Australian Biological Resources Study
Compiled by A.McCusker
palea: in a grass floret, the upper one of the two bracts enclosing a flower.
palmatifid: of a leaf, deeply (but not completely) divided into several lobes which arise (almost) at the same level. cf. pinnatifid. > image <
palmatinerved: of leaves, palmately nerved, i.e. with the (main) nerves radiating from one basal point.
palmatisect: a condition intermediate between palmate and palmatifid, with the green tissue of the lamina completely divided into several segments, but the segments not fully separated at the base. > image <
palynology: the scientific study of pollen.
panicle: a compound raceme; an indeterminate inflorescence in which the flowers are borne on branches of the main axis or on further branches of these. > image <
paniculate: indeterminate and much branched.
pantoporate: of a pollen grain, with rounded apertures all over the surface.
papilla: a small, elongated protuberance on the surface of an organ, usually an extension of one epidermal cell. adj. papillose. > image <
pappus: a tuft of hairs on a fruit; in Asteraceae, a tuft (or ring) of hairs or scales borne above the ovary and outside the corolla and possibly representing the calyx. > image <
parapatric: of distributions of two taxa or populations, having non-overlapping but contiguous ranges. cf. allopatric, sympatric.
paraphyletic: a group of taxa derived from a single ancestral taxon, but which does not contain all the descendants of the most recent common ancestor.
paraphyses: sterile filaments in the fruiting bodies of non-vascular plants.
parasite: an organism living on or in a different organism and deriving nourishment from it. cf. autotrophic, epiphyte, saprophyte. > image <
paratype: a specimen or illustration, other than the holotype, isotype or one of the syntypes, that was cited with the original publication of a name. cf. type.
parenchyma: plant tissue consisting of mature, living cells that are relatively unspecialised in function.
parietal: attached to the margins of a structure; of placentation, having the ovules attached to placentas on the wall of the ovary. > image <
paripinnate: having an even number of pinnae by virtue of having a pair in the terminal position. cf. imparipinnate. > image <
-partite: divided, almost to the base, into segments (commonly applied to a style or leaf).
pedate: of a palmate or palmately-lobed leaf, having the lateral segments divided again.
pedicel: the stalk of a flower. adj. pedicellate. > image <
peduncle: the stalk of an inflorescence; in ferns, the stalk of a sporocarp. adj. pedunculate.
peloric: actinomorphic, of a flower which, from its taxonomic context, would be expected to be zygomorphic, e.g. in Orchidaceae. cf. actinomorphic, zygomorphic.
pendulous: drooping; of ovules, attached at the top of the ovary and hanging downwards from an apical placenta.
penicillate: pencil-shaped; tufted like an artist's brush.
penninerved (= penniveined): having conspicuous lateral veins divergent from the midrib and lying approximately parallel to each other.
pentamerous: of a flower, having five segments in each perianth whorl, and usually five in each whorl of stamens also.
pepo: a fruit with firm skin, pulpy interior, many seeds and a single locule; species epithet for a group of cucurbits including squash, zucchini and some pumpkins and gourds.
perennate: maintain a dormant, vegetative state throughout non-growing seasons.
perennial: a plant whose life span extends over more than two growing seasons. cf. annual, biennial.
perfoliate: of a sessile leaf or bract, having its base completely wrapped around the stem. > image <
perianth: the calyx and corolla of a flower, especially where the two are similar. > image <
pericarp: the wall of a fruit, developed from the ovary wall.
perigynous: of perianth segments and stamens, arising from a cup or tube (hypanthium) that is free from the ovary but extending above its base. cf. epigynous, hypogynous. > image <
perisperm: nutritive tissue in an angiospermous seed, formed from the nucellus. cf. endosperm.
persistent: remaining attached to the plant beyond the expected time of falling, e.g. of sepals not falling after flowering.
petal: a member of the inner whorl of non-fertile parts surrounding the fertile organs of a flower, usually soft and coloured conspicuously. > image <
petaloid: like a petal; soft in texture and coloured conspicuously.
petiolule: the stalk of a leaflet.
phalange: a bundle comprising several structures fused together; a group of connate carpels, e.g. in Pandanaceae.
phanerogam: (literally) a plant with conspicuous reproductive parts; a plant reproducing by seeds. cf. cryptogam.
phenotype: the physical characteristics of an organism; the outward expression of characteristics conferred on an organism by its genotype. cf. genotype.
phloem: the tissue in the conducting system of a plant through which metabolites (products of chemical reactions in the plant) are transported.
phyllichnium: in Casuarinaceae, the ridge of a branchlet segment; pl. phyllichnia.
phylloclade: a very leaf-like, photosynthetic stem of a plant whose true leaves are much reduced. cf. cladophyll.
phyllode: a leaf whose blade is much reduced or absent, and whose petiole and rachis have assumed the functions of the whole leaf. cf. cladode.
phyllotaxy: the arrangement of leaves on a stem (when spiral, often expressed quantitatively as the fraction of the circumference of the stem that separates two successive leaves). > image <
phylogeny: the evolutionary development of a plant group, i.e. its derivation from its ancestors and the relationship among its members. adj. phylogenetic.
phylum: an alternate name for division, the major taxonomic rank below Kingdom.
pilose: hairy, the hairs soft and clearly separated but not sparse.
pinna: a primary segment of the blade of a compound leaf. pl. pinnae.
pinnatifid: cut deeply (but not to midrib) into lobes that are spaced out along the axis (of the leaf). cf. palmatifid, ternatifid. > image <
pinnatipartite: of leaves, pinnatifid, where the lobes pass beyond the middle (or are within the middle third) and the parenchyma is not interrupted.
pinnatisect: dissected down to the midrib but having the segments confluent with it. > image <
pinnule: a leaflet of a bipinnate leaf.
pistil: a free carpel or a group of fused carpels.
pistillode: a sterile pistil, often rudimentary.
pith: the central region of a stem, inside the vascular cylinder.
placenta: a region, within an ovary, to which ovules are attached.
placentation: the arrangement of placentas, and hence of ovules, within an ovary. > image <
plesiomorphic: of a character, ancestral or primitive. cf. apomorphic.
plicate: folded back and forth longitudinally like a fan. > image <
plietesial: monocarpic but living for several years before flowering.
plumose: like a feather; with fine hairs branching from a central axis.
plumule: the portion of an embryo that gives rise to the shoot system (as distinct from the root system) of a plant. cf. radicle.
pneumatophore: an air-vessel; an organ containing aerenchyma; in particular, a root of a mangrove plant, growing above the substratum.
pod: a leguminous fruit. > image <
pollen: the microspores of seed plants; the powdery mass of microspores shed from anthers.
pollen-grain: a microspore of a seed plant, or the partially developed gametophyte formed from it.
pollen presenter: of many Proteaceae, a structural modification, usually a swelling, of the style around or below the stigma which enables pollen, shed in the bud, to be retained.
pollen-sac: a cavity, in an anther, in which pollen is formed.
pollination: the transfer of pollen from the male organ, where it is formed, to the receptive region of a female organ, e.g. from anther to stigma.
pollinarium: the complex structure found in flowers of Asclepiadaceae and Orchidaceae where the pollen masses of the two adjacent anther-lobes (thecae) are united for dispersal as a unit. The pollinarium consists of two pollinia, attached by caudicles to a central corpusculum. pl. pollinaria.
pollinium: pollen-mass, the aggregation of all the pollen of one anther-lobe (theca) into one unit for transfer in pollination. pl. pollinia.
polygamodioecious: with bisexual and male flowers on some plants, and bisexual and female flowers on others.
polygamomonoecious: with bisexual flowers and unisexual flowers of both sexes on the same plant.
polygamous: having bisexual and unisexual flowers on the same or different plants.
polymorphic: having more than two distinct morphological variants.
polypetalous: with free petals. cf. sympetalous.
polyphyletic: composed of members that originated, independently, from more than one evolutionary line. cf. monophyletic.
polyploid: having more than two of the basic sets of chromosomes in the nucleus. cf. diploid, haploid.
polytypic: containing more than one taxon of the next lower rank, e.g. applied to a family containing more than one genus. cf. monotypic.
pome: a fleshy (false) fruit, formed from an inferior ovary, in which the receptacle or hypanthium has enlarged to enclose the true fruit.
porate: of a pollen grain, with rounded apertures (called pores) only. cf. colporate, colpate.
poricidal: of anthers or capsules, opening by pores. > image <
porrect: of a trichome, having branches spreading more or less horizontally from the top of an erect stalk.
posterior: of floral organs, on the side of the flower nearest to the axis. cf. anterior.
praemorse: appearing bitten off at the end.
prickle: a hard, pointed outgrowth from the surface of a plant, involving several layers of cells but not containing a vein. > image <
process: as part of a plant, a projecting outgrowth or appendage.
procumbent: trailing or spreading along the ground but not rooting at the nodes.
proliferous: able to reproduce vegetatively from the shoot system, e.g. by stems rooting at the nodes (as in Conostylis); producing plantlets on leaves or fronds (Pteris) or in the inflorescence (Isolepis).
propagule: a structure with the capacity to give rise to a new plant, e.g. a seed, a spore, part of the vegetative body capable of independent growth if detached from the parent.
prophyll: a leaf formed at the base of a shoot, usually smaller than those formed subsequently.
prostrate: lying flat on the ground.
protandrous: having the male sex organs maturing before the female; of a flower, shedding the pollen before the stigma is receptive. cf. protogynous.
prothallus: a gametophyte body, especially in bryophytes, ferns and related plants.
protogynous: having the female sex organs maturing before the male; of a flower, shedding the pollen after the stigma has ceased to be receptive. cf. protandrous.
proximal: near to the point of origin or attachment. cf. distal.
pruinose: having a whitish, waxy, powdery bloom on the surface.
pseudanthium: a compact inflorescence of several to many small flowers which simulates a single flower.
pseudo-: false; apparent but not genuine.
ptyxis: pattern of folding and rolling shown during leaf development.
puberulous: covered with minute, soft, erect hairs.
pubescent: covered with short, soft, erect hairs.
pulverulent: appearing as though dusted over with powder.
pulvinate: cushion- or pad-shaped, resembling a pulvinus.
pulvinus: a swelling at the base of the stalk of a leaf or leaflet, often glandular or responsive to touch. > image <
punctate: marked with dots.
puncticulate: minutely dotted.
pungent: ending in a stiff, sharp point; having an acrid taste or smell.
pustulate: covered with small pustule- or blister-like elevations.
pyrene: the 'stone' (endocarp plus seed) of a succulent fruit. cf. berry, drupe.
quincuncial: of the arrangement of corolla lobes in a bud, a variant of imbricate aestivation.