p.p.: (pro parte, Latin) in part; in nomenclature, to denote that the preceding taxon includes more than 1 currently recognized entity, and only 1 of those entities is being considered.
pachymorph: applied to the rhizome systems of some bamboos where growth is determinate and sympodial, the plants forming large clumps with short rhizomes, the culms arising terminally from the rhizomes and new rhizomes arising laterally.
packing bracts: bracts that fill out the spaces between flowers and form the surface of the spike, as in Xanthorrhoea species.
palea: (1) the upper of 2 bracts enclosing the flower of a grass; (2) one of the chaffy scales on the petiole and rachis of many ferns.
palmate (digitate): (1) of a compound leaf with 3 or more leaflets arising from the one point at the top of the petiole, Fig. 3 E & L; (2) of veins in a lamina, radiating from the one point, Fig. 9 C & D. adv. palmately.
palmately trifoliolate: of a leaf, with 3 leaflets arranged palmately, i.e. all the petiolules of about the same length. Fig. 3 L. cf. pinnately trifoliolate.
palmatifid: of a leaf cut into lobes to less than halfway in a palmate form. Fig. 5 U.
palmatisect: of a leaf cut into lobes to more than halfway in a palmate form. Fig. 5 V.
palmativeined: of leaves, palmately veined, i.e. with the (main) veins radiating from one basal point.
palynology: the scientific study of pollen.
panicle: a compound inflorescence with a main axis and lateral branches which are further branched, and in which each axis ends in a flower or flower bud. Fig. 17 A. adj. paniculate.
papilionaceous: (papilionate) butterfly-like; with a corolla like that of a pea, as in the family Fabaceae subfamily Faboideae.
papilla: a small elongated or nipple-shaped protuberance on an organ. pl. papillae.
papillose: of a surface, rough with papillae. Fig. 16 D.
pappus: the group of appendages, usually hairs or scales, above the ovary and outside the corolla in Asteraceae (possibly a modified calyx); often persisting on the fruit and aiding in its dispersal.
parallel: of veins in a lamina, all running in the same direction and equally distant from one another, as in grass leaves. Fig. 9 F.
paraphysis: a sterile filament occurring amongst the sporangia of some ferns. pl. paraphyses.
parasite: an organism growing and feeding upon another organism (the host). A hemiparasite is partly parasitic, partly autotrophic, and has some chlorophyll.
paratype: a specimen or illustration, other than the holotype, that was cited with the original publication of a name.
parenchyma: plant tissue consisting of mature, living cells that are relatively unspecialised in function.
parietal: (1) attached to the wall; (2) of placentation, with placentas on the wall or intruding partitions of a unilocular compound ovary, Fig. 13 B.
paripinnate: term describing a pinnately compound leaf without a single terminal leaflet, and therefore usually with an even number of leaflets. Fig. 3 D. cf. imparipinnate.
partial inflorescence: a portion of an inflorescence, particularly a part sufficiently branched to show the same structural plan as the inflorescence as a whole.
patelliform: knee-shaped; shaped like a small dish, circular and rimmed.
pedate: term describing a palmately compound leaf with the lateral leaflets divided again. Fig. 3 F. cf. ternate.
pedicel: the stalk of a flower (above the subtending bract or leaf); bracteoles are sometimes present on a pedicel.
peduncle: the stalk of an inflorescence
peltate: term describing an organ with a stalk or point of attachment on its lower surface away from the margin, often umbrella-like; e.g. leaves (Fig. 4 A), scales (Fig. 15 H).
pendent (pendulous): drooping, hanging downwards; e.g. of a shrub,. Fig. 1 O; of an ovule hanging from the top of the ovary, i.e. in an apical position. Fig. 13 G.
pendulous: see pendent.
penicillate: pinnately arranged veins in which the secondary veins are conspicuous and numerous and are more or less parallel to each other, as in a feather.
penniveined: pinnately arranged veins in which the secondary veins are conspicuous and numerous and are more or less parallel to each other, as in a feather.
pentamerous: of a flower, having five parts in each floral whorl (not necessarily including the gynoecium).
pepo: a fruit with firm skin, pulpy interior, many-seeded and a single loculus, derived from an inferior ovary, e.g. a pumpkin.
perennating: (of a plant) remaining alive for several years; (of an organ) a vegetative part that assists a plant to perennate.
perennial: a plant whose life-span extends over more than one growing season. cf. biennial, annual.
perfoliate: of a sessile leaf or bract, having its base completely surrounding the stem. Fig. 4 F.
perianth: the calyx and corolla collectively; especially when they are similar, individual segments then being called tepals.
pericarp: the wall of the fruit, developed from the ovary wall. cf. endocarp, exocarp, mesocarp.
perigynous: term describing sepals, petals and stamens that are attached to the rim of a lateral or upward expansion of the receptacle, or attached to the rim of a hypanthium which is not fused to the ovary. Fig. 12 D.
perisperm: nutritive tissue within the seed which is formed outside the embryo sac, lies between the embryo sac and the testa. cf. endosperm.
pers. comm.: personal communication; information gained from other than published sources.
persistent: remaining until the part that bears it is fully matured, e.g. of floral parts remaining until fruit is mature; of a leaf base, remaining attached to the plant after the leaf or frond has been shed.
petal: a free segment of the corolla.
petaline: of the petals, e.g. petaline calyptra, the calyptra formed from petals.
petaloid: resembling a petal, especially in colour and texture.
petiole: the stalk of a leaf. adj. petiolate. Fig. 4 B.
petiolule: the stalk of a leaflet. See also terminal petiolule.
phanerogam: a plant with conspicuous reproductive parts; a plat 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.
pheromone: a substance that attracts certain insects, as in the discharge from osmophores.
phloem: the tissue in the conducting system of a plant through which metabolites (products of chemical reactions in the plant) are transported. cf. xylem.
phyllary: an involucral bract of the Asteraceae, collectively the phyllaries surrounding a head form the calyculus.
phyllichnium: in family Casuarinaceae, the ridge of a branchlet article. pl. phyllichnia.
phyllode: a flattened petiole, leaf-like in appearance and function, replacing the lamina, as in many wattles.
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).
phylogeny: the evolutionary development of a plant group, i.e. its derivation from its ancestors and the relationship among its members. adj. phylogenetic.
phylum: a taxon of high rank, the major unit of classification. cf. division
pilose: hairy with long soft weak hairs which are clearly separated but not sparse. Fig. 14 H.
pinna: a primary segment of the lamina of a compound leaf. pl. pinnae.
pinnate: (1) (1-pinnate) of a leaf, with the lamina divided into pinnae in 2 rows along a rachis, once compound (Fig. 3 C & D) see imparipinnate, paripinnate. cf. bipinnate, tripinnate; (2) of veins, with the secondary veins arranged regularly (Fig. 9 A) cf. penniveined. adv. pinnately.
pinnately trifoliolate: of a leaf, with three leaflets arranged pinnately, i.e. the terminal petiolule usually jointed and longer than the lateral ones. Fig. 3 K. cf. palmately trifoliolate.
pinnatifid: of simple leaves or leaflets, of the lamina cut into lobes on both sides of the midrib. Fig. 5 R. cf. pinnatisect.
pinnatisect: of simple leaves or leaflets, of the lamina cut down almost to the midrib but having the segments confluent with it. e.g. as in the ultimate segments of some fern fronds. Fig. 5 S. cf. pinnatifid.
pinnule: a leaflet of a bipinnate leaf. pl. pinnules.
pistil: a free carpel or a group of fused carpels. See gynoecium.
pistillate: with a female flower.
pistillode: a rudimentary pistil present in some male flowers.
pith: the centremost tissue of a stem, often soft and spongy.
pitted: having numerous small depressions on the surface.
placenta: the part of the ovary to which the ovules are attached.
placentation: the arrangement of the placentas and the attached ovules. Fig.13.
plagiotropic: mode of growth of lateral branches, growing horizontally away from the leading shoot and maintaining a different morphology, as in some conifers. cf. orthotropic.
plano-convex: with upper surface convex, lower surface more or less flat. Fig. 10 A.
plicate: longitudinally folded. Fig. 11 I.
-ploid: suffix; multiple of a single basic set of chromosomes in the nucleus; e.g. haploid = 1 set, diploid = 2 sets; see also polyploid.
plumose: feather-like, with a central axis and fine hairs arising from it; e.g. (1) the styles in Clematis species, (2) the pappus of some Asteraceae, Fig. 15 K.
plumule: the shoot of the embryo.
pluritubulose: organs with several to many transverse as well as several longitudinal septa (seen by splitting the organ). cf. unitubulose.
pneumatophores: specialized vertical roots produced by some vascular plants which grow in water, water-logged mud or tidal swamps; the roots contain spongy tissue which enables them to exchange gases with the atmosphere through lenticels in their aerial portions, as in many mangroves.
pod: a legume or superficially similar fruit. Fig. 18 I.
pollen: the microspores of seed plants, formed in and shed from the anthers, by which time some nuclear division has taken place to form a gametophyte enclosed in the spore wall.
pollination: the transference of pollen from the anther to the stigma of flowers, and from the microsporangium to the pollen chamber of conifers and cycads.
pollinium: a mass of pollen grains cohering by means of their wavy texture or fine threads, as in Asclepiadaceae. pl. pollinia.
polygamodioecious: of plants, having bisexual and male flowers in some plants and bisexual and female flowers on others. cf. androdioecious, andromonoecious, dioecious, monoecious, polygamomonoecious, polygamous.
polygamomonoecious: of plants, having bisexual and unisexual flowers on the same plant. cf. androdioecious, andromonoecious, dioecious, monoecious, polygamodioecious, polygamous.
polygamous: having bisexual and unisexual flowers on the same plant.
polymorphic: displaying a number of varieties of form.
polypetalous: with free petals. cf. gamopetalous.
polyphyletic: composed of members that originated, independently, from more than one evolutionary line. cf. monophyletic.
polyploid: having more than two lots of the basic set of chromosomes in the nucleus. cf. diploid, haploid.
pome: a fleshy false fruit, formed from an inferior ovary, in which the hypanthium has enlarged to enclose the true fruit, as in Malaceae. Fig. 18 C.
poricidal: opening by pores, e.g. of anthers (Fig. 20 E) or capsules (Fig. 18 N).
porrect: pointed outward.
posterior: toward the axis, away from the subtending bract. cf. anterior.
praemorse: as though the end were bitten off, coarsely erose.
prickle: a hard, pointed outgrowth from the surface of a plant, involving several layers of cells, but not containing a vascular system. Fig. 14 O. adj. prickly. cf. spine, bristle.
proboscis: a snout, a surface projection.
probract: small, leaf-like structure at the base of an inflorescence in family Cucurbitaceae, usually arising opposite a tendril.
processes: outgrowths or projections from a surface.
procumbent: having stems trailing or spreading over the ground. Fig. 1 K.
proliferous: plants which bear adventitious buds on the leaves or flowers, such buds being capable of rooting and forming separate plants. e.g. bulbils, epiphyllous plantlets.
propagule: a structure with the capacity to give rise to a new plant, e.g. (1) a seed, (2) part of the vegetative body capable of independent growth if detached from the plant.
prophyll(s): the first leaf or pair of leaves of a shoot, in some monocotyledons delicate and not differentiated into blade and sheath.
prostrate: lying flat on the ground. Fig. 1 L.
protandrous: of a flower, shedding pollen before the stigma is receptive.
prothallus: the gametophyte stage of ferns and fern allies; usually flattened and delicate.
protogynous: of a flower, with the stigma becoming receptive and ceasing to be receptive before the pollen is shed.
protuberance: a prominently raised area on the surface of an organ, e.g. on bracteoles (as in family Casuarinaceae).
proximal: near to the point of origin or attachment. cf. distal.
pruinose: of a surface, having a waxy bloom that may be rubbed off. cf. glaucous.
pseudanthium: a condensed inflorescence unit in which several flowers resemble a single flower, as in Centrolepis.
pseudo-: a prefix: false; apparent but not genuine.
pseudobulb: a thickened bulb-like stem of sympodial orchids with one or several internodes.
pseudopinnate: term describing a lateral shoot resembling a pinnate leaf, i.e. a shoot with limited growth and with simple leaves arranged in 2 rows like the leaflets of a pinnate leaf.
pseudowhorled: of leaves, arranged in clusters on the stem, the clusters separated by regular intervals, usually produced behind a scaly bud. Fig. 2 G. cf. whorl.
puberulous (puberulent): a dense covering of very short soft hairs, minutely pubescent.
pubescent: a somewhat dense covering of short, weak, soft hairs. Fig. 14 B.
pulvinule: the pulvinus at the base of a petiolule.
pulvinus: the swelling at the base of the petiole, often capable of changing form to bring about movement of leaf, sometimes glandular or responsive to touch. A similar swelling near the apex of a petiole is referred to as an upper pulvinus. pl. pulvini.
punctate: marked with dots.
punctulate: minutely dotted.
pungent: (1) ending in a stiff, sharp point; (2) having an acrid taste or smell.
pustulate: covered with small blisters.
pyramidal: pyramid-shaped, broadest at or near the base.
pyrene: the endocarp and enclosed seed of a drupaceous fruit.
quincuncial: of the arrangement of corolla lobes in a bud, a variant of imbricate aestivation.
raceme: a simple inflorescence ending in a non-floral bud and in which the flowers are stalked, i.e. an indeterminate inflorescence. Fig. 17 H. cf. raceme-like, spike.
raceme-like: applied to a simple inflorescence ending in a floral bud in which the flowers are stalked, i.e. resembling a raceme but determinate; also used for conflorescences of similar form, particularly where there has been reduction from more complex types. cf. raceme, spike-like.
rachilla: the axis of a grass spikelet above the glumes, also the axis in sedge spikelets.
rachis: the axis of an inflorescence, pinnate leaf, or of a pinna in a bipinnate leaf.
radical (basal): of leaves, clustered at the base of the stem. Fig. 2 I. cf. cauline, rosette.
radicle: the portion of an embryo that gives rise to the primary root system of a plant.
rainforest (closed forest): a forest dominated by broad-leaved trees with dense crowns that form a continuous layer (canopy) and with one or more of the following growth forms
ramiflory: the production of flowers and fruits behind the current foliage on woody branches formed in previous, but recent, seasons. adj. ramiflorous. cf. cauliflory.
rank: (1) a vertical row; (2) leaves that are 2-ranked are in 2 vertical rows, and may be alternate or opposite.
raphe: the part of the stalk of an anatropous ovule that is fused along the side of the ovule.
raphides: needle-like crystals that occur in bundles in the vacuoles of some plant cells.
ray floret (ray flower): a zygomorphic flower in many species of the family Asteraceae, usually formed towards the periphery of the head and with the corolla extended into a strap-shaped ligule. cf. disc floret.
receptacle: the often more or less expanded top of the stalk on which a flower or flower-head arises, Fig. 12 A; an axis on which sporangia arise in ferns.
recurved: curved backwards (and hence usually downwards), e.g. of the margins of a leaf. Fig. 10 D. cf. revolute, incurved, reflexed.
reflexed: bent sharply backwards (and hence usually downwards). cf. deflexed, inflexed.
regular: see actinomorphic.
reniform: kidney-shaped. Fig. 5 G.
replum: a longitudinal partition in fruits of the family Brassicaceae, see silicula, siliqua.
resinous: with a hardened sticky surface.
resupinate: twisted through 180° as in the ovary of most orchid (family Orchidaceae) flowers.
reticulate: forming a network or reticulum; e.g. of veins, Fig. 9 H.
retinaculum: (1) a hook-like structure to which another structure is tethered, as in Orchidaceae and Asclepiadaceae (the structure to which pollen masses are attached) or in Acanthaceae (the persistent stalk of an ovule); (2) the marginal outgrowth from a spadix, as in Zosteraceae. pl. retinacula.
retrorse: directed backwards (and thus often downwards).
retuse: having the apex rounded and with a small notch. Fig. 6 H.
revolute: rolled backwards (and thus often downwards), e.g. of the margins of a leaf. Fig. 10 E. cf. recurved, involute.
rhizoid: a thread-like, unicellular absorbing structure, in fern gametophytes and some non-vascular plants.
rhizome: an underground stem, usually growing horizontally. adj. rhizomatous. Fig. 1 N.
rhombic: having the form of a 2-dimensional diamond-shaped figure. Fig. 5 H.
rhomboid: having the form of a 3-dimensional diamond-shaped solid.
riparian: of plants growing by rivers or streams.
root: part of the underground axial system of a plant which does not bear leaves and tends to grow downwards or laterally in the soil. See also adventitious, aerial root.
rootstock: a swollen region at the junction of root system and stem, mostly below ground level.
rosette: a radiating cluster of leaves, usually close to the ground at the base of a plant. Fig. 2 I. See also radical.
rostellum: in orchids, a projection of the upper edge of the stigma in front of the anthers.
rosulate: clustered into a rosette.
rotate: term applied to a shortly tubular corolla with spreading lobes or limbs.
rudimentary: imperfectly developed and non-functional.
rugose (wrinkled): covered with coarse lines or furrows. Fig. 16 G.
rugulose: with tiny wrinkles.
ruminate: (1) of a surface or tissue, with an irregular, involuted outline, as in a rumen; (2) mottled in appearance.
runcinate: term describing a pinnatifid or pinnatisect leaf with sharply incised lobes or teeth pointing towards the base. Fig. 5 Q.
runner: a slender prostrate stem having a bud at the end which sends out leaves and roots.
rush: a plant belonging to the family Juncaceae or, more loosely, to various monocotyledons.
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