species the sorus is covered by a protective indusiumsp.An abbreviation of species (singular), often used when the genus is known but the species has not been determined, as in "Brassica sp." See spp.spp.An abbreviation of species (plural), often used to collectively refer to more than one species of the same genus, as in "Astragalus spp." See sp.
  • spathe   adj. spathaceous A large bract ensheathing an inflorescence. Traditionally any broad, flat blade.
  • spathulate or spatulateSpoon-shaped; broad at the tip with a narrowed projection extending to the base.
  • species A group, or populations of individuals, sharing common features and/or ancestry, generally the smallest group that can be readily and consistently recognized; often, a group of individuals capable of interbreeding and producing fertile offspring. The basic unit of classification, the category of taxa of the lowest principal rank in the nomenclatural hierarchy. Strict assignment to a species is not always possible, as it is subject to particular contexts, and the species concept under consideration.
  • specific epithet Follows the name of the genus, and is the second word of a botanical binomial. The generic name and specific epithet together constitute the name of a species; i.e. the specific epithet is not the species name.
  • spine adj. spinose A stiff, sharp structure formed by the modification of a plant organ that contains vascular tissue, e.g. a lateral branch or a stipule; includes thorns.
  • spinescent Ending in a spine; modified to form a spine.
  • spiral Of arrangement, when plant parts are arranged in a succession of curves like the thread of a screw, or coiled in a cylindrical or conical manner.
  • splash-cup (sporangia)A cup-like structure in fungi such as Nidulariaceae and in cryptogams such as some mosses. The cups function in spore dispersal, in whch the energy of raindrops falling into the cup causes the water to splash back out carrying the spores.[[[10]]]
  • sporangium (sporangia)A structure in which spores are formed. and from which the mature spores are releasedsporangiophoreAn organ bearing sporangia, e.g. the cones of Equisetum.
  • sport A naturally occurring variant of a species, not usually present in a population or group of plants; a plant that has spontaneously mutated so that it differs from its parent plant.
  • spreading Extending horizontally, e.g. in branches. Standing out at right angles to an axis, e.g. in leaves or hairs.
  • spur 1.  a short shoot.2.  a conical or tubular outgrowth from the base of a perianth segment, often containing nectar.squamule(plural squamules, squamulae) small scales; In lichens, squamules are overlapping plate-like forms, sometimes overlapping so much as to become leaf-like, but which lack a lower cortex, unlike the leafy forms of foliose lichens – adjective: squamulosesquamuloseCovered with small scales (squamules). In lichens, being composed of squamules.squarroseHaving tips of leaves, stems, etc. radiating or projecting outwards, e.g. in the moss Rhytidiadelphus squarrosus.s.t.An abbreviation for "sometimes". Compare usu. and oft.
  • stalk The supporting structure of an organ, usually narrower in diameter than the organ itself.
  • stamen   adj. staminate The male organ of a flower, consisting (usually) of a stalk called the filament and a pollen-bearing head called the anther.
  • staminode A sterile stamen, often rudimentary, sometimes petal-like.staminophoreA structure, around the apex of eucalypt, myrtaceae hypanthia, that supports the stamens.standardThe large posterior petal of pea-flowers.standard specimenA representative specimen of a cultivar or other taxon which demonstrates how the name of that taxon should be used.steleThe primary vascular system (including phloem, xylem, and ground tissue) of plant stems and roots.stellateStar-shaped.
  • stem The plant axis, either aerial or subterranean, which bears nodes, leaves, branches and flowers.stem-claspingSee amplexicaul.
  • stenospermocarpy The development or production of fruit that is seedless or has minute seeds because of the abortion of seed development. Compare parthenocarpy.
  • sterile Infertile, as with a stamen that does not bear pollen or a flower that does not bear seed.
  • stigma The pollen-receptive surface of a carpel or group of fused carpels, usually sticky; usually a point or small head at the summit of the style.
  • stipe Generally a small stalk or stalk-like structure. The stalk of a frond of a fern; the stalk supporting the pileus of a mushroom; the stalk of a seaweed such as a kelp; the stalk-like support of a gynaecium or a carpel
  • stoma pl. stomata A pore or small hole in the surface of a leaf (or other aerial organ) allowing the exchange of gases between tissues and the atmosphere.stone cella sclereid cell, such as the cells that form the tissue of nut shells and the stones of drupes.striateStriped with parallel, longitudinal lines or ridges.strigoseCovered with appressed, straight, rigid, bristle-like hairs; the appressed equivalent of hispid.
  • subgenus A category of supplementary taxa intermediate between genus and section. The name of a subgenus is a singular noun, always has a capital initial letter and is used in combination with the generic name, e.g. Primula subgenus Primula.
  • subspecies A taxonomic category within a species, usually used for geographically isolated or morphologically distinct populations of the same species. Its taxonomic rank occurs between species and variety.
  • subtend To stand beneath or close to, as in a bract at the base of a flower.subquadrangularNot quite square. Compare quadrangular.
  • subulate Narrow and tapering gradually to a fine point.
  • succulent 1.  Juicy or fleshy.2.  A plant with a fleshy habit.
  • sucker A shoot of more or less subterranean origin; an erect shoot originating from a bud on a root or a rhizome, sometimes at some distance from the stem of the plant.
  • sulcate Furrowed; grooved. May be single (monosulcate), two (bisulcate) or many (polysulcate).superficialOn the surface.superiorOf an ovary, borne above the level of attachment of the other floral parts, or above the base of a hypanthium. Contrast inferior and half-inferior.suspendedOf an ovule, when attached slightly below the summit of the ovary. Compare pendulous.
  • suture A junction or seam of union. See fissure and commissure.swardExtensive, more or less even cover of a surface, e.g. a lawn grass. Compare tussock.
  • sympatric Having more or less similar or overlapping ranges of distribution.sympodialA mode of growth in which the main axis is repeatedly terminated and replaced with a lateral branch. Examples occur in the family Combretaceae, including the genera Terminalia and Combretum. cf. monopodial
  • synaptospermy The dispersal of diaspores as units, where each bears more than one seed, for example where each diaspore comprises an entire inflorescence, as in Brunsvigia or multi-seeded fruit as in Tribulus zeyheri. Ephemeral synaptospermy is the term for when the diaspores split into units containing fewer or single seeds each, as in most tumbleweeds. True synaptospermy is when the diaspore generally remains entire until germination, as commonly happens in species of Grielum.
  • synonym An outdated or 'alternative' name for the same taxon.
  • synoecious A synonym of bisexual.syntepalousHaving fused tepals. See also sympetalous (having fused petals).   T   Leucaena leucocephala taproot exposed in a roadcut   Cross sections of Brazil nut Seeds, showing the tegmen and testa   Tendrils of Cucurbita pepo, some supporting the stem on the frame, some failing to find a point of attachment.   Nerine bowdenii, showing the lack of visible sepals, and the inferior ovaries. The sepals are incorporated into the corolla as alternate tepals   Terete raceme of Kniphofia shown together with a cross section of a peduncle. A:Inflorescence. B: Terete peduncle. C: Cross section of a terete peduncle   Gymnosporia buxifolia has true thorns, meaning that the thorns are modified branches; as shown here, in some species such branches are complete with buds and leaves   Sweet potato tubers exposed, showing them to be root tubers. Morphologically they differ from stem tubers of potatoes, for example, in that root tubers do not have nodes that bear buds. The root tubers of some species of plants however, can produce adventitious buds for vegetative reproduction   Oxalis tuberosa stem tuber. Being a stem tuber, it differs from root tubers in that the tuber has nodes that bear buds that can sprout as a means of vegetative reproduction   Corms of Crocosmia bear typical tunics formed of cataphylls growing from the nodes of the corm. The illustration show still-living cataphylls as white tissue, whereas the functional, hard, resistant tunic is brown.   Spinning-top shaped, or turbinate roots of sugar beet   Haworthia lockwoodii with its leaves turgid and green after seasonal rains, storing water against the coming dry period.   Tussock grasses on mountain slopes.  
  • taproot The primary descending root of a plant with a single dominant root axis.tartareousHaving a surface that is course, thick, rough, and crumbling.
  • taxon pl. taxa A group or category in a system of biological classification.
  • taxonomy The study of the principles and practice of classification.
  • tendril Any slender organ modified from a stem, leaf, leaflet, or stipule and used by climbing plants to cling to an object.
  • tepal A segment of a perianth, either sepal or petal; usually used when all perianth segments are indistinguishable in appearance.
  • terminal Situated at the tip or apex.ternateIn groups of three; of leaves, arranged in whorls of three; of a single leaf, having the leaflets arranged in groups of three.
  • testa The seed coat.tetradA group of four; usually used to refer to four pollen grains which remain fused together through maturity (e.g. in the Epacridaceae).[[[11]]]tetragonalSquare; having four corners; four-angled, e.g. the cross-sections of stems of herbaceous Lamiaceae.
  • theca One of the usually two synangia in which pollen is produced in flowering plants. It consists of two fused sporangia known as pollen sacs. The wall between the pollen sacs disintegrates before dehiscence, which is usually by a common slit.
  • thorn A sharp, stiff point, usually a modified stem, that cannot be detached without tearing the subtending tissue; a spine. Compare prickle.throatThe opening of a corolla or perianth.
  • thyrse A branched inflorescence in which the main axis is indeterminate (racemose) and the lateral branches determinate (cymose).
  • tomentum A dense covering of short, matted hairs. Tomentose is often used as a general term for bearing an indumentum, but this is not a recommended use.
  • trapeziform 1.  Like a trapezium (a four-sided figure with two parallel sides of unequal length).2.  Like a trapezoid (a four-sided figure, or quadrilateral, with neither pair of sides equal); sometimes used erroneously as a synonym for rhombic.
  • tree A woody plant, usually with a single distinct trunk and generally more than 2–3 metres (6.6–9.8 ft) tall.triadA group of three.
  • trichome In non-filamentous plants, any hair-like outgrowth from the epidermis, e.g. a hair or bristle; sometimes restricted to unbranched epidermal outgrowths.trifidSplit into three parts. See also bifid.trifoliateA compound leaf of three leaflets; for example, a clover leaf.
  • trimerous In three parts, particularly with respect to flowers; having three parts in each whorl. See also tetramerous and pentamerous.trinervedHaving three nerves or veins.triplinerved(of leaves) Having three main nerves with the lateral nerves arising from the midnerve above the base of the leaf.
  • triquetrous More or less triangular in cross-section, but acutely angled (with 3 distinct longitudinal ridges). Compare trigonous.trivalveDivided into three valves. Also trivalvar. See also bivalve.
  • trullate Ovate but angled, as with a bricklayer's trowel; inversely kite-shaped. Compare rhombic.truncateCut off squarely; having an abruptly transverse end.
  • trunk The upright, large and typically woody main stem of a tree.trussA compact cluster of flowers or fruits arising from one centre; evident in many rhododendrons.
  • tuber Any of many types of specialised vegetative underground storage organs. They accumulate food, water, or in protection from death by fire, drought, or other hard times. Tubers generally are well differentiated from other plant organs; for example, informally a carrot is not generally regarded as a tuber, but simply a swollen root. In this they differ from the tuber of a sweet potato, which has no special root-like function. Similarly, corms are not generally regarded as tubers, even though they are underground storage stems. Tubers store food for the plant, and also have important roles in vegetative reproduction. They generally are of two main types: stem tubers form by the swelling of an underground stem growing from a root, or from structures such as underground stolons. Stem tubers generally produce propagative buds at their stem nodes, forming a seasonal perennating organ, e.g. a potato. The main other class is the root tuber, also called tuberoid. They differ from stem tubers in features such as that, like any normal root, they do not form nodes.
  • tubercle A small wart-like outgrowth or protuberance of tissue.
  • tuberculate Covered in tubercles. See warty.tuberoidAn alternative name for underground storage organ formed by the swelling of a root; occurs in many orchids.tuberousResembling a tuber or producing tubers.tubularHaving the form of a tube or cylinder.tuftedDensely fasciculate at the tip.tunicThe outer covering of some bulbs and corms.tunicate(of bulbs) Consisting of concentric coats.turbinateShaped like a spinning top or beetroot.turgidSwollen with liquid; bloated; firm. Compare flaccid.
  • tussock A dense tuft of vegetation, usually well separated from neighbouring tussocks, for example in some grasses. Compare sward.two-rankedHaving leaves arranged in two rows in the same plane, on opposite sides of the branch. See distichous.
  • type An item (usually an herbarium specimen) to which the name of a taxon is permanently attached, i.e. a designated representative of a plant name. Important in determining the priority of names available for a particular taxon.
  • umbel A racemose inflorescence in which all the individual flower stalks arise in a cluster at the top of the peduncle and are of about equal length; in a simple umbel, each stalk is unbranched and bears only one flower. A cymose umbel looks similar to an ordinary umbel but its flowers open centrifugally.   Umbo in the middle of the cap of Cantharellula umbonata. umbo   Thorny prickles of Senegalia mellifera subspecies detinens are unciform   Mammillaria bocasana has uncinate tips to its major spines.   Pitchers of the species Nepenthes ventricosa tend to be markedly urceolate. A rounded elevation, such as in the middle of the top of an umbrella or mushroom; a central boss or protuberance, such as on the scale of a cone.umbonateHaving an umbo, with a conical or blunt projection arising from a flatter surface, as on the top of a mushroom or in the scale of a pine cone.
  • uncinate Having a hook at the apex.undershrubA low shrub, often with flowering branches that die off in winter. Compare subshrub.
  • urceolate Shaped like an urn or pitcher, with a swollen middle and narrowing top. Examples include the pitchers of many species of the pitcher plant genera Sarracenia and Nepenthes.usu.An abbreviation of usually. Compare s.t. and oft.utricle1.  A small bladder; a membranous bladder-like sac from the ovary wall, thin pericarp, becomes more or less bladdery or inflated at maturity enclosing an ovary or fruit.2.  In sedges, a fruit in which the fruit is loosely encloses from a modified tubular bract, see perigynium. V   Photomicrograph of cross section of vascular bundle in the stem of a typical herbaceous dicotyledon. A: Phloem B: Cambium C: Xylem D: Fibrous sheath of vascular bundle   Leaf veins and velutinous hairs of Nepeta   Velamen, the pale grey membrane covering the mature part of the root of an epiphyte   Flower stalks and sepal tube of Pueraria phaseoloides are covered with velutinous (velvety) hairs   Verticillaster of Perovskia atriplicifolia   Verticillate leaves and emerging branchlets of a forb   Viscum capense Detail of branch and vestigial leaf scales on some of the stem nodes   Asparagus virgatus owes its specific epithet virgatus to the twiggy appearance of its virgate shoots. vallecular canalA resin canal coinciding with a longitudinal groove in the seeds of Asteraceae. A longitudinal cavity in the cortex of the stems of Equisetum, coinciding with a groove in the stem surface.
  • valvate (of sepals and petals in bud) Meeting edge-to-edge but not overlapping.valveA portion of an organ that fragments or splits open, e.g. the teeth-like portions of a pericarp in a split (dehisced) capsule or pod when ripe.var.An abbreviation of varietas.variantA plant or group of plants showing some measure of difference from the characteristics associated with a particular taxon.
  • vasculum A container used by botanists for collecting field specimens.
  • veinlet A small vein; the ultimate (visible) division of a vein.velamenA spongy tissue covering the aerial roots of orchids and some other epiphytes.velutinousSee velvety.velvetyDensely covered with fine, short, soft, erect hairs.
  • ventral From Latin venter, meaning "belly". The opposite of dorsal. Partly because the term originally referred to animals rather than plants, usage in botany is arbitrary according to context and source. In general "ventral" refers to "the belly or lower part", but in botanical usage such concepts are not always clearly defined and may be contradictory. For example: facing towards the axis (adaxial) in referring to a lateral organ of an erect plant facing towards the substrate in any part of an erect plant, for example the lower surface of a more or less horizontal leaf (abaxial) facing towards the substrate in a prostrate or climbing plant. For more detail see dorsal.
  • vernation The arrangement of unexpanded leaves in a bud; the order in which leaves unfold from a bud.vernonioidIn the Compositae, style with sweeping hairs borne on abaxial surfaces of style branches.
  • verticillate Arranged in one or more whorls, i.e. several similar parts arranged at the same point of the axis, e.g. leaf arrangement. Compare pseudoverticillate (appearing whorled or verticillate but not actually so).verticillasterA type of pseudoverticillate inflorescence, typical of the Lamiaceae, in which pseudo-whorls are formed from pairs of opposite cymes.vesicular(of hairs) Bladder-like; vesciculous, bearing such hairs.
  • vessel A capillary tube formed from a series of open-ended cells in the water-conducting tissue of a plant.
  • vestigial Reduced in form and function from the normal or ancestral condition.
  • villous Abounding in or covered with long, soft, straight hairs; shaggy with soft hairs.
  • virgate   Diminutive: virgulate Wand-shaped, twiggy, especially referring to erect, straight stems. In mycology, referring to a pileus with radiating ribs or lines.
  • viviparous 1.  Referring to seeds or fruits which germinate before being shed from the parent plant.2.  The development of plantlets on non-floral organs, e.g. leaves. W   Watershoots   Winged seeds of Catalpa bignonioides are nearly all wing. Tufts at the tips increase aerodynamic drag, thereby improving wind dispersal.   Leaves of some species of Citrus have winged petioles   Brabejum stellatifolium is unusual among trees in its native region, in that it bears its leaves in verticillate whorls
  • warty A surface covered with small round protuberances, especially in fruit, leaves, twigs and bark. See tuberculate.
  • weed 1.  Any plant growing where it is not wanted; commonly associated with disrupted habitats. See also ruderal.2.  An unwanted plant which grows among agricultural crops.3.  A naturalised, exotic, or ecologically "out-of-balance" indigenous species outside of the agricultural or garden context, which, as a result of invasion, adversely affects the survival or regeneration of indigenous species in natural or partly natural vegetation communities.[[[14]]]wildOriginating from a known wild or purely natural habitat (wilderness).
  • whorl A ring of organs borne at the same level on an axis (e.g. leaves, bracts, or floral parts).   Senecio haworthii leaves have an unusually dense woolly coat. wing1.  A membranous expansion of a fruit or seed which aids in dispersal, for instance on pine seeds.2.  A thin flange of tissue extending beyond the normal outline of a structure, e.g. on the column of some orchids, on stems, on petioles.3.  One of the two lateral petals of a flower of subfamily Faboideae of family Fabaceae, located between the adaxial standard (banner) petal and the two abaxial keel petals.
  • woolly Very densely covered with long, more or less matted or intertwined hairs, resembling a sheep's wool. X
  • xeromorph A plant with structural features (e.g. hard or succulent leaves) or functional adaptations that prevent water loss by evaporation; usually associated with arid habitats, but not necessarily drought-tolerant. Compare xerophyte.
  • xerophyte A plant generally living in a dry habitat, typically showing xeromorphic or succulent adaptation; a plant able to tolerate long periods of drought. Compare xeromorph.
  • xylem A specialised water-conducting tissue in vascular plants. Z   Zonate markings on the leaves of a garden variety of Pelargonium zonale   Like most of the genus Pelargonium, and unlike most members of the genus Geranium, Pelargonium quercifolium bears flowers that are bilaterally symmetrical. Accordingly, because the yoke of an ox is bilaterally symmetrical, such flowers are said to be zygomorphic, which literally means "yoke-shaped".
  • zonate Having light and dark circular bands or rings, typically on leaves or flowers.
  • zygomorphic Bilaterally symmetrical; symmetrical about one vertical plane only; applies to flowers in which the perianth segments within each whorl vary in size and shape. Contrast actinomorphic and irregular.
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