habit: the general appearance of a plant, including size, shape and growth form. Fig. 1.
habitat: the kind of place in which a plant grows.
hair: an outgrowth of the epidermis, usually elongate and consisting of one or more cells. Fig. 14 & Fig. 15.
half-inferior: of an ovary, partly below and partly above the level of attachment of the perianth and stamens. Fig. 12 C.
halophyte: a plant adapted to living in a highly saline area; a plant that accumulates a high concentration of salt in its tissues.
hamulus: on column of orchid, thread of tissue between pollen-mass and viscid disk on upper part of stigma (rostellum).
haploid: having a single set of chromosomes in the nucleus. cf. diploid, polyploid.
hastate: spear-shaped; of a leaf, with a narrow, pointed lamina with two basal lobes spreading more or less at right angles to the petiole. Fig. 7 I.
haustorium: the absorbing organ of some parasitic or hemiparasitic plants through which substances pass from the host to the parasite.
head (capitulum): a dense cluster of more or less sessile flowers, e.g. in Asteraceae a group of florets sessile on a common receptacle. Fig. 17 O & P.
heath: (1) a plant community dominated by small, closely spaced shrubs, most of which have stiff and often small leaves; (2) a plant with small hard leaves, as in many Ericaceae subfamily Styphelioideae.
hemi-: prefix: half.
hemiantropous: see hemitropous.
hemiparasite: an organism that is partly parasitic on another organism, e.g. mistletoes.
hemitropous: of an ovule with the body at right angles to the funicle, with the funicle attached near the middle and the micropyle terminal; embryo sac straight. Fig. 21 C. cf. anatropous, amphitropous, campylotropous, orthotropous.
herb: a plant that does not produce a woody stem, although it may be woody at the base. adj. herbaceous. cf. forb.
herbaceous: herb-like, not woody; often applied to bracts, bracteoles or floral parts that are green and soft in texture.
hermaphrodite: of a plant with all flowers bisexual.
hesperidium: fleshy indehiscent fruit derived from a single gynoecium, with an outer leathery rind and septate interior (e.g. Citrus).
heterogamous: producing flowers of 2 or more kinds with respect to their fertile organs, i.e. combination of male, female or bisexual. cf. homogamous.
heterogeneous: consisting of dissimilar parts.
heteromorphic: of two or more forms.
heterosporous: a plant producing spores of two different kinds in the sexual reproductive cycle. See megaspore, microspore. cf. homosporous.
heterostylous: flowers with styles of different lengths, sizes or shapes in the same species. cf. homostylous.
hilum: the scar on the seed coat where the seed was attached to the funicle.
hip: the false aggregate ‘fruit’ in Rosa species. Fig. 18 V.
hirsute: bearing coarse, moderately stiff, longish hairs. Fig. 14 L.
hispid: bristly. See bristle.
hispidulous: minutely bristly.
hoary: with a dense covering of hairs so that the surface appears whitish or greyish.
holotype: a single specimen chosen by the author of a plant (or animal) name, at the time of original publication, as that to which the name shall apply; the ‘voucher specimen’ of a name. cf. lectotype which is chosen by a later author.
homosporous: producing only one kind of spore in the sexual reproductive cycle, and hence each with gametophyte producing both male and female gametes. cf. heterosporous.
homostylous: flowers with styles of similar length, size and shape in the same species. cf. heterostylous.
host: an organism on which a parasite lives and by which it is nourished; also applied to a plant supporting an epiphyte.
hybrid: the offspring of genetically different parents (in a flora, usually applied where the parents are of different species).
hybrid swarm: a variable population resulting from crossing and segregation amongst the offspring of a hybrid or hybrids, including one or both of the parent taxa.
hydrophyte: a plant growing submerged in water, sometimes partly emergent.
hygroscopic: capable of expanding or contracting in response to presence or absence of water or atmospheric moisture.
hypanthium: a cup-like or tubular structure formed above the base, and often above the top, of the ovary with the stamens and perianth parts inserted on the rim. e.g. as in Onagraceae and some Myrtaceae. Fig. 12 D.
hypocotyl: the part of the stem of an embryo or young seedling below the cotyledonary node.
hypodermis: a layer of cells below the epidermis.
hypogynous: inserted below the level of the ovary, e.g. of sepals, petals and stamens. Fig. 12 A. cf. perigynous, epigynous.
hypogeal: of germination, having the cotyledon(s) remaining within the seed coat. cf. epigeal.
hypopeltate: of an anther that is dorsifixed (or peltate) and in which the part of the anther that is prolonged downwards beyond the attachment point of the filament faces outwards in relation to the centre of the flower. cf. epipeltate.
hypostomatic: leaves with stomates on one surface only; usually on the lower surface. cf. amphistomatic.
imbricate: (1) of perianth parts, having their edges overlapping in the bud, see aestivation, Fig. 11 F; (2) of leaves, closely packed and overlapping, Fig. 2 H.
imparipinnate: term describing a pinnate leaf with a single terminal leaflet, and therefore usually with an odd number of leaflets. Fig. 3 C. cf. paripinnate.
in: in nomenclature, where the preceding author published the name in an article or book, authored or edited by the succeeding author.
incised: cut deeply, sharply and often irregularly (an intermediate condition between toothed and lobed).
inclined: orientated at an angle of 45-80°.
included: enclosed, not protruding, e.g. of stamens not projecting beyond the perianth or of valves which do not extend beyond the rim of a capsular fruit. cf. exserted.
incumbent: resting or lying upon.
incurved: of leaf margins, curved inwards or upwards. Fig. 10 B. cf. recurved, involute.
indefinite: variable in number; numerous; of an inflorescence, not terminating in a flower.
indehiscent: not opening at maturity to release seed or pollen.
indeterminate: (1) term describing growth or branching in which the terminal bud persists and produces successive lateral branches; (2) of an inflorescence of part of an inflorescence (=blastotelic), not ending in a flower, i.e. ending in a non-floral bud, e.g. a thyrse, raceme or spike, Fig. 17 C, H & I. cf. determinate.
indigenous: native to the area; not introduced. cf. endemic.
indumentum: a general term for the hairy or scaly covering of plants.
induplicate: of perianth parts, having their edges folded inwards in bud, but without overlapping, see aestivation. Fig. 11 H.
indusium: (1) the tissue covering the sorus of a fern; (2) the pollen-cup of the style of some Goodeniaceae.
inferior ovary: an ovary below the level of attachment of the perianth parts and stamens and completely fused with the hypanthium or at most with a free summit (Fig. 12 B); if less fused see half-inferior (Fig. 12 C). The floral parts of a flower with such an ovary are said to be epigynous.
inflated: swollen; like a bladder.
inflexed: bent inwards.
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. Fig. 17.
infraspecific: of taxa, below the level of species
infructescence: the inflorescence in the fruiting stage; the arrangement of fruits, including peduncle, pedicels, bracts and fruit.
inrolled: rolled inwards; see revolute, involute.
insectivorous: trapping and feeding on insects and, by extension, other small invertebrates.
inserted (on): attached to; arising from.
integument: a covering; one of the outer layers of tissue of an ovule.
inter-: a prefix: between, as in interpetiolar stipule, a stipule between the petioles.
intercalary: of a meristem (growing region), situated between regions of permanent tissue, e.g. at the base of nodes and leaves in many monocotyledons.
intercotyledonary inclusion: group of cells or particles between cotyledons.
interfertile: able to interbreed.
intergeneric: between genera, e.g. hybridization.
interjugary: of glands, present on the rachises of bipinnate leaves between the junction of pairs of pinnae or of pinnules. as in some Acacia species. cf. jugary.
intermediate leaves: leaves that develop after the juvenile and before the mature leaves in plants which have dimorphic or trimorphic foliage.
internode: the portion of the stem between two successive nodes.
interpetiolar: of stipules, between the petiole bases of two opposite leaves. Fig. 4 J.
interrupted inflorescence: one with flowers in distinct clusters and with bare axis or stem between the clusters.
intracarinal: the surface between keels.
intramarginal: situated inside the margin but close to it, e.g. of veins in the leaves of many Myrtaceae.
intravaginal: of a tiller that grows within the subtending leaf sheath. cf. extravaginal.
intricate: of plants, with many entangled branches. Fig. 1 D.
introduced (exotic): not native to the area; not indigenous. cf. endemic.
introrse: of anthers, dehiscing towards the centre of the flower (check in bud!). cf. extrorse, latrorse.
invagination: the process of forming a pocket by turning in on itself, as in the floral axis of figs (e.g. Ficus species where the minute flowers and fruits are actually inside the swollen inflorescence stem, the ‘fig’); the resulting multiple fruit is a syconium. Fig. 18 Y.
involucre: (1) a whorl or several whorls of bracts surrounding a flower or an inflorescence (as around the head in many Asteraceae); (2) a layer of tissue enveloping a particular structure, such as sporangia in many ferns, e.g. Hymenophyllaceae.
involute: rolled inwards; of a leaf margin rolled upwards. Fig. 10 C. cf. revolute.
irregular: see zygomorphic.
irritable: responding suddenly to stimuli, e.g. the labellum of some orchids (family Orchidaceae) and trigger plants (family Stylidiaceae).
isobilateral (isolateral, similifacial): having structurally similar upper and lower surfaces. cf. dorsiventral.
isodiametric: of equal dimensions, e.g. a cube.
isotype: a specimen which is, or is believed to be, a duplicate of the holotype, i.e. part of the same collection.
joint: (1) an articulation, as in a 1-foliolate leaf, Fig. 3 I; (2) a segment of some cladodes, as in many Cactaceae; (3) a node.
jugary: of glands, present on the rachises of bipinnate leaves at the junctions of pairs of pinnae or of pinnules, as in some Acacia species. Fig. 19 H. cf. interjugary.
juvenile leaves: the first-formed leaves, especially when they differ from the adult leaves.
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