Achene: a small, dry, indehiscent fruit with a thin fruit wall surrounding a single seed

Acuminate: having an apex with concave sides that gradually tapers into a sharp point

Acute: having an apex with straight sides tapering into a point with an angle of less than 90°

Agamospecies: in plants that usually reproduce asexually, a distinct form that reproduces itself faithfully, and that may have been treated as a species by some taxonomists

Alternate: of leaves, having only one leaf arise at each node

Anastomosing: fusing, e.g. of leaf veins that branch then meet and reconnect

Androecium: collectively, all of the stamens of a flower

Androgynophore: a stalk that elevates the sexual parts of a flower above the receptacle and perianth, especially in passionflowers

Annual: a plant that lives for only one year

Annular: ring-shaped

Anther: the upper portion of a stamen, which produces and releases pollen

Apex: tip or uppermost portion of a plant organ

Apiculate: having an apex that ends abruptly in a short, narrow point

Appressed: lying flat against another part, especially of hairs

Arcuate: curved like a bow; of leaf venation, having several veins that originate at the base and curve towards the apex

Aril: a fleshy structure produced at the hilum of a seed, or a fleshy coating over the whole seed

Ascending: of a stem, not erect but rising upward at an angle

Attenuate: gradually tapering to a long, thin point

Auricle: an appendage or lobe, usually paired at the base of a leaf, that is fancied to be ear-shaped

Auriculate: having auricles

Awn: a narrow extension or bristle at the apex of a leaf, sepal or bract

Axil: the angle formed by the juncture between a stem and a petiole or lateral branch

Axillary: arising from a leaf axil; lateral

Basal: of the base or arising from the base; of leaves, those that are produced at ground level rather than on the stem

Base: the lower part of an organ, nearest the ground or the point of attachment to other structures

Basionym: the first published name from which a plant’s specific epithet is derived

Berry: a fleshy fruit, derived from a compound ovary or a solitary carpel, with more than one seed and without a pit

Biennial: a plant that grows vegetatively for one year, then flowers and dies in its second year

Bifid: split into two parts or lobes, especially at the apex of an organ

Bilabiate: of a calyx or corolla, bilaterally symmetrical with a two-lipped appearance (e.g., many mint flowers)

Bilaterally symmetrical: divisible into equal, mirror-image halves only along one plane; also called “irregular” or “zygomorphic”

Biotype: a population or group of populations sharing genetic or morphological features that distinguish them from other members of their species

Bipinnately compound: of leaves, pinnately compound with the main divisions of the leaf themselves pinnately divided into leaflets (often written as “2-pinnate”; tripinnately compound leaves have three orders of division)

Biserrate: of leaf margins, having two sizes or grades of serrate teeth, with large teeth that themselves have toothed margins

Blade: the main portion of a leaf or leaflet, usually broadened and flattened

Bract: a leaflike or scalelike structure that subtends a flower or an inflorescence or a branch thereof

Bracteole: a small bract subtending an individual flower; term usually used only when larger bracts are found elsewhere in the inflorescence

Bulb: a short, compact underground stem with thick, fleshy scales or leaves developed as storage organs (e.g., an onion)

Calyx: the sepals collectively, especially when fused

Cambium: in a stem or root, a ring of cells one layer thick that divides repeatedly to produce tissues; a vascular cambium separates secondary xylem from secondary phloem

Campanulate: of a fused calyx or corolla, bell-shaped

Capitate: head-like; of an inflorescence, with flowers tightly clustered and arising near the same point

Capitulum: a head; the characteristic inflorescence of the composite family, consisting of disk and/or ray florets clustered on a receptacle, subtended by a calyx-like involucre of bracts (phyllaries), the whole resembling a single flower

Capsule: a dry fruit, derived from a compound ovary, with a thin wall that splits at maturity to release the seeds

Carpel: a simple pistil, or a unit of a compound gynoecium, formed of one modified leaf, with a unilocular ovary, style (usually) and stigma; multiple carpels may fuse to create a compound pistil

Carpophore: in the carrot family, a stalk extended from the receptacle to which the two carpels (developing into mericarps) are attached at the bifid apex

Cartilaginous: with a firm but pliable texture, like cartilage

Catkin: a small, dense spikelike inflorescence consisting of reduced unisexual wind-pollinated flowers, without perianth and subtended by bracts

Cauline: referring to the stem; of leaves, borne on the stem (in contrast to basal leaves)

Ciliate: of leaves, sepals etc., having hairs along the margin

Clasping: of a leaf base, with projections that wrap around the stem

Claw: especially of petals, a sharply narrowed, stalk-like base

Commissure: in fruits of the carrot family, the attachment of the two mericarps to one another by the sides facing the carpophore; the plane along which the mericarps separate in most species

Compound: made up of more than one part

Compound leaves: leaves divided into multiple leaves rather than a single simple blade

Compound ovary: the lower portion of a pistil deriving from the fusion of several carpels; may have one large round locule, or as many locules as carpels

Compound umbel: the typical inflorescence of the carrot family, an umbel of rays each bearing a terminal umbellet of flowers

Cone: a reproductive structure in gymnosperms, in which ovules are borne naked on protective bracts, rather than enclosed in an ovary as in all flowering plants

Cordate: heart-shaped, with the broad notched end basal

Coriaceous: leathery

Corolla: the petals collectively, especially when fused

Corona: used to refer to a variety of “crown-shaped” structures, such as an extra whorl of colorful filaments between the petals and the stamens (in passionflowers), an ornate reproductive structure (in milkweed relatives), or a pappus consisting of a ring-shaped ridge or scale atop the fruit (in the composite family)

Cortex: a ring of parenchymatous tissue inside the epidermis or bark, and outside the vascular tissue, of a stem or root

Corymb: a branching inflorescence with a flat top, with the outermost flowers maturing first

Cosmopolitan: occurring nearly worldwide (within habitat restrictions); refers to a plant that is widely distributed on several continents

Crenate: of leaf margins, having rounded teeth

Crenulate: crenate, with the teeth small

Crisped: of leaf margins, wavy in a plane perpendicular to the surface of the leaf

Cuneate: wedge-shaped; tapering with straight sides

Cuspidate: terminating abruptly with a short sharp point; similar to apiculate

Cyme: a branching inflorescence with the terminal flower maturing first, sometimes complex in shape

Cymule: a small cyme, often a segment of a larger inflorescence

Cypsela: a dry, single-seeded fruit resembling an achene, but derived from an inferior ovary thus having an extra layer of tissue as part of the fruit wall; characteristic of the composite family

Dehiscent: of a fruit, remaining intact rather than splitting open to release seeds

Deltoid: broadly triangular, with the base being one of the flat sides

Dentate: having outward-pointing teeth on the margins

Denticulate: dentate, with the teeth small

Dioecious: having unisexual flowers, with the sexes borne on different plants (as contrasted with monoecious)

Disk floret: in Asteraceae, a radially symmetrical flower, often borne on the central portion of the receptacle of a capitulum (as contrasted with ray florets)

Distal: of the end of a part or organ that is farthest from its attachment to the rest of the plant (contrasted with proximal)

Drupe: a fleshy fruit, with each seed surrounded by a hard endocarp (pyrene), often one-seeded with a large pith (e.g., an olive)

Elliptical: oval, broadest in the middle, narrower above and below the middle

Endemic: native only to a specified area, not found in the wild elsewhere

Endocarp: the innermost layer of a fruit wall (pericarp), sometimes differentiated, e.g. into a hard protected layer

Endosperm: nutritive tissue contained inside a seed

Entire: of leaf margins, continuous and straight, without teeth or lobes

Epicalyx: a whorl of bracts beneath a flower that resemble a calyx, especially in the cotton family

Epidermis: the outermost layer of cells of young or non-woody plant organs

Erect: standing upright

Exocarp: the outermost layer of a fruit wall (pericarp)

Follicle: a dry fruit, derived from a single carpel, that splits along one side to release seeds

Filament: usually, the sterile stalk of a stamen, which bears the anther

Funiculus: the stalk by which a developing seed is attached to the placenta in the ovary

Funnelform: especially of fused corollas, funnel-shaped, gradually tapering toward the base

Fusiform: of three-dimensional structures; spindle-shaped, widened in the middle

Glabrate: almost glabrous, very sparsely hairy

Glabrous: hairless, not pubescent

Glaucous: glabrous and with a waxy coating

Globose: roughly spherical

Gynobasic: of a style, arising at the center and from the base of a deeply lobed compound ovary (e.g. in many mints)

Gynoecium: collectively, all of the carpels of a flower, whether separate or fused into a compound pistil

Half-inferior: of an ovary, often used to refer to the ovary of a flower that has a hypanthium but in which the hypanthium is not fused to the ovary (hence, the ovary is visible and not truly inferior)

Hastate: of leaf bases, shaped like an arrowhead with outward-pointing basal lobes

Head: a capitulum, an inflorescence in which many flowers are borne in a tight cluster at the end of the peduncle; in the composite family, often having both ray and disk florets and resembling a single flower

Hermaphroditic: of flowers, possessing both male and female sexual organs; also called perfect or bisexual

Hilum: the scar that is left on a seed when it separates from the funiculus

Hypanthium: a tube formed by complete fusion of the basal parts of the calyx, corolla and filaments, ranging from very short to cup-shaped to elongated and tubular, often fused also to the sides of the ovary (which is then inferior)

Indehiscent: of a fruit, not splitting open to release seeds

Inferior: of an ovary, having the lowermost portions of the other floral whorls fused to the sides of the ovary so that only the top of the ovary is visible inside the flower and the ovary appears to be embedded in the receptacle, with the free portions of the other whorls apparently borne above it

Inflorescence: all of the flowers borne on a single flowering axis

Intercalary: of an inflorescence, produced on the stem below the apex, with more vegetative growth above

Internode: a segment of a stem between branches or leaves

Involucre: a whorl of bracts subtending or surrounding a flower or group of flowers

Keel: a longitudinal ridge down the center of a bract or sepal; in many legumes, two petals that form a shape fancied to resemble the keel of a boat

Lanceolate: shaped like the head of a lance, broader below the middle; narrower than ovate

Lateral: at or of the side; of a flower or inflorescence, borne along the stem, usually arising from leaf axils, rather than at the tip of the stem

Lax: of a branching inflorescence such as a panicle, open and flexible with space between flowers rather than crowded and stiff

Legume: a dry fruit, produced from a single carpel, that dehisces along both sides; characteristic of the bean family

Lenticel: a porous structure in bark that permits gas exchange through the otherwise airtight cork; may be a slit or a small bump

Ligule: a strap-shaped organ; in the composite family, the flattened corolla of a ray floret

Limb: in a petal with a narrowed base (claw), the wider, spreading apical portion; in a fused corolla with a tubular base, the widened upper portion

Linear: very narrow with parallel margins

Lobate: having lobed margins

Lobe: of leaves, a division or protrusion too large to be considered a tooth, often rounded; of a calyx or corolla that is fused basally, the upper free portion of a sepal or petal

Locule: the hollow chamber within an ovary that contains ovules; a simple carpel has only one locule, while compound ovaries (formed by the fusion of several carpels) may have one large locule or may be divided into single locules

Loculicidal: of a capsule, splitting open in the middle of locules, in contrast to splitting along the septa between locules (i.e., septicidal)

Margin: the outside edge of a leaf, sepal, petal, etc.

Medullary rays: rays of parenchyma that separate vascular bundles in a stem, also called pith rays

Mericarp: a single-seeded, separately dispersed segment of a schizocarp, derived from a single carpel, as in the carrot family

Mesocarp: the middle layer of a fruit wall, the layer that becomes thick and fleshy in berrylike fruits

Micropyle: a pore or opening in the coat of a seed, the point of entrance of the fertilizing pollen tube

Microspecies: in confusing variable genera, a form or population that has been given a species name but is at best marginally distinct

Midrib: the central vein in a leaf, running from the base to the apex, usually larger than other veins

Monoecious: having unisexual flowers, with both sexes borne on the same plant, often in separate inflorescences (compare to dioecious)

Mucronulate: having a minute bristlelike narrow point at the tip

Nectary: a structure that produces nectar, usually but not always inside the corolla of a flower

Node: a point on a stem at which one or more leaves and/or branches are produced

Nothospecies: a plant of hybrid origin that is named and treated as a species

Nutlet: in plants such as mints with a gynobasic style, a small dry fruit derived from one of the lobes of the ovary

Obcordate: heart-shaped, with the broad notched end basal

Obdeltoid: broadly triangular, with the base being one of the points

Oblanceolate: like lanceolate, but with the broadest portion above the middle

Oblique: of a leaf base, asymmetrical, often with one side tapering to narrowly rounded and the other side rounded to cordate

Oblong: somewhat rectangular, with straight parallel sides, and the breadth at, above, and below the middle nearly equal

Obovate: like ovate, but broadest above the middle

Obtuse: having a blunt apex, forming a point with an angle of >90°, or somewhat rounded

Opposite: of leaves, borne two per node on opposite sides of the stem

Orbicular: roughly circular in outline, as broad as long

Ovary: the lowest part of a carpel or pistil, containing one or more ovules

Ovate: egg-shaped, broadest below the middle

Ovoid: egg-shaped, referring to a three-dimensional structure

Ovule: structure inside an ovary that develops into a seed after the egg cell borne inside is fertilized

Paleae: bracts borne on the receptacle of a composite head (capitulum), subtending individual disk florets

Palmate: of leaflets, leaf lobes or veins, arising radially from the base like fingers from a hand

Panicle: a branching inflorescence with the lower flowers maturing first (compare to a raceme, which is not branched)

Papilla: a small bump or wart on the epidermis

Papillate: bearing papillae

Pappus: in composite florets, a modified calyx that may be present at the top of the ovary and persisting on the fruit, usually consisting of one or more whorls of bristles, a scale, or a small ring of tissue (e.g., the fluffy portion of a dandelion “seed”).

Parenchyma: soft, thin-walled, unspecialized plant tissue

Pedicel: a stalk on which a single flower is borne

Peduncle: the stalk or stem on which an inflorescence is borne

Pellucid: transparent, clear, like some leaf glands

Peltate: of leaves or trichomes, umbrella-like in shape with the stalk attached not at the edge, but on the lower surface

Pepo: characteristic fruit of the cucumber family, derived from an inferior ovary, with a tough rind, fleshy mesocarp, and numerous seeds

Perennial: a plant that normally lives for at least three years

Perfect: of flowers, possessing both male and female parts; also called bisexual or hermaphroditic

Perianth: collectively, the calyx and corolla, including all sepals and petals or all tepals

Pericarp: fruit wall, including all layers of tissue derived from the ovary

Pericycle: in roots, a small amount of parenchyma found at the outside of the initial vascular cylinder; in older and larger roots, the pericycle may give rise to a large cortex-like ring of parenchyma between the vascular tissue and the bark (“secondary cortex”)

Petaloid: resembling a petal, often colorful

Petiole: a stalk on which the blade of a leaf is borne

Petiolule: the stalk of an individual leaflet in a compound leaf

Phloem: nonwoody vascular tissue that transmits sugars downward; in large woody stems or roots, a ring of secondary phloem is produced outside the secondary xylem (wood); in woody stems, secondary phloem is the innermost layer of the inner bark

Phyllary: in the composite family, a bract in the involucre subtending the entire capitulum (contrast with palea, a bract borne on the capitulum’s receptacle and subtending a single floret)

Pinnate: of compound or lobed leaves or leaf venation, feather-like with a single main axis, with leaflets, lobes or smaller veins emerging at points along the axis and extending laterally

Pinnatifid: of a leaf, deeply pinnately lobed or cleft, but the clefts between lobes not reaching the midrib

Pinnatisect: of a leaf, pinnately lobed with the clefts between lobes extending to the midrib, but the lobes not forming clearly separate leaflets as in a pinnately compound leaf

Pistil: the entire gynoecium where multiple carpels are fused together, or the only carpel in a unicarpellate gynoecium

Pith: an area of soft parenchymatous tissue inside the vascular tissue at the center of a stem or rhizome, or rarely a root

Ploidy: the number of copies of each chromosome within a single cell, e.g., diploid (2 copies, as in almost all higher animals), tetraploid (4 copies), or hexaploid (6 copies); plants of different ploidy levels usually cannot reproduce successfully, so change in ploidy often results in speciation

Plumose: with long, soft pinnately branching bristles that give a feathery appearance

Prickle: a sharp outgrowth of the epidermis of a stem, as in roses

Primary venation: the midrib of a pinnate-veined leaf or the few main veins arising from the base of a palmate-veined leaf

Prostrate: of a stem, creeping along the ground, sprawling

Proximal: of the end of a part or organ that is closest to its attachment to the rest of the plant (contrasted with distal)

Pubescent: bearing hairs (trichomes); sometimes refers especially to short, soft hairs

Punctate: dotted with round depressions or glands

Pyrene: a pit or stone of a drupe, consisting of a hard layer of fruit tissue (endocarp) surrounding a single seed

Raceme: an unbranched inflorescence with pedicellate flowers, the lower flowers maturing first (compare to a panicle, in which the rachis is branched, or to a spike, in which the flowers are sessile)

Rachis: the central stalk of a compound leaf or the stalk of an inflorescence above the point of attachment of the first leaflets or flowers

Radially symmetrical: divisible into equal, mirror-image halves along multiple planes, as in a roundish flower with all petals of equal size and shape; also called actinomorphic or regular

Radicle: the part of an embryo that will develop into the primary root

Ray floret: in the composite family, a floret with an asymmetrical, flattened corolla resembling a single petal, often borne only near the edge of the receptacle of a head; also called ligulate florets

Receptacle: the tissue at the base of a flower from which the perianth and sexual organs arise; in composite heads, the knob of tissue at the end of the peduncle on which the florets are borne

Reflexed: bent backward or downward, e.g., petals that curve toward the pedicel

Reniform: kidney-shaped

Reticulate: of leaf veins, net-like or forming a network

Revolute: of leaf margins, inrolled or folded over toward the underside, somewhat like a tiny hem

Rhizome: an underground stem, often resembling a root

Rhomboid: diamond-shaped, with obtuse angles at the sides and acute angles at the base and apex

Rosette: a whorl of leaves arising at ground level

Rotate: especially of a fused corolla, disk-shaped or wheel-shaped

Samara: a dry, indehiscent, single-seeded fruit, with the fruit wall forming a wing

Scape: a leafless peduncle arising from ground level

Scarious: of bracts, sepal margins, etc., dry, membraneous or papery, not green

Schizocarp: a dry fruit that at maturity splits into a number of sections (mericarps) equalling the number of carpels that formed the gynoecium

Scutellum: in Scutellaria, an asymmetrical protrusion on the calyx, fancied to be shield-shaped

Secondary venation: leaf veins arising directly from the midrib or primary veins

Section: a taxonomic rank below subgenus; a named portion of a genus

Sensu stricto: in the narrow sense, if there is taxonomic controversy about how broadly the boundaries of a species should be drawn

Septate: divided by septa

Septum: a partition, especially the tissue separating locules in a compound ovary

Serrate: having sharp, forward-pointing teeth like a saw blade

Serrulate: serrate, with the teeth small

Sessile: of a leaf or flower, borne directly attached to a stem rather than elevated on a petiole or pedicel

Seta: a very short bristle

Silicle: characteristic of the mustard family, a dry, dehiscent fruit, flattened with a central membrane (replum) to which seeds are attached, which persists after the outer wall of the fruit falls away; if fruit length is more than double the breadth, it is called a silique

Simple: of leaves, trichomes, etc., not compound or branched

Sinuate: with strongly wavy margins

Solitary: of flowers, borne singly

Spatulate: of leaves, spoon-shaped, rounded at the apex and tapering to a narrow base (e.g. dandelion)

Spike: an unbranched inflorescence with sessile flowers, the lower flowers maturing first

Spreading: extending at right angles to a main axis, e.g., petals extending straight outward from the center of a flower

Stamen: a male reproductive organ, usually consisting of a sterile stalk (filament) and a fertile anther

Staminode: a sterile stamen, sometimes modified to serve some other function, or simply reduced in a female flower

Stele: the central cylinder of vascular tissue, including xylem and phloem, in a stem or root

Stellate: star-shaped; of hairs, branching, with each hair having several arms, giving a bushy appearance

Stigma: the receptive tissue at the top of a carpel or pistil, where pollination occurs

Stipe: a stalk on which a plant organ is elevated, e.g., raising the ovary above the receptacle

Stipules: a pair of small bractlike or leaflike structures borne at the base of a petiole in some flowering plants

Stolon: a horizontal, creeping stem that produces roots at nodes

Striated: bearing parallel lines not conspicuous enough to be called ridges

Style: a stalk by which the stigma is often elevated above an ovary

Stylopodium: in fruits of the carrot family, a disk-shaped enlargement of the base of the style, visible at the top of the fruit

Sub-: prefix indicating subordinate rank when preceding a taxonomic rank (e.g., subfamily), indicating “almost” or “nearly” when preceding an adjective (e.g., subsessile)

Subgenus: a named portion of a genus; a taxonomic rank between genus and section, so that one subgenus may be divided into multiple sections

Subglobose: almost spherical

Suborbicular: almost round

Subsessile: almost sessile, sometimes with very short petiole or pedicel

Subspecies: a named portion of a species that is genetically or morphologically distinctive and geographically separated from other subspecies; of a higher rank than variety, so that one subspecies may be divided into multiple varieties

Tepal: individual unit of a perianth in which there is only one whorl of parts, or in which sepals and petals are identical (as in a tulip)

Terete: cylindrical, circular in cross-section

Terminal: borne at the end of a stem (contrast to lateral, borne at the side of a stem, often emerging from a leaf axil)

Ternate: divided into threes, especially of compound leaves

Tertiary venation: leaf veins arising from secondary veins; tertiary and higher-order veins are usually smaller and weaker than primary and secondary veins

Thyrse: a dense panicle with cymose branches

Trichome: hair; an outgrowth of the epidermis, single-celled or multicellular, sometimes bearing a gland

Trifoliolate: with three leaflets (also “trifoliate”)

Truncate: of a leaf apex or base, broad and flat, as if cut off

Tuber: a thickened underground stem serving as a storage organ (such as a potato)

Tubercle: a small warty protrusion

Tubular: of a fused calyx or corolla, forming a narrow cylinder

Umbel: an inflorescence with the petioles of all flowers radiating from a single point at the end of the peduncle

Umbellet: the terminal umbels of a compound umbel

Undulate: wavy-margined, but not so much as sinuate

Unisexual: of a flower, having fertile parts of only one sex

Vallecula: in fruits of the carrot family, the area between two longitudinal ribs on the dorsal surface; usually sunken in dried fruit, forming a “little valley”, but often shallow in fresh or rehydrated fruit

Valve: a split in a capsule-like fruit that allows seeds to escape; in multilocular fruits, there is normally one valve per locule

Verticillaster: characteristic of the mint family, an inflorescence of condensed axillary cymes that appears to be a dense whorl of flowers at a node

Verticillate: whorled

Vitta: in fruits of the carrot family, an oil tube running longitudinally through the fruit wall; vittae are usually found in the valleculae between ribs on the back side and in the commissural face

Whorl: a ring of parts borne at about the same level on a stem or receptacle

Whorled: of leaves, having three or more borne at each node

Xylem: water-transporting tissue; secondary xylem in stems and roots forms wood