Glossary K - O

karyoevolution: evolutionary change in the chromosome set, expressed as changes in number and gross structure of the chromosomes; (more broadly), evolutionary relationships between taxa as indicated by karyotype differences.

karyotype: the gross morphology of the chromosome set, described in terms of number, length, centromere position, etc.

keel: a ridge like the keel of a boat; in particular, a boat-shaped structure formed by fusion of the two anterior petals of a flower in fabaceae.

keeled: of leaves or bracts, folded and ridged along the midrib.

labellum: a lip; in orchidaceae, the distinctive median petal that serves as an alighting platform for pollinating insects.

labellum: in zingiberaceae and costaceae, a usually showy petaloid structure, staminodal in origin.

laciniate: slashed into narrow, pointed lobes.

lacrymiform: tear-shaped, i.e. more or less ovoid or obovoid.

lacuna: a gap or cavity.

lamella: a thin, plate-like layer; middle lamella, the layer between the walls of two adjacent cells.

lamina: the blade of a leaf.

lanceolate: of a leaf, about four times as long as it is broad, broadest in the lower half and tapering towards the tip.

latex: a viscous fluid exuded from the cut surfaces of the leaves and stems of certain plants.

latiseptate: with broad partitions. cf. angustiseptate.

latrorse: of anthers, opening laterally towards adjacent anthers.

latrorse: turned sideways, i.e. not or away from axis.

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

lectotype: a specimen selected from among those cited with the original description to serve in place of a holotype where the holotype is missing or destroyed, or where no holotype was designated.

legume: a fruit characteristic of the families mimosaceae, caesalpiniaceae and fabaceae, formed from one carpel and either dehiscent along both sides, or indehiscent; in particular, an edible crop species in the family fabaceae.

lemma: the lower of two bracts enclosing a grass flower.

lenticel: a loosely-packed mass of cells in the bark of a woody plant, visible on the surface of a stem as a raised powdery spot, through which gaseous exchange occurs.

lenticular: shaped like a biconvex lens.

lepidote: covered with small, membranous scales.

leptocaul (= leptocladous):twiggy, with abundant, relatively slender branches.

leptosporangiate: of ferns, having sporangia with walls only one cell thick. cf. eusporangiate.

liane: a climbing or twining plant (usually applied to woody climbers).

lignified: converted into wood.

lignotuber: a woody swelling below or just above the ground, containing adventitious buds from which new shoots develop if the top of the plant is cut or burnt (common in the shrubby eucalypts and in many other fire-tolerant australian shrubs).

ligulate: bearing a ligule; strap-shaped.

ligule: a strap-shaped structure; a membranous, scarious or hairy appendage on the adaxial surface of a leaf, especially in gramineae, pteridophytes, palmae, zingiberaceae; the corolla limb in ray flowers of asteraceae.

limb: the upper, free, spreading portion of a corolla or perianth that is connate at the base.

linear: very narrow in relation to the length, and with the sides parallel.

lithophyte: a plant that grows on the surface of unweathered rock.

lobed: divided into lobes (rounded segments) separated from adjacent segments by sinuses which reach halfway or less to the middle of the organ. cf. cleft

lobulate: having small or indistinct lobes.

loculicidal: of the dehiscence of a fruit, along lines coinciding with the centres of loculi. cf. septicidal.

loculus: an enclosed compartment within an organ e.g. an ovary, an anther. pl. loculi.

lodicule: one of a pair of tiny scales in a grass floret, between the lemma and the fertile parts of the flower, which may be reduced perianth segments.

lomentum: a legume having distinct constrictions or lines of abscission between the seeds and breaking into one-seeded segments when mature.

lorate: of leaves, strap-shaped (moderately long with the two margins parallel).

lyrate: deeply lobed, with a large terminal lobe and smaller lateral ones.

macrospore: (=megaspore)

mallee: a growth form in eucalypts in which several stems arise from a lignotuber.

mallee: a growth habit in which several woody stems arise separately from a lignotuber (usually applied to shrubby eucalypts); a plant having the above growth habit.

mammillate: having small nipple-shaped projections.

marcescent: withering without falling off.

marginal: occurring at or very close to the margin.

medifixed: attached by or at the middle, e.g. of anthers, attached to the filament at the middle of the connective.

megagametophyte: a plant body or cell lineage, formed by vegetative growth of the megaspore, that produces the female gametes of a heterosporous plant.

megasporangium: the larger of the two kinds of sporangia produced in the sexual life cycle of a heterosporous plant.

megaspore: the larger of the two kinds of spores produced in the sexual life cycle of a heterosporous plant, giving rise to the female gametophyte.

megasporophyll: a specialised leaf upon (or in the axil of) which one or more megasporangia are borne.

meiosis: the two-stage division of a diploid nucleus, occurring once in every sexual life cycle, in which gene recombination occurs and the number of chromosomes characteristic of the sporophyte plant is halved prior to producing gametes.

mericarp: one segment of a fruit that breaks at maturity into units derived from the individual carpels. cf. schizocarp.

meristem: growing regions of a plant in which cells that have retained their embryonic characteristics, or reverted to them secondarily, divide to produce new cells.

mery: the number of parts per whorl that characterises a particular flower (generally constant for the perianth whorls and less often for the whorl(s) of stamens also). adj. merous. cf. trimerous

mesocarp: the fleshy portion of the wall of a succulent fruit inside the skin and outside the stony layer, if any, surrounding the seed(s).

mesophyll: photosynthetic tissue of a green plant; of vegetation, characteristic of moist habitats and with soft, fairly large leaves predominating; a leaf whose area is within the approximate range 20<180 square cm.

microgametophyte: a plant body or cell lineage, formed by vegetative growth of the microspore, that produces the male gametes of a heterosporous plant.

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

microsporangium: the smaller of the two kinds of sporangia produced in the sexual life cycle of a heterosporous plant.

microspore: the smaller of the two kinds of spores produced in the sexual life cycle of a heterosporous plant, giving rise to the male gametophyte.

microsporophyll: a specialised leaf upon (or in the axil of) which one or more microsporangia are borne.

midrib: the central, and usually the most prominent, vein of a leaf or leaf-like organ.

monadelphous: of stamens, united by their filaments into one bundle.

moniliform: contracted at short regular intervals like a string of beads.

moniliform: of hairs, constricted between the cells like a string of beads; of fruits, constricted between the seeds.

monocarpic: flowering and fruiting only once during its life span.

monochasium: a cymose inflorescence with the branches arising singly. cf. dichasium.

monochlamydeous: of a flower, having only one whorl of perianth parts.

monoclinus: having male and female reproductive organs in the same flower.

monocotyledon: a flowering plant whose embryo has only one cotyledon (seed leaf). cf. dicotyledon.

monoecious: having the male and female reproductive structures in separate flowers but on the same plant. cf. dioecious.

monophyletic: derived from a single ancestral line. cf. polyphyletic.

monopodial: of growth, with a persistent terminal growing point producing many lateral organs successively; of a stem, growing in the above manner. cf. sympodial

monotypic: containing only one taxon of the next lower rank (e.g. applied to a family containing only one genus). cf. polytypic.

morphology: the form and structure of an organism or part of an organism; the study of form and structure.

motile: actively moving; self-propelled.

mucilage: slimy material exuded by certain plants or plant organs. adj. mucilaginous.

mucro: a sharp, abrupt terminal point. adj. mucronate.

muricate: rough on the surface due to minute, hard outgrowths of the epidermis.

muricate: rough on the surface; covered with short, hard tubers.

muriculate: rough with minute, short, hard points.

mycorrhiza: a symbiotic union between a fungus and a plant root.

naked: of sporangia, not covered by an indusium; of seeds, exposed on the surface of a sporophyll (not enclosed within an ovary); of flowers, without perianth; of protoplasts or gametes, not bounded by a cell wall.

nectary: a gland that secretes nectar. adj. nectariferous.

neotype: a specimen selected to serve in place of a holotype where none of the material to which the name was originally applied is known to have been preserved.

nerve: a vein.

neuter: sterile (e.g. of flowers in which neither the androecium nor the gynoecium is functional in reproduction).

nocturnal: of flowers, opening only at night.

node: the level (transverse plane) of a stem at which one or more leaves arise.

nomen conservandum: a name of a family or genus (or taxon intermediate between these two) that has been formally accepted as the correct name contrary to the usual principles of botanical nomenclature.

nomen illegitimum: a name which, at the time of its publication, was superfluous (because the taxon to which it was applied had already been named) or had already been applied to another plant.

nomen nudum: a name published without a diagnosis or description of the entity to which it applies, and without reference to either.

nomen rejiciendum: a name rejected in favour of a 'nomen conservandum'.

nucellus: the central tissue of an ovule, within which the megaspore mother cell is formed.

nucleus: the central or original part around which other parts are formed.

nut: a hard, dry, indehiscent fruit formed from two or more carpels but containing only one seed.

obconical: cone-shaped but attached at the narrower end.

obcordate: of a leaf blade, broad and notched at the tip; heart-shaped but attached at the pointed end. cf. cordate

oblanceolate: similar in shape to lanceolate but attached at the narrower end.

obligate: of parasites, unable to survive without the host. cf. facultative.

oblique: of a leaf or leaflet, larger on one side of the midrib than on the other, i.e. asymmetrical.

obloid: (a three-dimensional shape) with short, parallel sides and rounded ends, as if composed of two hemispheres linked together by a very short cylinder.

oblong: having the length greater than the width but not many times greater, and the sides parallel.

obovate: similar in shape to ovate but attached at the narrower end.

obsolescent: non-functional but not reduced to a rudiment.

obsolete: reduced to a rudiment, or completely lacking. cf. rudimentary, vestigial.

obsolete: vestigial (or rudimentary).

obtuse: blunt or rounded at the apex, the converging edges separated by an angle greater than 90 degrees.

ochrea: a sheath, formed from two stipules, encircling the node in polygonaceae.

ontogeny: the development of a single organism, i.e. the sequence of stages through which it passes during its lifetime.

operculum: a lid or cover becoming detached at maturity by abscission; in Eucalyptus (for example), a cap covering the bud and formed by fusion or cohesion of perianth parts.

opposite: of leaves, borne at the same level but on opposite sides of the stem; of floral parts, on the same radius (as). cf. alternate.

orbicular: circular or nearly so.

order: a taxonomic grouping of families believed to be closely related (sometimes a single family with no apparent close relatives).

orthotropous: of an ovule, erect so that the micropyle points away from the placenta.

osmophore: a specialised flower part that secretes odours, usually to attract pollinators.

ostiole: an opening or pore, e.g. (in moraceae) at the apex of a fig, or (in fungi and lichens) at the apex of a perithecium. adj. ostiolar, ostiolate.

ovary: the basal portion of a carpel or group of fused carpels, enclosing the ovule(s).

ovate: shaped like a section through the long axis of an egg, and attached by the wider end. cf. ovoid.

ovoid: egg-shaped (in three dimensions). cf. ovate.

oval: similar to elliptic but more rounded at the base and tip.

ovulate: with ovules.

ovule: a structure in a seed plant within which one or more megaspores are formed and which develops into a seed after fertilisation.

ovuliferous: bearing ovules (e.g. applied to scales in a megasporangiate cone in gymnosperms).

ovulode: sterile structures on the placenta.