Glossary of Botanical Terms - P

P

palea

(plural paleae)

1. the upper of 2 bracts enclosing a grass flower, major contributors to chaff in harvested grain.

2. Chaffy scales on the receptacles of many Asteraceae.

3. Chaffy scales on the stipe of many ferns.

paleate

bearing paleae or chaffy scales, as in description of the receptacle of a capitulum of a plant in the Asteraceae.

paleaceous

Chaff-like in texture.

palmate

1. a compound leaf divided into several leaflets arising from the same point at the top of the petiole.

2. of veins in a simple leaf when they arise in a similar fashion.

palmatifid

deeply divided into several lobes arising from more or less the same level.

palmatisect

intermediate between palmate and palmatifid, i.e. the segments are not fully separated at the base; often more or less digitate.

panicle

(adjective paniculate) a compound raceme; an indeterminate inflorescence in which the flowers are borne on branches of the main axis or on further branches of these.

papilionate

butterfly-like; with a corolla like that of a pea.

papilla

(plural papillae, adjective papillose) a small, elongated protuberance on the surface of an organ, usually an extension of one epidermal cell.

pappus

in daisy florets, a tuft or ring of hairs or scales borne above the ovary and outside the corolla (representing the missing calyx); a tuft of hairs on a fruit.

parasite

an organism living on or in a different organism, from which it derives nourishment; compare saprophyte, epiphyte.

parietal

attached to the marginal walls of a structure, for example ovules attached to placentas on the wall of the ovary. See Placentation.

paripinnate

having an even number of leaflets (or pinnae), that is terminated by a pair of pinnae as opposed to a single pinna; compare imparipinnate.

patent

of plants, spreading.

pectinate

pinnately divided with narrow segments closely set like the teeth of a comb.

pedate

with a terminal lobe or leaflet, and on either side of it an axis curving outwards and backwards, bearing lobe or leaflets on the outer side of the curve.

pedicel

(adjective pedicellate) the stalk of a flower.

peduncle

(adjective pedunculate) the stalk of an inflorescence.

peltate

shield-like; with stalk attached to the lower surface and not to the margin.

pellucid

transmitting light; for example, said of tiny dots in leaves visible when held in front of light.

pendulous

hanging, for example an ovule attached to a placenta on the top of the ovary; compare suspended.

penicillate

tufted like an artist's brush; with long hairs towards one end.

penninervation (penninerved)

with pinnately arranged veins.

pepo

type of berry formed from an inferior ovary and containing many seeds, usually large with a tough outer skin, for instance, pumpkin, cucumber.

perennating

of an organ that survives vegetatively from season to season. A period of reduced activity between seasons is usual.

perennial

a plant whose life span extends over several years.

perfect

of a flower, when bisexual.

perfoliate

with its base wrapped around the stem (so that the stem appears to pass through it), e.g. of leaves and bracts.

perianth

the collective terms for the calyx and corolla of a flower (generally used when the two are similar).

pericarp

the wall of a fruit, developed from the ovary wall.

perigonium

1. in flowering plants, the petals and sepals, the perianth

2. in bryophytes, the leaves surrounding the antheridia, the perianth, also called a splash cup

perigynous

borne around the ovary, i.e. of perianth segments and stamens arising from a cup-like or tubular extension of receptacle (free from the ovary but extending above its base); cf. epigynous, hypogynous.

persistent

remaining attached to the plant beyond the usual time of falling, for instance sepals not falling after flowering, flower parts remaining through maturity of fruit; compare deciduous, caducous.

perule

1. the scaly covering of a leaf or flower bud.

2. in camellias the final bracts and sepals become indistinguishable and are called perules.

3. a kind of sac formed by the adherent bases of the two lateral sepals in certain orchids.

petal

in a flower, one of the segments or divisions of the inner whorl of non-fertile parts surrounding the fertile organs, usually soft and conspicuously coloured; compare sepal.

petaloid

like a petal; soft in texture and coloured conspicuously.

petiolate

subtended by a petiole.

petiole

the stalk of a leaf.

petiolule

the stalk of a leaflet.

petricolous

Rock-dwelling; living on or among rocks.

phanerogam

gymnosperms and angiosperms; plants producing stamens and gynoecia; literally plants with conspicuous sexual reproductive organs; cf. cryptogams.

photosynthesis

the process by which sugars are made from carbon dioxide and water in cells containing chloroplasts; the chemical energy required from solar energy in the presence of the pigment chlorophyll.

phyllode

(adjective phyllodineous) a leaf with the blade much reduced or absent, and in which the petiole and or rachis perform the functions of the whole leaf; e.g. many acacias; cf. cladode.

phyllopodium

the part of the stipe that is proximal or basal of the articulation (joint) and remains attached to the rhizome after the frond has detached from the articulation; especially prominent in Elaphoglossum and Oleandra.

phytomelan

a black, inert, carbonaceous material that lacks nitrogen, probably derived from catechol, that forms a crust-like covering of some seeds, commonly found in Asparagales, Asteraceae, etc.

pilose

covered with soft, weak, thin and clearly separated hairs, which are usually defined as long and sometimes ascending.

pinna

(plural pinnae) a primary segment of a compound leaf.

pinnate

a compound leaf with leaflets arranged on each side of a common petiole or axis; also applied to how the lateral veins are arranged in relation to the main vein.

pinnatifid

pinnately lobed.

pinnatisect

pinnately divided almost to midrib but segments still confluent.

pinnule

ultimate free division (or leaflet) of a compound leaf, or a pinnate subdivision of a multipinnate leaf.

pistil

1. a single carpel when the carpels are free.

2. a group of carpels when the carpels are united by the fusion of their walls.

pith

the central region of a stem, inside the vascular cylinder; the spongy parenchymatous central tissue in some stems and roots.

placenta

the tissue within an ovary to which the ovules are attached.

placentation

the arrangement of ovules inside ovary; for example axile, free-central, parietal, marginal, basal, or apical.

Plant Breeders Rights (PBR)

these rights, governed by Plant Breeder's Rights Acts give the plant breeder legal protection over the propagation of a cultivar, and the exclusive rights to produce and to sell it, including the right to license others to produce and sell plants and reproductive material of a registered, deliberately bred variety. Cf. UPOV.

Plant Variety Rights (PVR)

governed by the Plant Variety Rights the registration of new varieties is now governed by Plant Breeders Rights.

Plastochron

the time between successive leaf initiation events.

plicate

pleated; folded back and forth longitudinally like a fan, such as the leaves of many palm species. (The concept often appears in specific names in forms such as Aloe plicatilis and Acacia plicata. Commonly such names are not correctly appropriate, but are applied to distichous structures rather than plicate.

-plinerved

(of leaves) a suffix indicating that the main nerves are lateral and arise from a point distinctly above the base of the leaf. Combined with a numerical prefix to form words like 3-plinerved, 5-plinerved, and so on. Such leaves are especially characteristic of the family Melastomataceae.

plumose

like a feather; with fine hairs branching from a main axis.

plumule

the part of an embryo that gives rise to the shoot system of a plant; cf. radicle.

pneumatophore

a vertical, aerial (at low tide) appendage to the roots of some plants, through which gases are exchanged; e.g. on mangroves.

pod

1. a legume, the fruit of a leguminous plant, a dry fruit of a single carpel, splitting along two sutures.

2. siliqua and silicula, the fruit of Brassicaceae, a dry fruit composed of two carpels separated by a partition.

pollen

powdery mass shed from anthers (of angiosperms) or microsporangia (of gymnosperms); the microspores of seed plants; pollen-grains.

pollen-mass

pollen-grains cohering by a waxy texture or fine threads into a single body; pollinium; e.g. in orchids.

pollination

the transfer of pollen from the male organ (anther) to the receptive region of a female organ (stigma).

pollinium

see pollen-mass.

polygamodioecious

having bisexual and male flowers on some plants and bisexual and female flowers on others; cf. androdioecious, andromonoecious, dioecious, monoecious, polygamomonoecious, polygamous.

polygamomonoecious

having male, female and bisexual flowers on the same plant; cf. androdioecious, andromonoecious, polygamodioecious, polygamous.

polygamous

having bisexual and unisexual flowers on the same plant.

polymorphic

of several different kinds (in respect to shape and/or size).

polyploid

with more than two of the basic sets of chromosomes in the nucleus; any individual (or a cell) containing three or more complete sets of chromosomes. Various combinations of words or numbers with '-ploid' indicate the number of haploid sets of chromosomes; e.g. triploid = 3 sets, tetraploid = 4 sets, pentaploid = 5 sets, hexaploid = 6 sets, and so on.

pome

a fruit that has developed partly from the ovary wall but mostly from the floral tube, e.g., apple.

population

1. all individuals of one or more species within a prescribed area.

2. a group of organisms of one species, occupying a defined area and usually isolated to some degree from other similar groups.

3. in statistics, the whole group of items or individuals under investigation.

posterior

the side nearest the axis; compare anterior.

prickle

(adjective: prickly) hard, pointed outgrowth from the surface of a plant (involving several layers of cells but not containing a vein); sharp outgrowth from the bark, detachable without tearing wood; cf. thorn.

prophyll

a leaf formed at the base of a shoot, usually smaller than those formed later.

pro parte

(Latin) in part; in nomenclature, to denote that the preceding taxon includes more than one currently recognized entity, and that only one of those entities is being considered.

procumbent

spreading along the ground but not rooting at the nodes: not as close to ground as prostrate.

propagules

a structure capable of producing a new plant; includes seeds, spores, bulbils, etc.

prostrate

lying flat on the ground.

protandrous

male sex organs maturing before the female ones, e.g. a flower shedding pollen before the stigma is receptive; cf. protogynous.

prothallus

a gametophyte body, usually flattened and delicate; e.g. in ferns and fern allies.

protogynous

female sex organs maturing before the male ones, e.g. a flower shedding pollen after the stigma has ceased to be receptive; cf. protandrous.

proximal

near the point of origin or attachment; cf. distal.

pruinose

covered with a powdery, waxy material; with a bloom.

pseudanthium

a particular form of inflorescence occurring in many species of the Asteraceae, in which multiple flowers are grouped together to form a flower-like structure, commonly called a head or capitulum.

pseudo

false; apparently but not genuine; e.g. pseudo-bulb = a thickened, bulb-like internode in orchids, or a corm.

pseudostipule

an enlarged, persistent axillary bud scale that resembles a stipule; common in Bignoniaceae.

puberulous (puberulent)

covered with minute soft erect hairs.

pubescent

downy; covered with short, soft, erect hairs.

pulvinus

a swelling at the base of a leaf or leaflet stalk, often glandular or responsive to touch.

punctate

marked with dots.

pungent

having a sharp hard point.

pyramidal

of a plant's form, tetrahedral, pyramid-shaped.

pyrene

the stone of a drupe, consisting of the seed surrounded by the hardened endocarp.

pyriform

pear-shaped.