Glossary of Plant Terms

 

I to M

I

imparipinnate: odd-pinnate or unevenly pinnate, a pinnate leaf with a single terminal leaflet, usually with an odd number of leaflets. cf. paripinnate.

impressed: sunken, in relation to the rest of the surface, e.g. veins on the upper surface of a bullate leaf.

incised: cut deeply and sharply, as in a leaf margin.

included: enclosed, not protruding, e.g. of valves which do not extend beyond the rim of a capsular fruit. cf. exserted.

incurved: of leaf margins, curved inwards or upwards. cf. recurved.

indefinite: variable in number; numerous, e.g. of stamens; of  growth of a shoot, continuous.

indehiscent: not opening at maturity to release seed or pollen; e.g. indehiscent fruit. cf. dehiscent.

indeterminate: of growth or branching pattern, where a vegetative bud persists and produces successive lateral branches; of an inflorescence or part of an inflorescence which does not end in a flower or an aborted flower bud, as in thyrseraceme or spike. cf. determinate.

indigenous: occurring naturally in the area; not introduced. cf. endemic.

indumentum: a general term for the hairy or scaly covering of plants. 

indusium: the flap of tissue or hairs covering the sorus of a fern.

inferior berry: berry formed from an inferior ovary, as in Diplocyclos and Opuntia.

inferior ovary: an ovary with the floral parts (petals, sepals and stamens) inserted above it and the ovary fused to the receptacle. cf. superior ovary, half-inferior ovary.

inflated: swollen, bladder-like, as in some fruit, e.g. Harpullia alata.

inflorescence: a general term for the flower-bearing system of a plant, and more particularly for portions of such systems separated from one another by vegetative portions of the plant. cf. infructescence.

infraspecific: of taxa within a species, e.g. subspeciesvariety or forma.

infructescence: a general term for the fruit-bearing system of a plant. cf. inflorescence.

inter-: a prefix, between.

interjugary glands: of glands, present along the rachises of compound leaves between the pairs of leaflets or pinnae, as in some Acacia species. cf. jugary glands.

intermediate leaves: leaves that develop after the juvenile leaves and before the mature leaves, as in Streblus pendulinus.

internode: portion of the stem between two successive nodes. cf. node.

interpetiolar: between the petiole bases of a pair of opposite leaves.

interpetiolar stipule scars: scars between the petiole bases, remaining after the falling of the interpetiolar stipules. 

interpetiolar stipules: stipules between the petiole bases of a pair of opposite leaves.

intra-: a prefix, inside.

intramarginal: situated inside the margin but close to it, e.g. intramarginal veins.

intramarginal vein: a vein of constant thickness that extends from the base to the apex of the lamina just inside the margin. It should not be confused with looping lateral veins. There should not be any major bends although slight indentations may occur at the junction with the main lateral veins. 

intrapetiolar stipule: a single stipule that is attached to the stem between the petiole and the stem, i.e. inside the petiole, as in Erythroxylum and Schefflera.

intrapetiolar stipule scar: a scar encircling the stem above the petiole base, remaining after the falling of the intrapetiolar stipule.

intricate: of plants, with many stiff entangled branches, as in Everistia vacciniifolia.

introduced: not native to the area; not indigenous.

introrse: opening inwards, usually used to describe anthers dehiscing inwards.

invaginated: a pocket formed by the process of turning in on itself, as in the floral receptacle of figs (Ficus species where the minute flowers and individual fruit are inside the swollen inflorescence receptacle, the ‘fig’). 

involucral bracts: the bracts surrounding the capitulum and forming the involucre, as in many species of Asteraceae.

involucre: (1) a whorl or several whorls of bracts surrounding a flower or an inflorescence (as around a head in many species of Asteraceae); (2) = indusium, as covering the sori, as in Arthropteris beckleri.

involute: rolled inwards, of a leaf margin or petiole.

irregular flowers: see zygomorphic.

isobilateral: an organ, such as a leaf, with the upper and lower surfaces similar, in colour and structure.

J

joint: (1) an articulation, as in a 1-foliolate leaf; (2) a segment of some cladodes, as in many Cactaceae; (3) a node.

jugary glands: of glands present along the rachis of compound leaves near or between the bases of opposite leaflets or pinnae, as in some Acacia species. cf. interjugary glands.

jugate: paired.

juvenile leaves: the first-formed leaves, especially when they differ from the adult leaves, as in Parsonsia straminea and Eidothea hardeniana.

K

keel: (1) a ridge like the keel of a boat, usually on the back of an organ; (2) the two lower, united petals of a pea flower, as in family Fabaceae (subfamily Faboideae), as in Derris involuta.

kernel: the softer, usually edible part contained within the ‘shell’ of a nut or drupe.

L

labellum: the distinctive central petal in orchids, usually differing in size and shape from those on either sideas in Pseudovanilla foliata.

lacerate: as if torn; irregularly cut or torn.

laciniate: applied to margins as if cut into numerous narrow teeth or lobes, e.g. leaves, stigmas, tepals, arils, etc.

lamina: an expanded portion of a leaf or leaflet, or of petals. pl. laminas.

lanceolate: a 2-dimensional shape, lance-shaped; broadest below the middle and tapering to the apex and 3–6 times as long as wide.

lateral primary veins: basal pair of lateral veins that extend up the lamina so that it appear 3-veined from, or near the base, more prominent than other lateral veins, as in species of Rhodamnia.

lateral veins: secondary veins, arising from the midvein, as in leaves and leaflets.

latex: a fluid exuded from cut surfaces of petioles and stems of some plants, usually milky, sometimes yellowish and watery, e.g. as in many Moraceae and Apocynaceae and some Euphorbiaceae.

leading shoot: primary shoot in climbing plants seeking support on which to climb, sometimes with reduced leaves, as in Ripogonum elseyanum and Cryptostegia grandiflora.

leaf: an organ borne on the stem of a plant, usually expanded and green; in a simple and 1-foliolate leaf; typically consisting of the more or less expanded lamina and the petiole, and in compound leaves with lamina divided into a number of leaflets. pl. leaves.

leaflet: one of the ultimate segments of a compound leaf. cf. pinnapinnule.

leaf-opposed: arising from the stem opposite a petiole, as for some tendrils, and some inflorescences.

legume: (1) a pod, a dry dehiscent fruit formed from one carpel and having two longitudinal lines of dehiscence; rarely as in Derris involuta the pods are indehiscent; (2) a member of the family Fabaceae.

lenticel: a small raised corky spot or line appearing on young bark, through which gaseous exchange occurs.

lepidote: covered with small, membranous scales.

liana: liane; a woody climbing plant.

life form: see growth form.

lignified: converted into wood, hardened.

lignotuber: a woody swelling, partly or wholly underground, at the base of certain plants and containing numerous buds, as in many eucalypts.

ligulate: with a ligule, strap-shaped.

ligule: a strap-shaped structure, the corolla of ray flowers in family Asteraceae with a strap-shaped limb.

limb: (1) the upper, usually expanded, flat part of the calyx or corolla (especially if united in a tube below); (2) a large branch.

linear: long and narrow with more or less parallel sides, more than 12 times as long as broad.

linear scale: elongated scales, as on the fronds of some palms, or on the rhizomes and stipes of many ferns.

linear-lanceolate: more than 12 times as long as broad and broadest in the lowest third and tapering to the apex.

linear-oblanceolate: more than 12 times as long as broad and broadest in the upper third and tapering to the base.

lithophyte: a plant growing on rocks, e.g. some ferns. cf. epiphyte.

littoral: on or growing near the seashore.

littoral rainforest: LRf, rainforest growing near the sea.

lobe: part of a leaf or fruit (or other organ) formed by incisions on the margins or surface towards the midrib or centre; organ considered to be shallowly lobed if incised to less than halfway or deeply lobed if incised to more than halfway.  Also see palmatifidpalmatisectpinnatifid and pinnatisect.

lobed: of an organ (leaffruit etc) divided into lobes.

loculus: locule; a more or less closed cavity, as in a carpel or an ovary where the ovules develop, or in a fruit where the seeds are borne, or a compartment in an anther where the pollen is formed.  pl. loculi (locules), adj. locular.

lomentum: pod (legume) that breaks transversely into 1-seeded indehiscent articles or segments when mature, as in Desmodium acanthocladum.

long-acuminate: describing a leaf apex narrowed and gradually tapering to a long point. cf. drip tip, short-acuminate.

longitudinal venation: usually with several veins (can be as few as 2 or 3) extending from the base to the apex of the lamina, the veins may be parallel or not parallel with each other, the lamina can be variable in shape. cf. parallel venation.

longitudinally veined: a lamina with longitudinal venation.

M

malesia: island group west and north of New Guinea towards Asia, including East Timor, Indonesia (excluding Irian Jayva), Borneo and the Philippines.

mangrove: a shrub or small tree growing in salt or brackish water and often with pneumatophores or aerial roots.

marginal: at or very close to the margin, e.g. of glands. cf. intramarginal.

mealy: covered with coarse flour-like powder.

medifixed: attached at the middle. Usually used to describe two-armed hairs attached at or near the middle. cf. basifixed, T-shaped hairs, 2-branched hairs.

melanesia: island group extending north and east and south-east of New Guinea, including Bismarck Archipelago, Solomon Islands, Vanuatu, New Caledonia and Fiji. Abutting to the north and east with the Pacific Islands group.

membranous: thin and flexible, semi-translucent, as in the ocrea of Acetosa sagittatacf. chartaceous.

mericarp: one segment of a fruit that breaks at maturity into 1-carpel units and each segment dehisces separately, as in a schizocarp, or schizocarpic capsule.

merous: a suffix indicating the number (or multiple of that number) of parts in each floral whorl, e.g. a 5-merous flower is one with the number of sepals, petals and stamens 5, or divisible by 5.

mesocarp: the middle layer of the pericarp, e.g. the succulent part of a fleshy fruit between the skin (exocarp) and the endocarp, or the seed when the endocarp is not developed.

mesomorphic: (of leaves) soft and with little fibrous tissue, but not succulent. cf. scleromorphic.

micropyle: a small opening through the integument(s) of an ovule, persisting as a pore in the testa (seed coat).

microspecies: segregate species of a larger species or species-aggregate, e.g. Rubus anglocandicans.

midrib: the support structure of the lamina of a simple leaf or leaflet, a continuation of the petiole, running the full length of the leaf or leaflet, often prominently raised or depressed.

midvein: the primary vein is the main vascular supply system of the lamina of a leaf, leaflet, petal etc, and runs from the base to the apex and is usually the most prominent vein, from which arise the lateral or secondary veins. 

minute: very small, usually less than 1 mm long.

mixed forest: occurs in all subforms of rainforest where large eucalypts or other trees such as Brush Box (Lophostemon confertus) are present as emergents forming an additional upper layer above the rainforest canopy.

moniliform: constricted between seeds longitudinally, like a string of beads, as in some Acacia pods.

monochasium: cyme in which the branches arise singly. cf. dichasium.

monocotyledons: a major group of angiosperms (flowering plants), characterized by the embryo usually having one cotyledon (seed leaf). cf. dicotyledons.

monoecious: having male and female flowers on the same plant. cf. dioecious.

monotypic: of a genus, having only one species, as in Akania bidwillii. cf. unigeneric.

mucilage:a gelatinous secretion.

mucro: (of an apex) blunt in outline but with an abruptly narrowed apical point which may be sharp or blunt.

mucronate: having a mucro

multiple fruit: a cluster of fruits produced from more than one flower and appearing as a single fruit, often on a swollen axis, as in family Moraceae. e.g. syncarpiumsyconium. cf. aggregate fruit.

multistemmed: describing a plant, often a shrub, with a number of stems rising from ground level.

mycorrhiza: a symbiotic association between a fungus in or on the roots.

myrmecophilous: Plants with an affinity for ants, such as hollow stems in which ants nest.

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