quincuncial: of aestivation in a flower, a variant of imbricate, such that one sepal (e.g.) have one edge outside the adjacent sepal and the other inside, two sepals have both edges inside, and two sepals have both edges outside, cf. cochleate, contorted, contortiplicate, crumpled, decussate.
quinones: the general name for aromatic compounds that have two atoms of hydrogen replaced by two atoms of oxygen, usually yellow, red, or orange, see anthraquinones, benzoquinones, hydroquinones, naphthoquinones.
quinque- (prefix) = five of whatever is qualified by the prefix.
raceme: an indeterminate inflorescence, the axis producing a series of flowers on lateral pedicels, the oldest at the base and the youngest at the top, adj. racemose, for variants, see botryoid, corymb, fascicle, raceme, spadix, spike, thyrse, umbel, cf. cyme.
radicle: the basal continuation of the hypocotyl of an embryo or seedling that gives rise to the root system of the adult plant (see taproot), sometimes more or less abortive, cf. coleoptile, coleorhiza, collet, cotyledon, eophyll, epiblast, epicotyl, mesocotyl, plumule, primary leaf, scutellum.
rank: used when organs such as leaves are arranged in vertical series (distichous = two-ranked, etc.); also used to refer to the degree of branching.
rank: in the taxonomic hierarchy, one of the levels assigned to plant groups; these denote relative inclusion relationships, e.g. a family will include a genus or genera, but not vice versa; members of the one rank are not equivalent other than - one hopes - all being monophyletic and are therefore not really comparable; for the main ranks mentioned here, see class, order, family, genus, species (which may well not be monophyletic...).
ray: (anatomy) in xylem or phloem, a vertically elongated band of often radially elongated parenchymatous cells traversing the conducting elements, see tile cells, also heterogeneous, homogeneous and heterocellular, homocellular.
ray (inflorescence): of a compound umbel, one of the first series of branches of the inflorescence axis.
receptacle: the axis of a flower on which the perianth, androecium and gynoecium are borne; in Asteraceae, used to refer to the often swollen and apically flattened part of the stem bearing the flowers and inflorescence bracts.
receptacular epigyny: of epigyny, when the floral apex is initially convex, but after gynoecial initiation the periphery of the floral apex expands and raises, forming a basin in the center of which the carpels are borne and on the periphery of which the perianth members and androecium are borne, i.e. epigyny is due to development of axial tissues (Kuzoff et al. 2001), cf. appendicular epigyny.
reduced: anther wall development in which the primary parietal layer gives rise to two secondary parietal layers, the outer producing the endothecium only, the inner producing the tapetum only, cf. basic, dicotyledonous, monocotyledonous, reduced.
reiteration: of plant architecture, when the characteristic construction of the individual is repeated by branch systems that develop on a plant after damage, or sometimes as the result of natural causes.
reniform = kidney-shaped.
resupinate: of floral symmetry, twisted through 180o, e.g. as with the ovary of many Orchidaceae; note that resupination may result in the flower maintaining an inverted (as in Orchidaceae) or "normal" position (as in Thunbergia mysorensis - see Bell & Bryan 2008).
reticulate: forming a network.
reticulate: a term used to describe the surface of a pollen grain, a network-like pattern consisting of lumina or other spaces wider than 1µm bordered by elements narrower than the lumina, whether pilae (retipilate) or muri, cf. baculate, echinate, fossulate, gemmate, foveolate, pilate, lophate, psilate, rugulate, scabrate, striate, verrucose.
reticulodromous: of leaf venation, pinnate venation (camptodromous in particular), in which the secondary veins lose their identities towards the margin as they branch repeatedly, cf. brochidodromous, eucamptodromous in particular, also cf. acrodromous, actinodromous, campylodromous, craspedodromous, dichotomous, flabellate, parallelodromous, semicraspedodromous, simple-craspedodromous.
retipilate: referring to the surface of a pollen grain whose sculpturing is made up of pilae arranged in a reticulate pattern, cf. baculate, echinate, fossulate, gemmate, foveolate, pilate, lophate, psilate, reticulate, rugulate, scabrate, striate, verrucose.
retuse: of the apex of any laminar structure, e.g., petal, leaf blade, very blunt, slightly notched and divided less than 5% the length of the structure, cf. emarginate, lobed in particular, cf. also acute, attenuate, acumen, apiculum, arista, awn, cuneate, caudate, cuspidate, mucronate, muticous, obtuse, rounded, truncate, cf. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).
revolute: of leaf ptyxis, more or less flat, but the each margin independently curved abaxially, cf. circinate, conduplicate, conduplicate-flat, conduplicate-involute, conduplicate-plicate, curved, flat, involute, plicate, supervolute, supervolute-curved, supervolute-involute.
rheophyte: a narrow-leaves plant, usually a shrub, growing in or by rivers and periodically subject to immersion in fast-flowing waters, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, suffrutescent, schopfbaum, shrub, subshrub, tree, vine, see also life forms.
rhipidium: of a monochasial cymose inflorescence of some monocots, flowers arising successively from the adaxial prophylls, thus alternating from one side of the axis to the other side, and all being in a single plane, the whole inflorescence often appearing corymbose from a lateral view, cf. drepanium, helicoid cyme, scorpioid cyme.
rhizoid: unicellular trichomes on the collar in seedlings, especially those of monocots; basically precocious roothairs, but longer, denser, and/or living longer, but of course also different in position.
rhizome: a slender to much swollen underground stem that grows more or less horizontally, cf. bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, runner, stolon, tuber, tiller, turion.
rhombic: a term used for outlines and plane shapes, with length:breadth ratio 2:1 - 3:2, widest and more or less angled at the middle, pointed at the apex and base, see broadly, broad-transverse, narrowly, transverse, cf. elliptic, obovate, ovate, triangular, trullate.
ribose: a sugar.
root: commonly thought of as one of the three basic parts of the seed plant body, that part of the axial system which is usually underground and more or less positively geotropic, does not bear leaves and only rarely shoots, is endogenous in origin, indeterminate in growth and often with secondary thickening, see root cap, root tip and root hair, see also fibrous root, hair root, magnolioid root, nodule, tap root, and tuberous root; roots are sometimes arranged in distinctive clusters, see coralloid, dauciform and proteoid root clusters, see also primary and secondary root systems, also pneumatophore and pneumathode. Cf. leaf and stem (the other main parts of the seed plant body), also the cross zone, cf. also rhizoid.
rosette leaves: the leaves at the base of the stem when these are separated by very short internodes and lie more or less flat on the ground, so forming a circle, see also basal and radical leaves, cf. cauline.
rosoid: a leaf tooth in which the central vein terminates subapically and there is a large clear glandular foramen, two straight higher-order secondary veins also terminate in the foramen, cf. begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, salicoid, spinose, theoid, urticoid, violoid.
rostellum: in orchids, the (as stipes [hamulus, tegula], viscidium) apical portion of the median stigmatic lobe, sometimes used to refer only to the modified non-receptive part (see Rasmussen 1982), for other commonly-used terms specific to orchid flowers, see caudicula, column, incumbent, labellum, sectile, and stipes, also epichile, hypochile.
rostrum (rostrate) = beak (beaked).
rotational: on of the basic types of symmetry, identity of two figures after rotation of the first, thus the flowers of Vinca show a 5-fold rotational symmetry achieved after bringing the five asymmetrical corolla lobes sequentially to the upper (or other invariant) position, cf. reflectional and translational.
rounded: of the shape of the apex or base in particular, without any angles and generally convex in apperance, cf. acute, attenuate, acumen, apiculum, arista, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, truncate, cf. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).
rugose: deeply wrinkled, dim. rugulose, with minute wrinkles.
rugulate: a term used to describe the pollen surface, with elongated sexine elements more than 1µm long arranged in an irregular pattern intermediate between reticulate, retipilate and striate, cf. also baculate, echinate, fossulate, gemmate, foveolate, pilate, lophate, psilate, scabrate, verrucose.
runcinate: deeply lobed and with the lobes slanted away from the apex, cf. acute, attenuate, acumen, apiculum, arista, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, cf. also cordate, hastate, oblique, sagittate (esp. of lamina base).
runner: rather vague, often used to refer to some kind of slender stem, in particular to a stem not bearing roots between the rooted plants, whether or not made up of one or more internodes, cf. bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tuber, tiller, turion..
saccate = pouched.
sagittate: shaped like an arrow-head, cf. acute, attenuate, acumen, apiculum, arista, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, cf. also cordate, hastate, oblique, runcinate (esp. of lamina base).
salicoid: a leaf tooth in which the medial vein ends in dark but not opaque persistent spherical callosity, no laterals are involved, perhaps close to a theoid tooth, cf. also begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, spinose, urticoid, violoid.
salicylic acid: orthohydroxybenzoic acid, obtained from the bark of the white willow and wintergreen leaves, its salts are the salicylates.
salverform: e.g. of a polysymmetric corolla, salver- or trumpet-shaped, like the corolla of Primula with a long, slender tube and abruptly expanded flat, spreading limb (rotate in one sense), cf. campanulate, rotate, infundibular, tubular, urceolate.
sapromy[i]ophilous: a kind of entomophilous pollination, flowers pollinated by flies and with a distinctive syndrome (e.g. flowers/flower-like inflorescences large, purplish color, with the odour of carrion or of decay in general, thermogenic), cf. cantharophilous, melittophilous , myophilous, psychophilous, sphigophilous.
scabrate: a term used to describe the pollen surface, ornamented in any way with elements less than 1µm in all directions, cf. baculate, echinate, fossulate, gemmate, foveolate, pilate, lophate, psilate, reticulate, retipilate, rugulate, striate, verrucose.
scale: a rather vague term, usually a thin flap of tissue of epidermal origin, e.g. at the base of a stamen in Simaroubaceae.
Schisandra-type: an embryo sac type, the types based on variation in megasporogensis and megagametogenesis, unisporic (from the chalazal cell), 4-celled, all cells haploid, cf. Adoxa, Allium, Drusa, Endymion, Fritillaria, Oenothera, Penaea, Peperomia, Plumbagella, Plumbago, Polygonum, Schisandra.
schizo- (prefix): split.
schizocarp: a dry, dehiscent fruit formed from more than one carpel and breaking apart septicidally into 1-carpellate units (mericarps) when ripe, these containing one (or more) seeds, cf. capsule, follicle, lomentum.
schopfbaum: of habit, an unbranched woody plant less than about 10 m tall and often with a rather stout trunk and a tuft of large leaves at the top, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, shrub, subshrub, suffrutescent, tree, vine, see also life forms.
sclereid: a dead cell that is a component of sclerenchyma, variously shaped but usually at most only moderately elongated and with a strongly lignified wall, cf. fibre, see astrosclereid, filiform sclereid, brachysclereid, macrosclereid, osteosclereid, trichosclereid.
scorpioid cyme: a monochasial cymose inflorescence branching alternately from a bracteole/prophyll on one side of a pedicel and then from one on the other side, the flowers being borne in two rows, the whole more or less zig-zag but also coiled like the tail of a scorpion, cf. drepanium, helicoid cyme, rhipidium.
scutellum: a special term applied to the more or less shield-shaped and absorbtive haustorium at the end of the cotyledonary hyperphyll in the embryo or seedling of grasses (i.e. the term haustorium itself would really do), of a monocot seedling, see also < href="glossaryi_p.php#mesocotyl">mesocotyl, coleorhiza, hyperphyll (apocole, /scutellum, phanomer), hypophyll (cotyledonary sheath, coleoptile), collar (epiblast, periblast).
secondary metabolite: a rather misleading term referring to compounds not involved in photosynthesis, respiration and other basic metabolic activities of the cells.
secondary wall: that part of the cell wall deposited during late expansion growth of the cells with strengthening, etc., functions, and made up of cellulose fibrils, lignin, etc., cf. middle lamella, plasmodesmata, primary wall.
sectile: in Orchidaceae, refering to the soft and friable - "mealy" - texture of some pollinia made up of massulae - for other commonly-used terms specific to orchid flowers, see caudicula, column, hamulus, incumbent, labellum, rostellum, stipes, tegula, viscidium, also epichile, hypochile.
seed: a propagating organ formed in the reproductive cycle of gymnosperms and angiosperms, derived from the ovule and usually consisting of a protective seed coat (rarely absent) formed from the integument or integuments (see hilum, micropyle, linea fissura) and enclosing an embryo and often also food reserves (endosperm, primary endosperm or perisperm), see also aril, arillode, caruncle, coma, elaiosome, strophiole, ("appendages").
seedling: the young plant that results from germination of the seed, see apical hook, collet, cotyledon, eophyll, epicotyl, hypocotyl, plumule, primary leaf, radicle, of a monocot seedling, see also mesocotyl, coleorhiza, hyperphyll (apocole, haustorium/scutellum, phanomer), hypophyll (cotyledonary sheath, coleoptile), collar (epiblast, periblast).
segment: a part or sub-division of a structure.
semelparous: of reproduction, when there is just a single episode of flowering in the life of an individual, cf. iteroparous, plietesial, cf. more from the point of view of meristem persistence hapaxanthic, monocarpic, pleonanthic, and of plant duration, annual, biennial, ephemeral, perennial.
semicraspedodromous: pinnate venation, craspedodromous in particular, in which the secondary veins branch just inside the margin, one of the branches terminating at the margin, the other joining the superadjacent secondary vein, cf. simple craspedodromous in particular, also cf. acrodromous, brochidodromous, campylodromous, eucamptodromous.
semitectate: pollen in which the sexine forms a incomplete roof over the columellae, granules or other infratectal elements, the tectum in outer view often forming a reticulate pattern, cf. atectate, tectate.
senescence: age-related processes that signal the beginning of the death of a plant or plant part.
sepaloid: looking like sepals, e.g. of bracts, when green and arranged in a ring beneath a flower.
septifragal: of the dehiscence of a capsule (including schizocarps), with the valves or backs of the carpels breaking away leaving the septae intact, cf. circumscissile, loculicidal, poricidal, septicidal.
seriate: in rows or whorls, often used as a suffix, as in 2-seriate, biseriate, etc.
sericeous: of indumentum, silky in appearance, covered with silky hairs, cf. arachnoid, arbuscular, canescent, hirsute, hispid, lepidote, puberulous, pubescent, tomentose, T-shaped, villous, see also glabrescent and glabrate, which refer to stages in the loss of these hairs.
serrulate: finely serrate.
sesquiterpene lactones: lactones, subclass of C15 terpenoids (= sesquiterpenoids, sesquiterpenes), bitter-tasting and toxic, derived via the mevalonate pathway from three C5 isopentenyl pyrophosphate units.
seta: a bristle or stiff hair, setaceous, setiferous (bearing setae), setose, dim. setulose.
shoot apical meristem (SAM): a group of pluripotent cells at the apex of a stem from which stems, leaves and reproductive structures differentiate, see corpus, tunica (a histological zonation in angiosperms and Gnetales).
short-day: of a photoperiodic response, where short periods of light alternating with long periods of dark are neeeded for flowering to occur (more accurately, a long uninterrupted period of dark), cf. long-day.
short shoot: a shoot in which the internodes elongate little or at all, bearing reproductive structures and/or leaves, when well developed, as in Ginkgo and some apples, rather spur-like, cf. long shoot, the comparison often being made between axillary shoots; see also proliferation.
shrub: of habit, a woody plant less than five metres high, either without a distinct main axis, or with branches persisting on the main axis almost to its base, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, schopfbaum, subshrub, suffrutescent, tree, vine, see also life forms.
sieve cell: a conducting cell in phloem tissue of gymnosperms, elongated, nucleate, and not necessarily derived from the same mother cell that produces the closely associated Strasburger cell, the sieve areas being relatively unspecialised and the pores apparently filled with membranes that are continuous with smooth endoplasmic reticulum in the adjacent cytoplasm, there also being a central cavity in the area of the middle lamella, cf. sieve element and sieve plate.
sieve element: a cell in phloem tissue of angiosperms, that is elongated, enucleate, with P[phloem]-protein, sieve tube plastids, and a sieve plate; derived from the same mother cell that produces the closely associated companion cell, cf. sieve cell, see sieve tube.
sigmoid: doubly curved in opposite directions like the letter S.
siliceous: containing silica (SiO2).
simple aperture: of pollen where the aperture consists of a single component in one layer of the wall, cf. compound aperture, see colpate, porate, sulcate, sulculate, trichotomosulcate, ulcerate and zona-aperturate, also heterocolpate, a mixture of the two!
simple-craspedodromous: of pinnate venation, a variant of craspedodromous in which the secondary veins and their branches terminate at the margins, often as teeth, cf. semicraspedodromous in particular, also cf. acrodromous, actinodromous, brochidodromous, eucamptodromous, reticulodromous.
simple fruit: a fruit that is made up of two or more connate carpels or from a single carpel, e.g. as in Fabaceae, Asteraceae, etc., etc., i.e., fruit made up of a single unit (although this seems a singularly unhelpful definition, even by the standards of fruit terminology), cf. accessory fruit, aggregate fruit, multiple fruit.
simultaneous: of microsporogenesis where cell wall formation occurs only at the second meiotic division, the resultant tetrads being tetrahedral, walls developing by centripetal furrowing, sometimes associated with trichotomosulcate pollen, cf. successive.
siphonostele: a variant of a stele in which the central vascular column is medullated, i.e. has pith, see amphiphloic, ectophloic, cf. atactostele, eustele, dictyostele (this is a dissected amphiphloic siphonostele!), protostele.
skotophilic: lit. "dark loving".
spathella: as in some Podostemaceae, a small, closed membranous sac which envelopes the immature flower, rupturing irregularly as the pedicel elongates at anthesis.
spathulate (= spatulate): spoon-shaped; broad at the tip and narrowed towards the base.
species: a taxon comprising one or more populations of individuals capable of interbreeding to produce fertile offspring and not so interbreeding with other species, or a group of organisms phenetically distinguishable from other such groups, or...., the lowest major rank of the taxonomic hierarchy, cf. class, family, genus, order.
sphingophilous: of entomophilous flowers pollinated by hawk moths, often with a distinctive syndrome (long tube, spreading lobes, whitish color, sweet scent, etc.), cf. cantharophilous, melittophilous , myophilous, psychophilous, sapromyophilous.
spike: a racemose inflorescence, unbranched, the flowers sessile, adj. spicate, cf. botryoid, corymb, fascicle, raceme, spadix, thyrse, umbel. Note that the inflorescence of grasses like barley (Hordeum), etc. are not spikes in the strict sense, since the flowers are borne on congested lateral branches.
spinose: a leaf tooth in which the principal vein projects beyond the non-glandular apex, cf. begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, theoid, urticoid, violoid.
spiral: of leaves or floral organs, all borne singly at different levels on the axis, the insertion points of successively initiated structures forming a spiral, cf. alternate, bijugate, decussate, distichous, opposite, pseudoverticillate, spiromonistichous, tristichous, whorled.
spiromonistichous: of leaves or floral organs, borne in a single rank in a spiral along the axis, cf. alternate, bijugate, decussate, distichous, opposite, pseudoverticillate,spiral, tristichous, whorled.
split lateral: of the nodal anatomy of some plants with opposite leaves, where traces departing from the central vascular cylinder at the midpoints between the two leaves divide into two, one part proceeding to each of the leaves, cf. multilacunar, trilacunar, unilacunar, see also flank bridges.
spodogram: literally "ash letter", the mineral cystoliths, etc., remaining after calcining a leaf.
sporangium: a structure within which spores are formed, pl. sporangia, in seed plants, see anther and its thecae (really synangia) in turn made up of endothecium, exothecium, placentoid, and tapetum, all of a microsporangium, and also the nucellus + megaspore(s), both of a megasporangium, part of an ovule; for vascular plants in general, see the two basic kinds, eusporangium/giate and leptosporangium/giate.
spore: a haploid reproductive structure produced after meiosis marking the end of the sporophytic phase of the life cycle, germinating to produce the gametophyte, see megaspore and microspore/pollen (kinds of spores) and endosporic and exosporic (development of spores).
sporopollenin: the most highly decay- and chemical-resistant biopolymer known, made up of cross-linked phenolics and hydrocarbons that covers pollen grains in particular and embryophyte spores in general (but not the megaspore in flowering plants).
sport = mutant.
spur: a tubular pouch at the base of a perianth part, often containing nectar
staminal corona: in Apocynaceae-Asclepiadoideae, fleshy outgrowths of tissue, attached abaxially to the staminal column at the bases of the filaments or on the backs of the anthers, see gynostegial corona.
starch: a more or less coiled-chain polysaccharide made up of alpha glucose units, see amylose and amylopectin, and staining black with an iodine/potassium iodide solution, cf. amyloid, callose, cellulose, hemicellulose, inulin, pectin, polyol.
staurocytic: of stomata, with four (three to five) subsidiary cells each oblique to the long axis of the guard cells, cf. actinocytic, allelocytic, anisocytic, anomocytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, parallelocytic, stephanocytic, tetracytic.
stegmata: SiO2-containing cells usu. adjacent to vascular tissue, the wall adjacent to the underlying sclerenchyma thick, the anticlinal walls thinner, and the outer periclinal wall thinnest; the term rarely used when the cells are epidermal.
stele: a column of primary vascular tissue in the root and stem and any tissue that it surrounds, cf. cortex, epidermis, see atactostele, eustele, protostele (of which actinostele, haplostele, and plectostele are variants), siphonostele (of which a dictyostele, amphiphloic siphonostele and ectophloic siphonostele are variants), also polystely.
stellate: star-shaped, e.g. of a hair, cf. colleter, collar rhizoid, dendritic, malpighiaceous, T-shaped hair, also used to describe indumentum, cf. arachnoid, arbuscular, canescent, glabrescent, glabrous, hirsute, hispid, lepidote, puberulous, pubescent, sericeous, tomentose, villous.
stem: commonly thought of as one of the three basic parts of the seed plant body, that part of the axial system which bears leaves and buds and flowers; it is usually above ground and more or less negatively geotropic, exogenous in origin, often indeterminate in growth and often with a lateral meristem, made up of node and internode (see also phytomer), cf. leaf, root (the other main parts of the seed plant body - see also the cross zone), approximately = caulome, cf. phyllome. For variants (mostly more or less herbaceous) of stems, see bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tuber, tiller, turion.
stem-based: a way of defining a clade in which the basal part of an internode on a cladogram is the defining point, e.g. the clade consisting of A and all organisms that share a more recent common ancestor with A than with B, cf. apomorphy-based, node-based.
steno- (prefix): narrow.
stephanocytic: of stomata surrounded by four or more weakly differntiated subsidiary cells, cf. actinocytic, allelocytic, anisocytic, anomocytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, parallelocytic, staurocytic, tetracytic.
steroids: a large class of organic compounds characterized by a nucleus of 17 carbon atoms in the form of four fused rings (three containing six carbon atoms and one containing five), derived from triterpenes, and with varying substituents and degrees of unsaturation, including sterols, cardiac-active glycones, bufadienolides, cardenolides, and some sapogenins and alkaloids; see phytoecdysteroids..
sterols: terpenoids, solid, unsaturated steroid alcohols with an -OH group at the C3 position (bottom left below) that occur both free and as esters or glycosides, and are classified according to the organism in which they are found as mycosterols, phytosterols, etc.
stipes: in Orchidaceae, a structure derived from the rostellum to which the pollinium is attached - for other commonly-used terms specific to orchid flowers, see caudicula, column, hamulus, incumbent, labellum, massulae, sectile, stipes, tegula, viscidium, also epichile, hypochile.
stipule: one of (usually) a pair of appendages at the bases of leaves in many broad-leaved angiosperms, the term not used for monocot leaves, cf. hyperphyll, lamina, leaf base, petiole, see interpetiolar, intrapetiolar, sheathing.
stolon: a more or less slender, prostrate or trailing more or less above-ground stem which produces roots and sometimes erect shoots at its nodes, cf. bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, rhizome, runner, tuber, tiller, turion.
stomata: a pore, especially a pore in the epidermis of a leaf or other aerial organ surrounded by two guard cells and often also with subsidiary cells, providing for gaseous exchange between plant tissues and the atmosphere (pl. stomata), formed from a meristemoid, see actinocytic, allelocytic, anisocytic, anomocytic, brachyparacytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, staurocytic, stephanocytic, tetracytic (classification based on morphology, can be further elaborated), also mesogenous, mesoperigenous, perigenous (classification based on development, can be elaborated) and amphistomatic, epistomatic, and hypostomatic (position on leaf surfaces); see also lenticel, pneumathode, and pneumatophore, other structures that facilitate gas exchange.
stomium: the region of a sporangium in/down/along which dehiscence occurs, e.g. of an anther in flowering plants, including structural attributes that change over the course of anther ontogeny to give rise to the dehiscence region (see Hufford & Endress 1989, p. 303), pl. stomia, for fern sporangia, see annulus.
Strasburger cell: a nucleated cell in phloem tissue of gymnosperms that is closely associated with a sieve cell; the metabolisms of the two are intimately connected such that one cell will die soon after the other, but the albuminous cell is not necessarily derived from the same mother cell that produces the sieve cell, cf. companion cell.
striate: with several parallel longitudinal lines or ridges, often rather fine and close and separated by groves cf. costate, sulcate, cf. also (of the pollen surface) baculate, echinate, fossulate, gemmate, foveolate, pilate, lophate, psilate, reticulate, retipilate, rugulate, scabrate, verrucose.
strigose: of indumentum, with sharp, stiff hairs which are appressed to the surface; strigulose, minutely strigose, cf. arachnoid, arbuscular, canescent, glabrescent, glabrous, hirsute, hispid, lepidote, puberulous, pubescent, sericeous, stellate, tomentose, T-shaped, villous.
style: an elongated part of a carpel or group of fused carpels between the ovary and the stigma, more particularly, a single such structure of a syncarpous gynoecium, down which the pollen tubes grow, arising in the gynobasic, lateral or terminal positions, cf. stylodium, stylulus.
sub- (prefix) = nearly, almost, or under.
suberin: cell wall component made up of poluphenolic element with appreciable hydroxycinnamic acids and their derivatives and also a glycerol-bridged polyester network, occuring in e.g. endodermis and cork.
subshrub: of habit, a low shrub, sometimes with partly herbaceous stems, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, schopfbaum, shrub, suffrutescent, tree, vine, see also life forms.
subsidiary cells: epidermal cells that are clearly differentiated from the others and that immediately surround the guard cells of the stomata, q.v. for the various distinctive arrangements of these cells.
subtending: of position, one structure that is immediately below (abaxial to) another, typically of a leaf subtending a branch, or a bract subtending a flower.
subulate: narrow and tapering gradually to a fine point.
successive: of microsporogenesis, where cell wall formation occurs after the first and again after the second meiotic divisions, the resultant tetrads being mostly tetragonal, wall development normally via centrifugal plates, cf. simultaneous.
successive cambia: of secondary thickening where a series of vascular cambia alternating with conjunctive tissue are initiated sequentially from a master cambium, each one cutting off phloem externally and xylem internally, as well as other tissues, cf. included phloem, internal phloem.
suffrutescent: of habit, a plant with a herbaceous upper part and woody lower part, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, schopfbaum, shrub, subshrub, tree, vine, see also life forms.
sulcate: of pollen grains with elongate, simple apertures (ectoaperture), "latitudinal ... situated at the distal or proximal pole of a pollen grain" [Punt et al. 2007: p. 68 - would this not be longitudinal if at the poles?], cf. colpate, colporate, porate, pororate, sulculate, trichotomosulcate, ulcerate and zona-aperturate.
sulculate: of pollen grains with elongate, simple latitudinal apertures (ectoaperture) not situated at the poles, cf. colpate, colporate, porate, pororate, sulcate, trichotomosulcate, ulcerate and zona-aperturate.
superior: of an ovary, borne above the level of attachment of the other floral parts, or above the attachment of a hypanthium that is free from the ovary and itself bears the perianth segments and stamens, cf. inferior, see also epigynous, hypogynous, perigynous.
supervolute: of leaf ptyxis, both sides very strongly curved adaxially, one margin overlapping the other, cf. circinate, conduplicate, conduplicate-flat, conduplicate-involute, conduplicate-plicate, curved, flat, involute, plicate, revolute, supervolute-curved, supervolute-involute.
supervolute-curved: of leaf ptyxis, very strongly curved adaxially, but the edges not overlapping, cf. circinate, conduplicate, conduplicate-flat, conduplicate-involute, conduplicate-plicate, curved, flat, involute, plicate, revolute, supervolute, supervolute-involute.
supervolute-involute: of leaf ptyxis, strongly curved adaxially, but the very margins each strongly incurved, so not overlapping, cf. circinate, conduplicate, conduplicate-flat, conduplicate-involute, conduplicate-plicate, curved, flat, involute, plicate, revolute, supervolute, supervolute-curved.
suspensor: a part of the proembryo and derived from the basal cell of the two-celled embryo, often a single file of cells developing at the micropylar end and terminated by the basal cell, not contributing to the embryo proper, cf. hypophysis.
suture: a line of junction between two fused organs, sometimes also a line of dehiscence.
sym- (prefix): together, often indicating fusion.
symmetry: indicating the relationships of the various parts of a structure about its axis, see asymmetric, disymmetric, haplomorphic, monosymmetric (see bilabiate, papilionoid, personate, slit-monosymmetric), oblique, and polysymmetric for the terms used to describe the symmetry relationships of a flower to the axis that subtends the floral axis, reflectional, rotational and translational symmetries, the basic symmetry classes, and abaxial, adaxial, lateral, and median for the terms used to describe the relationship of one part of the flower relative to the axis of that flower, see also resupinate.
sympodial: of growth, without a single, persistent growing point, the apical meristems aborting or being converted into flowers and growth being continued by axillary buds that successively replacing the terminal buds, of a stem, growing in the above manner, see also cymose, determinate, cf. monopodial.
syn- (prefix): together, often indicating fusion, as in syncolpate pollen grains.
syncarpous: a gynoecium having two or more carpels, more or less congenitally fused together, cf. apocarpous, or syncarpous s. str., carpels mutually united and each closed on the adaxial side, i.e. the whole forming a septate ovary, cf. paracarpous, pseudomonomerous.
syndrome: a distinctive combination of features, often used in the context of fruit dispersal and flower pollination, whether or not (the latter is usual) any one of those features is unique to or even constant in a particular syndrome.
synergids: part of the egg apparatus, two cells at the apex of the embryo sac that are closely associated with the egg cell and directly involved with the process of fertilisation and often with distinctive filiform apparatus, cf. also antipodals, central cell, polar nuclei, see also egg apparatus and germ unit.
synflorescence: the complete flowering region of a shoot, see coflorescence, enrichment zone, florescence, paraclade - a set of terms for describing the architectural units making up the flowering part of a shoot, cf. inflorescence.
syntropous: of the curvature of an ovule with respect to the carpel margin that bears it, curvature in the same direction to the curvature of the margin, i.e. of carpel closure, cf. antitropous, see also apotropous, epitropous, pleurotropous.
tannins: complex, aromatic compounds (phenolics) that precipitate proteins occurring especially in the bark of many shrubs and trees, varying considerably in chemical composition and with different biosynthetic pathways and so a term of little use, see rather proanthocyanidins, hydrolyzable tannins; tanniniferous, producing tannins.
taproot: the main descending root of a plant that has a single, dominant root axis derived from the radicle of the seedling, often notably wider than the lateral roots, cf. fibrous root, hair root, magnolioid root, nodule and tuberous root.
tectum: the layer of sexine which forms a roof over the columellae, granules or other infratectal elements, cf. baculum, pilum; in tectate pollen the roof is more or less complete, cf. atectate, semitectate, cf. also foot layer and supractectal structures.
tegula: in orchids, a stalk to which the pollinia are attached that is derived from the epidermis of the rostellum; for other terms specific to orchid flowers, see caudicula, column, hamulus, incumbent, labellum, sectile, stipes, viscidium, also epichile, hypochile.
tenuinucellate: an ovule in which no cell layers separate the megasporocyte(s)/embryo sac from the epidermis, cf. crassinucellate, incompletely tenuinucellate, nucellar cap, nucellar endothelium, nucellar pad, weakly crassinucellate (different degrees of development of the nucellus or the epidermis covering it).
terminal: of a flower or bud at the apex of the stem and not immediately subtended by a leaf, also commonly used to describe general inflorescence position, cf. axillary, cauliflorous, ramiflorous, supraaxillary.
terpenes, terpenoids: usually hydrophilic compounds originating from isopentenyl and dimethyallyl pyrophosphates, consist of one isoprenoid skeleton or of a polymer made up of several such units, substituent groups may have varying degrees of oxygenation, e.g. alcoholic, ketonic, etc., subdivided according to number of carbon atoms, see cardenolides, diterpenes, monoterpenes, sesquiterpenes, triterpenes, steroids, saponins, cardiac glycosides, an immensely diverse group.
testa: that part of the seed coat that develops from the outer integument, or from the single integument when there is only one, commonly divided into the exotesta (outer epidermis), endotesta (inner epidermis), and mesotesta (the cells between), see multiplicative, cf. tegmen.
tetra- (prefix): four of whatever is qualified by the prefix.
tetracytic: of stomata, surrounded by four subsidiary cells, two or which are parallel to and two (often smaller) at right angles to the long axis of the guard cells, cf. actinocytic, allelocytic, anisocytic, anomocytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, parallelocytic, staurocytic, stephanocytic.
tetrad: a group of four things, e.g. four pollen grains remaining joined together after meiosis at maturity, cf. monad, massulae, polyad, and pollinia, see simultaneous, successive (patterns of wall formation), tetragonal, tetrahedral (arrangement of spores in tetrad), see monolete, trilete (for pollen grains of ferns, etc., that lack true apertures), also acalymmate, calymmate (exine organization), also Fisher's rule and Garside's rule.
thallus: a more or less flattened vegetative body of a plant that is not differentiated into organs such as stems and leaves, e.g. the gametophytes of many hepatics and all hornworts (cf. protonema), the plant body of flowering plants such as podostems and Araceae-Lemnoideae.
theoid: a leaf tooth in which the medial vein ends in an expanded and opaquely congested apex, no laterals are involved, cf. begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, spinose, urticoid, violoid.
thermogenesis: respiratory heat production, whether by the mediation of alternative oxidases (catabolizing lipids) or by uncoupling proteins (carbohydrates) in some variants of entomophilous pollination.
therophyte: of life forms, plants that have no resting buds as such, but which persist as seeds, loosely synonymous with annual, cf. chamaephyte, cryptophyte (see geophyte, helophyte, hydrophyte), hemicryptophyte, phanerophyte, see also habit.
thigmo- (prefix): touch.
three-ranked: organs borne singly but in three distinct ranks up the stem (orthostichies), also as tristichous, cf. one-ranked, spiromonistichous, two-ranked (distichous), also bijugate, decussate, opposite, pseudoverticillate, spiral, whorled.
throat: towards the top of a corolla tube, generally where it broadens and joins the lobes.
thyrse: of an inflorescence, branched, the main axis indeterminate and the lateral branches determinate, i.e. with a terminal flower or as a cyme, cf. panicle in particular, cf. also botryoid, corymb, fascicle, raceme, spadix, spike, umbel.
tiglic acid: a hemiterpenoid (C5 H8), trans-2-methyl-2-butenoic acid, an unsaturated fatty acid with an isoprene skeleton, posssibly not biogenetically related to the terpenoids, more probably derived from leucine.
tiller: in grasses (see Poaceae), sedges, rushes, etc., a term for a erect or ascending shoot produced at the base of the stem, often/sometimes in the axils of scale leaves, see also culm, cf. bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tuber, turion.
tilosomes: often distinctively branched masses of cellulosic and/or ligneous material coming from the inner periclinal wall in the innermost cells of the velamen adjacent to the passage cells in the exodermis, esp. in Orchidaceae.
tomentum: of indumentum, a covering of dense, matted, woolly hairs, adj. tomentose; tomentellous, minutely tomentose, cf. arachnoid, arbuscular, canescent, hirsute, hispid, lepidote, puberulous, pubescent, sericeous, stellate, villous, see also glabrescent and glabrate, which refer to stages in the loss of these hairs.
toothed: of leaf margins, a general term in the characterisations including projections described as biserrate, dentate, repand, serrate, and undulate, and also situations where the leaf blade seems to lack obvious projections of teeth, but there are small blackish points along the margin, for details of tooth morphology, see begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, spinose, theoid, urticoid, violoid.
tortuous: irregularly and more or less spirally twisted.
tracheid: a capillary tube formed from a series of dead cells in the xylem, or a single such cell, water conducting and relatively broad, where at least the primary cell wall of the end walls remains intact, cf. fiber tracheid, libriform fibre, the three making a continuum of forms, cf. also vessel, see wide-band tracheid.
transfer cells: metabolically active cells with labyrinthine inpushings of the walls (see the filiform apparatus), often found in association with vascular tissue (in phloem they are a type of companion cell, cf. intermediary cell); in seeds such cells are apparently involved in the short-distance transfer of solutes and forming a physiological bridge between the apoplast and the symplast, in the embryo sac they are prominent in the synergids.
translational: on of the basic types of symmetry, of something like a frieze that can be divided by straight lines - horizontal, vertical, etc. - into a sequence of identical figures, cf. reflectional and rotational.
translator: a narrowed often thread-like part of a pollinarium derived from stigmatic secretions that connects the corpusculum with the pollinia, as in Apocynaceae - Asclepiadoideae, cf. also viscidium; in Orchidaceae a similar structure is called the caudicula/caudicle.
transseptal bundle: in floral anatomy, the vascular bundles to the ovules in a fully syncarpous gynoecium that do not run up the ovary in the axial tissue, but they are found in the ovary wall, curving over at the apex and finally supplying the ovules, cf. dorsal bundle, ventral bundle.
transverse(ly): a qualifier of terms used for outlines and plane shapes when the length:breadth ratio is 4:5 - 1:2, cf. broadly, broad-transverse, narrowly, the terms qualified being elliptic, obovate, oblong, ovate, rhombic, triangular, trullate.
tree: of habit, a woody plant at least 5 metres high, with a main axis the lower part of which is usually unbranched, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, schopfbaum, shrub, subshrub, suffrutescent, vine, see leptocaul, pachycaul, see also life forms.
tri- (prefix): three of whatever is qualified by the prefix.
triangular: a term used for outlines and plane shapes, with length:breadth ratio 2:1 - 3:2, the base more or less straight, the sides converging to the apex, see broadly, broad-transverse, narrowly, transverse, cf. elliptic, obovate, ovate, rhombic, trullate.
trichotomosulcate: of pollen grains with simple apertures that are triradiate with longish arms, usually centred on the distal end of the grain and often occuring in monocots with simultaneous cell divisions during sporogenesis, cf. colpate, colporate, porate, pororate, sulcate, sulculate, ulcerate and zona-aperturate.
trifid: deeply divided into three parts.
trifoliolate: having three leaflets.
trilacunar: of of nodal anatomy in angiosperms, where three leaf gaps are left in the central vascular cylinder when corresponding numbers of leaf traces depart, cf. multilacunar, split lateral, unilacunar, see also flank bridges.
trilete: the triradiate or Y-shaped scars on the proximal poles of pollen (actually, prepollen) representing the points of junction of the pollen tetrads, they are weakened areas involved in germination, not occuring in angiosperms, cf. monolete.
tristichous: of leaves, arranged singly in three vertical rows along the stem (orthostichies), three-ranked, cf. two-ranked (distichous), one-ranked (monistichous), spiromonistichous, cf. also alternate, bijugate, decussate, opposite, pseudoverticillate, spiral, whorled.
tristylous: a variant of heterostyly in which there are flowers of three different kinds in the one species, in each plant all flowers have styles of only one of the three possible lengths (short, mid, long), the stamens being in two whorls of the two complimentary lengths, cf. distylous.
triterpenoids: largest single class of terpenoids, the basic structure made up of 30 carbon atoms from six isoprene units), found in resin, cutin, cork, and occurring as glycosides, see limonoids, cardenolides, quassinoids, cucurbitacins, saponins, sterols.
trullate: a term used for outlines and plane shapes, with length:breadth ratio 2:1 - 3:2, broadest below the middle, rhombic, with the two lower equal sides equal and shorter than the two equal upper sides, shaped like a bricklayer's trowel, see broadly, broad-transverse, narrowly, transverse, cf. elliptic, obovate, oblong, ovate, rhombic, triangular.
truncate: with an abruptly transverse end, as if cut off, cf. acute, attenuate, acuminate, apiculate, aristate, awned, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, cf. also cordate, hastate, oblique, runcinate, sagittate (esp. of anther or lamina base).
L-tryptophane: aromatic, hydrophobic, neutral, non-polar amino acid.
T-shaped: distinctive shape of some hairs when viewed from the side, can be unicellular (and then often called malpighiaceous) or multicellular, cf. colleter, collar rhizoid, dendritic, root hair, stellate.
tuber: a storage organ formed by swelling of an underground stem (typically) or roots (then root tuber is best), hence tuberous, or more generally swollen and not necessarily applied specifically to stems (or roots), see tuber-like, cf. bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tiller, turion.
tubercle: a small wart-like outgrowth, hence tuberculate, covered with tubercles.
tumid: swollen or inflated.
turbinate = top-shaped, obconical.
turion: an over-wintering vegetative bud or specialised short shoot with modified leaves, arising from the stem, often near ground level, also in some water plants, etc., cf. bulb, bulbil, caudex, corm, creeping stem, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tuber.
two-ranked: organs borne singly but in two distinct ranks up the stem (orthostichies), often as distichous, cf. one-ranked, spiromonistichous, three-ranked (tristichous), cf. also bijugate, decussate, opposite, pseudoverticillate, spiral, whorled.
L-tyrosine: an amino acid. a non-protein amino acid, aromatic, polar, hydrophobic.
ulcerate: of pollen grains with a single simple aperture (an ectoaperture) that is polar, rounded, and pore-like (see also ulcus, pl. ulci), cf. colpate, porate, pororate, sulcate, sulculate, trichotomosulcate, and zona-aperturate.
-ule (suffix): a diminutive, a term so qualified is small.
umbel: a raceme inflorescence, all the individual flower stalks arising in a cluster at the top of the peduncle and of about equal length, a compound umbel is an umbel of umbels, as in Apiaceae, see rays, cf. botryoid, corymb, fascicle, raceme, spadix, spike, thyrse.
umbellule: secondary umbel in a compound umbellate inflorescence.
uncinate: terminating in a hooked point.
uni- (prefix): one of whatever is qualified by the prefix.
unilacunar: of of nodal anatomy in angiosperms, where one leaf gap is left in the central vascular cylinder when the single leaf trace departs, cf. multilacunar, split lateral, trilacunar, see also flank bridges.
unilateral: e.g. of stamens, with anthers grouped on one side of the style.
unilocular: of an ovary, anther or fruit, having only one internal cavity, no matter how many basic units (carpels, sporangia) make it up.
unisexual: bearing only male or only female reproductive organs, used for the gametophyte only.
urceolate: e.g. of a polysymmetric corolla, urn-shaped, the mouth narrowed, cf. campanulate, rotate, infundibular, salverform, tubular. (the lobes are rather more spreading than is usual in such corollas).
urticoid: a leaf tooth in which the medial secondary vein terminates in a non-glandular apex, there are also higher-order convergent lateral veins, cf. begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, spinose, theoid, violoid.
utricle: a small bladder; a small, bladdery, more or less inflated, dry, single-seeded fruit, a variant of achene s.l., sometimes the fruit itself is surrounded by an appendicular structure, see perigynium s. str., cf. caryopsis, cypsela, nut.
vascular bundle: aggregations of phloem (usually abaxial in the leaf and towards the outside in the stem) and xylem (vice versa), sometimes with associated transfusion tissue and with a variety of sheaths (mestome sheath, parenchyma sheath, starch sheath), see amphicribral, amphiphloic, amphivasal, bicollateral, collateral, ectophloic (tissue arrangement) and closed, open (potential for development of vascular cambium).
vascular cambium: a lateral meristem developing from the fascicular and interfascicular cambium and which cuts off xylem to the outside and phloem to the inside, with fusiform initials and ray initials, see storied, cf. cork cambium, cuticular epithelium, polyderm.
vascular tissue: conducting tissues made up of xylem and phloem, see also hadrom(e), leptom(e), stereom(e) (the three major parts of such tissue), in the stem often as a vascular cylinder (see also stele), surrounded by the cortex and surrounding the pith, cf. epidermis, ground tissue, periderm.
vegetative reproduction: a rather confusing term, sometimes referring to reproduction that does not involve the production of seeds (as used here), sometimes to all reproduction that does not involve normal meiosis and fertilisation, i.e. apomixis s.l., cf. amphimixis.
venation: the arrangement of veins in a leaf, see palmate, parallel, pinnate (general types), acrodromous, brochidodromous, campylodromous, craspedodromous, dichotomous, eucamptodromous, flabellate, parallelodromous, semicraspedodromous, simple-craspedodromous (particular types), see also fimbrial and intramarginal veins, areoles and paxillate venation.
ventral: of a lateral organ, of the side towards the subtending axis in early development, so it is sometimes used to refer rather counter-intuitively to the upper surface of a leaf blade, however, the term is also used in the opposite sense, so it is very confusing, = adaxial, cf. dorsal.
ventral bundle: in floral anatomy, the vascular bundle running up the middle of the carpel wall, between the septae and not asssociated with the placentae, "the midrib bundle of the carpellary leaf", cf. dorsal bundle, transseptal bundle.
ventricidal: in fruit dehiscence, when the opening is along the inner or ventral (= adaxial) side of a carpel; this is a curious term, since if applied to a fruit made up of a single carpel, then it is equivalent to a cf. follicle, so it can really be applied only to a syncarpous fruit, and in such cases where individual carpels have separated septicidally they are then described as opening adaxially.
verbascoside: a phenylpropanoid, a disaccharide ester of the hydroxycinnamic acid, caffeic acid, two molecules of which and two sugar molecules (one is rhamnose) being involved; there are numerous variants of this.
vernation: sometimes considered synonymous with ptyxis, although perhaps more accurately describing the folding of leaves in a bud relative to one another, cf. equitant, obvolute, see anaphoric and cataphoric (rotation of leaves in bud).
vernicose: varnished, as if the surface was varnished.
verrucose: covered with wart-like outgrowths, warted; dim. verruculose, with minute wart-like outgrowths, cf. echinate, muricate, prickly. cf. also (of the pollen surface), with wart-like sexine elements, cf. baculate, echinate, fossulate, gemmate, foveolate, pilate, lophate, psilate, reticulate, retipilate, rugulate, scabrate, striate.
versatile: of anthers, swinging freely about the point of attachment to the filament, which is approximately the middle part of the back, i.e. it is really a variant of dorsifixed in which the point of attachment of the filament is narrow; furthermore, such anthers may also be described as being peltate (which they are are almost by definition), and even epipeltate (when the anthers are introrse) and hypopeltate (when the anthers are extrorse), a set of terms which clarifies little: cf. basifixed, centrifixed, embedded.
vesicle: a bladder-like sac or cavity filled with gas or liquid.
vessel: a capillary tube formed from a series of dead cells, the vessel elements, in the xylem, the end walls having broken down all or in part and forming scalariform or simple perforation plates, see tylose, cf. tracheid.
villous: of indumentum, with long, soft hairs, see also Rickett (1954), cf. in particular hirsute, hispid, cf. also arachnoid, arbuscular, canescent, lepidote, puberulous, pubescent, sericeous, stellate, strigose, tomentose, T-shaped, see also glabrescent and glabrate, which refer to stages in the loss of these hairs.
vine: of habit, a climbing or twining plant, usually applied to herbaceous climbers, cf. acaulescent, arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, suffrutescent, schopfbaum, shrub, subshrub, tree, see also life forms.
violoid: a leaf tooth in which the medial vein ends in opaque persistent glanduar termination, no laterals are involved, cf. begonioid, chloranthoid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, spinose, theoid, urticoid.
viscid: of a surface, sticky, coated with a thick, syrupy secretion.
viscidium: in Orchidaceae, a viscid part of the rostellum, itself part of the median stigmatic lobe, clearly defined and removed as part of the pollinarium, serving to attach the pollinaria to an insect or other pollination vector - for other commonly-used terms specific to orchid flowers, see caudicula, column, hamulus, incumbent, labellum, massulae, sectile, stipe, tegula, also epichile, hypochile.
viscin threads/viscin: very fine threads of tapetal origin made up of sporopollenin, attaching to the exine of pollen grains and causing them to clump together when removed by the pollinator; viscin material may take other forms, as in Orchidaceae.
viscous: of a liquid, not pouring freely, having the consistency of syrup or honey.
vittae: oil-containing sacs or tubes, as in the fruits of many Apiaceae, sing. vitta; OR, caulescent species of Vallisneria (Hydrocharitaceae).
viviparous: of seeds, germinating and the seedling becoming apparent before being shed from the parent plant (see Rhizophora, etc.), often also extended to include plants that produce plantlets from vegetative meristems in the inflorescence (= pseudovivipary), cf. cryptovivipary.
Vorläuferspitze: an abaxial outgrowth of the apex of the leaf of a monocot, or sometimes considered to be equivalent to the hyperphyll, a more or less well developed terete or unifacial structure at the tip of the blade, cf. also hypophyll, lamina, leaf base.
waxes: made up of saturated and unsaturated hydrocarbons, also some substitution by oxygen, i.e. fatty acids esterified with long-chain alcohols, see epicuticular wax, cf. gums, mucilages, latex, oils, resins.
weakly crassinucellate: an ovule in which only one layer of cells (not epidermally derived) separates the megasporocyte(s)/embryo sac from the epidermis (Endress 2003c), cf. crassinucellate, incompletely tenuinucellate, nucellar cap, nucellar endothelium, nucellar pad, tenuinucellate (different degrees of development of the nucellus or of the epidermis covering it).
whorl: of leaves or floral organs, a ring of parts borne at the same node along an axis, as distinct from pseudoverticillate, cf. alternate, bijugate, decussate, distichous, opposite, pseudoverticillate,spiral, spiromonistichous, tristichous.
wing: a flattened expansion of a fruit, seed or pollen grain; a thin flange of tissue extended beyond the normal outline of a stem or petiole; relatively large lateral spreading structures, whether petals or sepals, in a papilionoid flower, cf. keel, standard.
xeromorphic: referring to the structural features usually associated with plants of arid habitats (such as hard or succulent leaves), although the plant is not necessarily drought-tolerant, see ericoid leaf, sclerophyll, cf. scleromorphic.
xylem: the vascular tissue that conducts water and mineral salts from the roots to the leaves, see protoxylem, metaxylem, made up variously of xylem parenchyma, rays, fiber tracheids, libriform fibres, and tracheary elements (tracheids, vessels), see also manoxylic and pycnoxylic (basic kinds of wood), and also cf. endarch, exarch, mesarch (pattern of development), cf. phloem.
xyloglucans: a cell wall storage polysaccharide containing both xylose and glucose molecules, forming a matrix that does not have cellulose and pectins in the same proportions as in the primary cell, cf. galactans and mannans.
zooidogamy: the process of fertilisation in which a pollen tube germinates from a distal pollen aperture and the flagellated male gametes are released proximally and swim to the egg apparatus, cf. siphonogamy.
zoöphilous: of flowers pollinated by animals, see cantharophilous, melittophilous , myophilous, psychophilous, sapromyophilous, sphigophilous, (all entomophilous), chiropterophilous, ornithophilous, cf. anemophilous, hydrophilous.