sac: a pouch or cavity; see pollen-sac, embryo-sac.
sagittate: shaped like an arrow-head.
salverform: of a sympetalous corolla, salver-shaped, i.e. with a slender tube and abruptly expanded flat, rotate limb (like the corolla of Primula).
samara: a dry, indehiscent fruit with its wall expanded into a wing.
saprophyte: an organism deriving its nourishment from dead organic matter and usually lacking chlorophyll. cf. autotrophic, epiphyte, parasite.
scaberulous: slightly or minutely rough to the touch, minutely scabrous.
scabridulous: slightly rough; diminutive of scabrous.
scabrous (= scabrid): rough to the touch.
scalariform: having a ladder-like pattern.
scale: a reduced or rudimentary leaf, e.g. surrounding a dormant bud; a thin flap of tissue of epidermal origin, e.g. at the base of a stamen in Simaroubaceae; a thin scarious trichome which is flattened and variously shaped.
scape: the stem-like, flowering stalk of a plant with radical or rosulate leaves.
scarious: dry and membranous.
schizocarp: a dry fruit formed from more than one carpel but breaking apart into 1-carpel units when ripe. cf. mericarp.
sclerenchyma: mechanical tissue with heavily thickened cell walls.
sclereid: a cell (usually elongated) with a strongly lignified wall.
scleromorph: a plant whose leaves (or stems, if leafless) are hard in texture, usually having thick cuticle and containing many fibres. cf. xeromorph.
sclerophyllous: with leaves stiffened by sclerenchyma.
scorpioid: of a cymose inflorescence, branching alternately on one side and then the other, with the main axis coiled like the tail of a scorpion. cf. helicoid.
scribble: irregular lines on the bark of some eucalypts, being the old tunnels burrowed by moth larvae between bark layers and exposed when the outer layer falls.
secund: with all the parts grouped on one side or turned to one side (applied especially to the grouping of flowers in an inflorescence or stamens in a flower).
seed: a propagating organ formed in the sexual reproductive cycle of gymnosperms and angiosperms, consisting of a protective coat enclosing an embryo and food reserves.
segment: a part or sub-division of a divided organ; one of a group of similar organs named collectively, e.g. one petal = a segment of a corolla.
semicraspedodromous: pinnate venation 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. acrodromous, brochidodromous, eucamptodromous.
sepal: a member of the (usually green) outer whorl of non-fertile parts surrounding the fertile organs of a flower.
sepaloid: looking like sepals, e.g. of bracts, usually green and arranged in a ring beneath a flower.
septate: divided internally by partitions.
septicidal: of the dehiscence of a fruit, along lines coinciding with the partitions between loculi. cf. loculicidal.
septifragal: of the dehiscence of a fruit, the valves or backs of the carpels breaking away leaving the septa intact.
septum: a partition. pl. septa.
seriate: in rows or whorls.
sericeous: silky; covered with silky hairs.
serrate: toothed, with asymmetrical teeth pointing forward.
serrulate: finely serrate.
sessile: without a stalk, e.g. when applied to a stigma, indicates that the style is absent, the stigma being 'sessile' on the ovary.
seta: a bristle or stiff hair; terminal seta: an appendage to the tip of an organ, e.g. to the primary rachis of a bipinnate leaf in Acacia. adj. setaceous.
setiferous: bearing setae.
setose: covered with bristles.
setulose: covered with fine bristles; resembling a fine bristle.
sheath: the lower portion of a grass leaf, clasping the stem; one of the wing-like extensions to the margins of the petiole which wrap around and enclose the stem; closed sheath: one in which the wings are fused to form a cylinder; open sheath: one with a slit on the side opposite to the lamina.
shrub: a woody plant less than 5 metres high, either without a distinct main axis, or with branches persisting on the main axis almost to its base.
sigmoid: doubly curved in opposite directions like the letter S.
siliceous: containing silica.
silicula: a short siliqua, not more than twice as long as its width.
siliqua: a dry, dehiscent fruit formed from a superior ovary of two carpels, with two parietal placentas and divided into two loculi by a false septum between the placentas.
simple: undivided; of a leaf, not divided into leaflets; of a hair or an inflorescence, not branched.
sinistrorse: turned towards the left. cf. dextrorse.
sinuate: with deep, wave-like depressions along the margin. cf. undulate.
sinus: a notch or depression in the margin of an organ.
solitary: of flowers, borne singly, not grouped in an inflorescence.
sorus: in ferns, a discrete group of sporangia. pl. sori.
spadix: a spicate inflorescence with a stout, often succulent axis.
spathaceous: like a spathe; with a spathe.
spathe: a large bract ensheathing an inflorescence.
spathella: in some Podostemaceae, a 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.
spike: an unbranched, indeterminate inflorescence in which the flowers are without stalks. adj. spicate.
spikelet: a unit of the inflorescence in grasses, sedges and some other monocotyledons, consisting of one to many flowers and associated glumes.
spine: a stiff, sharp-pointed structure, formed by modification of a plant organ, e.g. a lateral branch or a stipule.
spinescent: ending in a spine; modified to form a spine.
spinose: bearing spines.
spiral: of leaves or floral organs, borne at different levels on the axis, in an ascending spiral. cf. cyclic, whorl.
sporangiate: bearing spores (or pollen).
sporangiophore: the stalk of a sporangium; in Botrychium, the branched axis bearing sporangia.
sporangium: a structure within which spores are formed. pl. sporangia.
spore: a simple propagule, produced either sexually or asexually, and consisting of one or a few cells.
sporocarp: a fruiting body containing sporangia.
sporogenous: of cells or tissues, spore-generating.
sporophyll: a specialised leaf-like organ on which one or more sporangia are borne.
sporophyte: a plant, or phase of a life cycle, that bears the spores formed during the sexual reproductive cycle.
spur: a tubular pouch at the base of a perianth part, often containing nectar.
stamen: one of the male organs of a flower, consisting typically of a stalk (filament) and a pollen-bearing portion (anther). adj. staminate.
staminal corona: in Asclepiadaceae, fleshy outgrowths of tissue, attached dorsally to the staminal column at the base of the filaments or on the backs of the anthers. See gynostegial corona.
staminode: a sterile stamen, often rudimentary, sometimes modified, e.g. petaloid.
staminophore: a band of tissue around the apex of the hypanthium in a eucalypt flower, on which the stamens are inserted.
standard (= vexillum): the posterior petal in the flower in Fabaceae and Caesalpiniaceae.
stellate: star-shaped; consisting of star-shaped cells.
stem: the main axis or a branch of the main axial system of a plant, developed from the plumule of the embryo and typically bearing leaves.
stigma: the pollen-receptive surface of a carpel or group of fused carpels, usually sticky.
stipe: a small stalk; in ferns, the petiole of a frond.
stipel: stipule-like appendage at the base of a leaflet (in unifoliolate leaves, inserted on the petiole, not on the stem). pl. stipellae. adj. stipellate.
stipitate: stalked; borne on a stipe; of an ovary, borne on a gynophore.
stipule: one of a pair of appendages at the bases of leaves in many dicotyledons.
stolon: a prostrate or trailing stem that produces roots at the nodes. cf. rhizome, runner.
stoloniferous: having stolons; trailing over the soil surface and rooting at the nodes.
stoma: a pore; a pore in the epidermis of a leaf or other aerial organ, providing for gaseous exchange between the tissues and the atmosphere. pl. stomata.
stomium: a region of dehiscence, e.g. of an anther in flowering plants. pl. stomia.
stone cell: a ±isodiametric sclereid.
stramineous: straw coloured.
striate: striped with parallel longitudinal lines or ridges.
strigose: with sharp, stiff hairs which are appressed to the surface.
strigulose: minutely strigose.
strobilus: a 'cone' consisting of sporophylls borne close together on an axis.
strophiole: see caruncle.
struma: a cushion-like swelling, e.g. at the apex of staminal filaments in Dianella.
style: an elongated part of a carpel, or group of fused carpels, between the ovary and the stigma.
stylopodium: a disc-like enlargement of the base of the style.
subulate: narrow and tapering gradually to a fine point.
sulcate: grooved; furrowed.
superior: of an ovary, borne above the level of attachment of the other floral parts, or above the base of a cup (hypanthium) that is free from the ovary and bears the perianth segments and stamens. cf. inferior.
suture: a line of junction between two fused organs; a line of dehiscence.
syconium: a multiple fruit with a hollow centre, e.g. in figs (Ficus).
sympatric: of distributions of two taxa or populations, having coincident or overlapping ranges of distribution. cf. allopatric, parapatric.
sympetalous: (= gamopetalous): with the petals united by their margins, at least at the base. cf. polypetalous.
sympodial: of growth, without a single, persistent growing point; changing direction by frequent replacement of the growing apex by a lateral growing point below it; of a stem, growing in the above manner. cf. monopodial.
synandrium: an androecium with the anthers of the stamens cohering. cf. syngenesious.
synangium: a group of fruits fused into a single structure; in ferns, a group of fused sporangia.
synapomorphic: of a character, derived, and shared by two or more taxa. cf. apomorphic, autapomorphic.
syncarp: a structure consisting of several united fruits, usually fleshy. cf. aggregate fruit.
syncarpous: of a flower, having two or more carpels, all fused together.
syngenesious: of the stamens of one flower, fused together by the anthers, e.g. in Asteraceae. cf. monadelphous, synandrium.
syntepalum: in some Musaceae, a unilaterally split tube formed by the coherence of 3 sepals and 2 petals.
syntype: one of two or more specimens cited by the author at the time of publication of a name if no holotype was designated; any one of two or more specimens simultaneously designated as types; isosyntype: a duplicate of the syntype. cf. type.
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Last updated on 13 May 1999.