Glossary of Plant Terms

 

R to T

R

raceme: a simple indeterminate inflorescence ending in a non-floral bud and in which the flowers are stalked. cf. spike.

raceme-like: a simple determinate inflorescence ending in a floral bud and in which the flowers are stalked. cf. spike-like.

racemose: like a raceme.

rachilla: the secondary axis of an compound inflorescence or bipinnate leaf.

rachis: rachis; the axis of an inflorescence or of a pinnately compound leaf, or of a pinna in a bipinnate leaf.

rachis extension: the tip of the rachis extending beyond the last leaflet in a paripinnate leaf.

rachis projection: see rachis extension.

rachis spur: see rachis extension.

rachises: plural of rachis.

rainforest: a closed forest dominated by broad-leaved (sometimes narrow-leaved) trees with dense crowns that form a ± continuous layer (canopy) and with one or more specialized growth forms.

ramiflorous: with flowers and fruit produced on woody branches behind the current seasons leaves. cf. cauliflorous.

ray: one of a group of radiating branches or arms, e.g of an umbellate inflorescence or of star hairs (stellate hairs).

ray flower: a small zygomorphic flower with a strap-like or tubular corolla, at the outer edge of the flower head in the family Asteraceae, sometimes called a ray floret.

receptacle: the often more or less expanded top of a pedicel on which a flower arises, or the peduncle expanded or elongated and several flowers arise, as in a capitulum or head; sometimes present as a cup-like structure at the base of a fruit, as in Litsea australis.

recurved: curved backwards (and hence usually downwards), e.g. of the margins of a leaf. cf. revoluteincurved.

regular flowers: see actinomorphic.

reniform: kidney-shaped, broader than long. 

resin: exudate from broken or cut organs that hardens on exposure to air.

resinous: with a hardened sticky surface.

resting bud: buds formed between flushes of new growth, often protected by scale leaves, often called scaly buds. as in Anopterus macleyanus.

resupinate: twisted through 180 degrees, upside down, as in the leaves of Geitonoplesium.

reticulate: forming a network or reticulum; e.g. of veins.

retrorse: pointing or directed away from the apex, e.g. of hairs on a stem. cf. antrorse.

retuse: of an apex, notched with a , often shallow indentation. cf. emarginate and truncate.

reversion shoots: vegetative shoots on the stem and branches which have many of the characteristics of the shoots and leaves on seedlings rather than those on adult shoots.

revolute: rolled backwards (and thus often downwards), e.g. of the margins of a leaf. cf. recurvedincurved.

rhachis: see rachis, which is the preferred spelling.

rhizome: an underground stem, usually growing horizontally. adj. rhizomatous.

rhombic: a 2-dimensional solid, diamond-shaped.

rhomboid: a 3-dimensional shape, diamond-shaped.

riparian: of plants growing by rivers or streams.

root: part of the underground axial system of a plant which does not bear leaves and tends to grow downwards or laterally in the soil. See also adventitious root, aerial root.

rostrate: narrowed into a slender beak or point, beaked.

rounded: obtuse, of an organ, e.g. of the apex of a leaf, or the base of a leaf.

rudimentary: the remains or trace of an organ which has largely disappeared during evolutionary processes. cf. obsoletevestigial.

rufous: reddish.

rugose: wrinkled, covered with coarse lines or furrows.

ruminate: (1) of a surface or tissue, with an irregular, involuted or folded outline, as in a rumen; (2) mottled in appearance. As in the seed of Acmena ingens.

runner: a slender prostrate stem having a bud at the end which sends out leaves and roots.

S

sagittate: shaped like an arrow head, with 2 lobes at the base acute and directed backwards (and often downwards), e.g. of a leaf base.

samara: a dry indehiscent fruit with its wall expanded into a wing.

samara-like: a dry indehiscent winged mericarp that is part of a schizocarp, as in the fruit of Argyrodendron actinophyllum.

sandpapery: scabrous; rough to the touch, with a texture of sandpaper.

saprophyte: an organism deriving its nourishment from dead organic matter and usually lacking chlorophyll. cf. parasite.

sarcotesta: a fleshy seed coat as found in some Cycadaceae (Lepidozamia) and Dysoxylum fraserianum.

scabrous: sandpapery, rough to the touch; having the surface rough with minute hard processes or very short rigid hairs.

scale: a reduced or rudimentary leaf, e.g. covering a dormant bud. See also circular scales, peltate scales.

scale leaf: of a leaf reduced in size and scale-like, axillary buds develop in the axils of scale leaves. 

scaly: (1) of buds, covered in scale leaves which often fall before a flush of new growth, with the new leaves clustered or pseudo-whorled below the scars left on stem after the bud has expanded; (2) of stems, leaves, fruit etc, with surface covered in small circular (peltate) scales or linear (ovate or lanceolate) scales; (3) of a surface covered with overlapping scales (like fish scales), as in the fruit of Calamus muelleri.

scandent: sprawling or climbing, usually applied to young climbing plants where special climbing organs have not yet developed and the habit is shrub-like, a scandent shrub.  As in young plants of Embelia australiana.

scarious: thin, dry and membranous, as in the involucral bracts of Ozothamnus rufescens.

schizocarp: a dry fruit which on dehiscence breaks into 1-carpel indehiscent units or mericarps (cocci). 

schizocarpic capsule: capsule in which individual 1-carpel units or mericarps (segments) dehisce, as in species of Abutilon.

sclereid: a cell with lignified, thick and pitted walls. See stone cells.

scleromorphic: (of leaves) hard and with a large amount of fibrous tissue. cf. mesomorphic.

sclerophyll: a plant with hard, stiff leaves. adj. sclerophyllous.

scrub: a term for rainforest, predominantly used in Queensland or northern New South Wales, as in Mangrove Scrub, Goodnight Scrub and Murray Scrub. 

scurfy: covered with small bran-like scales.

secondary veins: lateral veins; veins arising from the midvein.

seed: the reproductive body formed from a fertilized ovule, and comprising an embryo and a surrounding protective seed coat or testa.

segment: a free or almost free part of an organ.

semi-circular: half a circle.

sepal: one of the outer leaf-like structures surrounding the petals and fertile organs of the flower, usually green; collectively called the calyx.

sepaloid: resembling a sepal.

septum: a partition or cross-wall; pl. septa.

sericeous: see silky.

series: several similar structures in rows, usually close together, as in filament-like processes in the corona of Passiflora foetida.

sessile: flowers without a pedicel, as in a spike or a head inflorescence, leaves without a petiole, or leaflets without a petiolule.

seta: bristle or stiff hair. pl. setae.

setaceous: bristle-like, narrow and stiff.

sheathing: stem clasping; tubular and enclosing another structure, usually clasping or surrounding the stem, as of a stem-clasping petiole, of stipules, as in Ficus macrophylla.

short-acuminate: of a leaf apex, tapering abruptly to a short point. cf. long-acuminate.

shrub: a much-branched woody plant and usually with many stems from near ground level. Tall shrubs are mostly 3–6 m high; small shrubs less than 3 m high; prostrate shrubs shrubs less than 1 m high with trailing branches that often rooted at the nodes; subshrubs less than 0.5 m high and with stems herbaceous.

sigmoid: curved twice in opposite directions, as in the flowers of Pararistolochia laheyana.

silky: sericeous; covered with fine soft ± straight appressed hairs aligned in the same direction, with a lustrous sheen and satin-like to the touch.

simple:of a leaf, with lamina not divided into leaflets; of an inflorescence that is unbranched; of a fruit that is derived from a single ovary without any accessory layers surrounding it. cf. unifoliolate, compound. ‘Simple’ leaves in the key includes simple leaves, 1-foliolate (unifoliolate) leaves, scale leaves and phyllodes; of hairs, that are undivided.

sinuate: with a deeply wavy margin, with a number of regular curved indentations or small lobes. cf. undulate.

sinus: a gap or recess between two lobes, segments or teeth.

solitary: borne singly, e.g. of flowers not grouped into an inflorescence.

sorus: a discrete aggregate of sporangia in ferns. pl. sori.

spadix: a spike-like inflorescence with an enlarged and elongated fleshy axis and with the flowers and fruit embedded in it, as in Pothos.

spathe: a large bract enclosing a flower cluster, as in many palms, e.g. Archontophoenix cunninghamiana.

spathulate: spoon-shaped, e.g. of a leaf which is broad and rounded at the apex and narrowed towards the base.

species: taxon comprising individuals, or populations of individuals, that show certain common features and are capable of interbreeding to produce fertile offspring. cf. genus.

spicate: in the form of a spike.

spike: a simple inflorescence, terminating in a non-floral bud, in which the flowers are sessile. cf. raceme.

spike-like: a simple inflorescence, terminating in a floral bud, in which the flowers are sessile. cf. raceme-like.

spine: a stiff process with a sharp point, formed by a modification of a plant organ that contains vascular tissue, e.g. a lateral branch or a stipule. adj. spinose. cf. prickle.

spinescent: spine-like, ending in a spine; modified into a spine.

spinose: spiny, having spines.

spiral: alternate; of leaves borne singly at different levels on the axis, but not in a single vertical line; leaves borne spirally are said to be alternate on the stem. cf. whorledalternate.

spongy: having the texture of a sponge.

sporangium: a structure in which spores are formed. pl. sporangia.

spore: a unicellular or few-celled asexual or sexual reproductive unit, not containing an embryo.

sporophyll: a specialized leaf-like organ on which one or more sporangia are borne.

stamen: one of the male organs of the flower, consisting of a pollen-bearing anther and a filament or stalk.

staminode: a rudimentary or modified stamen, often resembling a stamen to some degree but not producing viable pollen grains. Found in female flowers or bisexual flowers that are functionally male flowers or as an extra whorl in male flowers.  As in species of Commersonia and Eupomatia.

standard: the large upper petal of a pea flower, in family Fabaceae, subfamily Faboideae, as in Derris involuta.

star hair: see stellate hair.

stellate hair: star hairs; a hair with several rays, branches or arms, the rays spreading and star-like.

stem: the main axis or a branch of the main axial system of a plant and typically bearing leaves and generally above the ground.

sterile: without reproductive structures, not producing viable seed, spores or pollen. cf. fertile.

stigma: the structure on the gynoecium upon which pollen is deposited and from where it can germinate and fertilize the ovules. Usually found at the top of the style or the apex of the ovary if the style is not developed.

stilt roots: prop roots; roots growing down to the soil from the lower stem or branches, as in some mangroves and palms, e.g. Archontophoenix cunninghamiana.

stinging hair: a hollow hair seated on a gland which secretes an irritating fluid, e.g. as in species of Dendrocnide.

stipe: a small stalk; in ferns the petiole of a frond.

stipels:= small stipule-like organs found on compound leaves, usually paired at the base of the petiolules of leaflets. sing. stipel.

stipellae: see stipels.

stipitate: stalked.

stipulate: possessing stipules.

stipule scar: the scar left by a stipule after it has fallen.

stipules: one, several or a pair of appendages sometimes developed on the stem at the base of a petiole; can be leafy, scariousspinose or modified into tendrils. Stipules frequently fall off early and the only indication of stipules is the presence of scars on the older stems.

stolon: a more or less horizontal stem growing above ground and rooting at the nodes. adj. stoloniferous.

stomate: a pore bounded by two guard cells in the epidermis, especially in leaves, through which gases diffuse.

stone: the inner woody, cartilaginous or papery layer (endocarp) surrounding the seed(s) in a drupe, as in Gmelina leichhardtii and Elaeocarpus grandis. See quandong.

stone cell: short sclereid cell responsible for the distinctive hardness of texture of some tissues, e.g. in the fruit of pears.

strobilus: (in conifers and cycads) a spore-bearing spike covered in overlapping sporophylls (reduced spore-bearing leaves), a ‘cone’. pl. strobili.

strophiole: a small aril-like structure on the testa (seed coat) near the hilum. adj strophiolate. cf. arilcaruncle.

style: the narrowed portion of the gynoecium, usually attached at the apex of the ovary and usually ending in the stigma.

style head: the expanded structure at the apex of the 2 fused styles, thickened, and usually with stigmas borne below head, as in Hoya australis.

sub-: a prefix, below or under.

sub-opposite: nearly opposite but not regularly so, as in the arrangement of leaves. cf. opposite, alternate, whorledpseudo-whorled

subshrub: a plant that is shrubby and often sparsely branched, stems ± herbaceous and usually arising from a woody rootstock, often less than 1 m high.

subspecies: a taxonomic category below species, differing in minor morphological characters such as size or shape of parts, and either partially or completely isolated, usually by means of geographical or ecological barriers.

subtending: describing a leaf whose axil gives rise to a bud (the axillary bud) which may develop into a branch or inflorescence.

subtropical rainforest: STRf occurs in warm fertile sites with high rainfall.

subulate: awl-shaped, narrow and tapering to a point but thick enough in cross section to make it stiff and hard.

succulent: juicy, fleshy.

sucker: a vegetative shoot of underground origin.

superficial: on the surface, e.g. of sori on a fern frond.

superfluous: (in nomenclature) a name for a taxon for which an earlier legitimate name already exists.

superior berry: berry developed from a superior ovary.

superior ovary: an ovary with the floral parts (petals, sepals and stamens) inserted below it and the ovary wall not fused to the receptacle. cf. inferior ovary, half-inferior ovary.

supra-axillary: above the axil of a leaf, as in inflorescences, as in Glochidion sumatranum and with axillary buds above the axil, as in Sarcopetalum harveyanum.

suture: line of splitting in a dry dehiscent fruit, as in a capsulepodfollicle etc. 

swamp rainforest: Swamp Rf or palm Rf grows on poorly drained sites in coastal lowlands and is usually dominated by palms. 

syconium: a ‘fig’, the multiple fruit formed in figs (e.gFicus watkinsiana) by the invagination of the floral axis where the minute flowers and fruit are inside the swollen inflorescence stem. cf. aggregate fruit, syncarpium.

symmetric: divisible into two or more equal parts, as in symmetry of flowers. cf. asymmetric.

syncarpium: a multiple fruit consisting of several united fruit, originating from more than one flower, usually fleshy, as in Maclura cochinchinensis and Gynochthodes jasminoides. cf. aggregate fruitsyconium.

syncarpous: an ovary formed from two or more united carpels. cf. apocarpous.

synonym: a surplus scientific name where 2 or more names are applied to the same taxon.

T

taxa: plural of taxon.

taxon: a term used to describe a member of any taxonomic category, e.g. genusspeciessubspeciesvariety.

tendril: a long slender, coiled organ derived from an axis or leaf or other organ, assists the plant in climbing.

tepal: a segment of a perianth that is not differentiated into a sepal or petal.

terete: a 3-dimensional shape, cylindrical and elongated, circular in cross section.

terminal petiolule: the stalk of the terminal leaflet of a pinnately 3-foliolate leaf or an imparipinnate leaf; the stalk is usually jointed at the point where the rachis extension beyond the last leaflet meets the true petiolule of the leaflet.

ternate: in threes, for a leaf with 3 leaflets the preferred term is a 3-foliolate leaf. cf. biternate, triternate.

tessellated: with colours or shapes arranged in squares to give a chequered appearance, e.g. of bark, as in Pleiogynium timorense.

testa: the seed coat.

tetramerous: 4-merous; of a flower, having the floral parts, especially the sepals and petals or tepals, and usually the stamens, in whorls of 4 or multiples of 4. Many members of the families Proteaceae and Rutaceae are 4-merous, e.g .Acronychia oblongifolia.

thorn: see spine, sometimes used for a reduced lateral branch with a sharp point. cf. prickle.

three-veined: 3-veined, a leaf with 3 main veins arising from near the base, and extending to more than half way up the leaf.

throat: of a corolla tube or hypanthium, the top where the tube joins the lobes, as in Pandorea floribunda and Aristolochia elegans.

thyrse: a compound inflorescence ending in a non-flower (vegetative) bud and with mixed types of branching, the main axis bearing several or many lateral cymes.

thyrsoid: a compound inflorescence ending in a flower bud and in which the main axis is raceme-like and the lateral ones cymose, i.e. similar to a thyrse except for the terminal flower.

tomentose: covered with dense intertwined hairs. cf. woolly.

tomentum: a dense covering of intertwined hairs, e.g. of simple hairs.

toothed: of margins, regularly or irregularly incised.

tortuous: twisted and bent in different directions.

tree: a woody plant usually with a single distinct trunk and generally more than 3 m high.

triad: a group of three, as in the ultimate units of some mistletoe inflorescences.

triangular: a 2-dimensional shape, 3-angled and 3-sided, and attached at the broader end.

trichome: a collective term to describe epidermal outgrowths, without vascular tissue, e.g. hairs, bristles, scales, prickles, etc.

trifid: divided into three, as in a stigma. 

trifoliate: 3-foliate; having three leaves. cf. trifoliolate.

trifoliolate: 3-foliolate; of a leaf, having three leaflets. See also palmately trifoliolate, pinnately trifoliolate.

trigonous: 3-angled in cross section and obtusely-angled, as in branchlets of Callitris glaucophylla. cf. triquetrous.

trimerous: 3-merous; of a flower, having the floral parts, especially the sepals and petals or tepals, and usually the stamens, in whorls of 3 or multiples of 3. As in most monocotyledons, e.g. Eustephus latifolius.

trimorphic: with 3 different forms, as in leaves of Wollemia nobilis and the fern Teratophyllum brightiae.

tripinnate: 3-pinnate; a compound leaf with lamina pinnately divided three times. cf. bipinnate.

triquetrous: 3-angled in cross section and acutely-angled. cf. trigonous.

triternate: 3-ternate; three times ternate, the 3 pinnae each divided twice into 9 pinnules. cf. ternatebiternate.

truncate: ending abruptly as though cut off, e.g. of a apex. cf. emarginateretuse.

T-shaped hairs: 2-branched hairs; hairs with 2 branches at the apex of a basal stalk, the length of the arms usually of a similar length, shaped like the letter T, or sometimes the branches are unequal and referred to as 2-branched hairs, as in Cephalaralia.

tuber: an underground storage organ formed by the swelling stem, e.g. a potato. adj. tuberous.

tuberculate: warty; covered in knobbly or wart-like projections, as in Zieria tuberculata.

tubercules: small wart-like outgrowths.

tubular flower: a small flower in which the corolla is tubular and 3- to 5-toothed, as in disc flowers and filiform flowers in family Asteraceae.

turbinate: top-shaped.

turgid: swollen.

two-branched: 2-branched; of hairs with 2 branches, the branches of equal length, or unequal length as in Cephalaralia. cf. T-shaped hairs.

two-ranked: 2-ranked; arranged in two vertical rows on opposite sides of a stem and in the same plane.

type: a designated herbarium specimen on which a species name is based.

type form: if there is variation within a species, the form that is represented in the type specimen is considered to be the type formas in Notelaea longifolia forma longifolia.

type subspecies: if there is variation within a species, the subspecies that is represented in the type specimen is considered to be the type subspecies, as in Abrus precatorius subsp. precatorius.

type variety: if there is variation within a species, the variety that is represented in the type specimen is considered to be the type variety, as in Clerodendrum longiflorum var. longiflorum.

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