Glossary of Terms N – Z

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| A- L | N – Z |

Midrib: the central leaf vein which runs from the base to the apex. (Also applied to leaf-like structures.)

Naturalised: a species in a new locality (spread beyond its perceived original distribution), which produces new generations in the new locality without direct human intervention.

Node: the portion (‘joint’) of a stem from which a leaf arises.

Nut: a one-seeded, hard, bony fruit.

Oblanceolate: a shape (usually referring to leaves) which is tapered to a point at both ends but broadens towards the apex.

Oblong: an (approximately) right-angled, 4-sided shape; longer than broad with opposite sides (roughly) parallel; often rounded near the ends.

Obovate: a roughly elliptical shape with the terminal half broader than the basal.

Organ: a visibly differentiated part of a plant which performs specific functions.

Outbreeding: mating of not closely related individuals (opp. inbreeding).

Ovary: the basal part of the female organ (carpel(s)) of a plant in which seeds develop.

Ovate: an oval shape (like a longitudinal section through an egg shape; broader at the base than the apex).

Ovoid: egg-shaped (applied to 3-dimensional forms).

Oxalate: salt of oxalic acid (H2C201); common in plants. Soluble oxalates can be toxic to humans and animals.

Palea: the upper (inner) bract (with the lower, inner lemma) enclosing other floral parts of grasses.

Palmate: lobed, divided or ribbed like the palm of a hand.

Panicle: a branched inflorescence which is composed of racemes.

Pappus: a tuft of hairs or bristles; often on the ‘seeds’ (achenes) of plants in the Asteraceae family.

Parasite: an organism living in or deriving nourishment from another organism (adj. parasitic).

Pedicel: a stalk of a single flower, or grass spikelet (adj. pedicellate).

Peduncle: a stalk of an inflorescence or solitary flower (adj. pedunculate).

Pendulous: drooping, hanging downward.

Perennial: living for more than two years.

Perianth: the calyx (sepals) and corolla (petals) collectively, especially when appearing similar or combined in one structure.

Petal: one unit of the inner bracts (corolla) in a flower; often showy.

Petiole: the stalk of a leaf (adj. petiolate).

Petiolule: the stalk of a leaflet in a compound leaf.

Photosensitisation: sensitivity of lightly pigmented skin to sunlight. Can be induced in animals by consumption of certain plant species.

Pinnate: the arrangement of leaflets (in a compound leaf) on opposite sides of a common axis (rhachis).

Pinnatisect: cut into lobes on both sides of the midrib to or almost to the midrib (referring to leaf laminas).

Pistil: the female organs of a flower which may be a single carpel or group of carpels (adj. pistillate).

Propagation: multiplication from parent stock.

Prostrate: lying along the ground.

Pyrrolizidine: a molecule with a joined double ring structure which contains one nitrogen and seven carbon atoms.

Raceme: an inflorescence of flowers on pedicels whose growing point continues to add to the inflorescence so that the youngest flowers are nearest the apex.

Ray: (floret) outer strap-like (‘petals’) which occur in outer whorls of flower heads of the Asteraceae – also used for the branches of an (umbel) inflorescence in the Apiaceae.

Reflexed: turned abruptly backwards or downwards.

Rhachilla: the axis within the spikelet of a grass or sedge.

Rhachis: the axis or axes of a compound leaf or in. florescence.

Rhizome: an underground stem (usually horizontal) (adj. rhizomatous).

Rosette: a cluster of leaves radiating from a central crown, usually close to the ground.

Sepal: one of the (usually green) segments in the outer whorl (of 2) of the leaf-like structures of a flower (the inner segments are the petals).

Sessile: without a petiole, peduncle, pedicel or stalk, (i.e. directly attached -‘sitting’).

Sheath: (usually referring to leaves) a long, tubular stem-clasping part.

Shoot: a stem and its leaves.

Simple: (usually referring to leaves) not divided (into leaflets).

Species: a taxonomic unit which is the largest group capable of interbreeding to produce fertile offspring.

Spike: an inflorescence in the form of a raceme with sessile flowers on a simple elongated axis. The flowers may be congested or distant.

Spikelet: a small spike; the unit of a grass inflorescence usually composed of one or more florets sub tended by 2 glumes.

Spine: a hard sharp-pointed structure.

Spore: a (usually microscopic) unit of dispersal in the ferns (Pteridophytes); (in this sense equivalent to seeds in flowering plants).

Stalk: (loosely) any support organ (e.g. stem, petiole, peduncle).

Stamen: the male organ of a flower which produces pollen and usually consists of an anther and a filament (adj. staminate).

Stem: the main axis (or axes) of a plant usually bearing leaves.

Stigma: part of the female organ of a flower adapted for reception and germination of pollen.

Stolon: a horizontal stem which may take root at the nodes (adj. stoloniferous).

Style: the (usually elongated) part of the female organ (carpel(s)) of a plant; situated above the ovary and bearing the stigma.

Subspecies: a taxonomic subdivision within a species; usually geographically isolated variants.

Taxonomy: the science of the classification of organisms.

Tendril: a slender elongated thread-like organ which may cling to objects for support.

Terminal: borne at the end of (a stem etc.) (adj. terminally).

Tiller: the shoot of a grass; usually arising basally and laterally and growing erect.

Trifoliate: (strictly trifoliolate). Having three leaflets (as in clover leaves).

Truncate: terminating abruptly as if cut off.

Tuber: a swollen part (usually of an underground stem (rhizome) as in potato) (adj. tuberous).

Tubercle: a small swelling (adj. tuberculate).

Umbel: an inflorescence in which all the pedicels arise at the tip of a peduncle and the flowers lie in approximately the same horizontal plane (adj. urnbelliferous).

Valve: distinct portions into which some organs break (e.g. fruits in Brassicaceae). – also used for inner perianth segments in the Polygonaceae.

Variegated: marked with irregular patches of (usually) lighter colour; especially light patches on green leaves.

Variety: a taxonomic subdivision within a species which differs as a group in minor definable characteristics from the rest of the species, and is named according to the rules of botanical nomenclature (cf. cultivar-a variety produced artificially or selected by humans which is given a vernacular name).

Vein: discrete vascular tissue (bundles), especially in reference to leaves.

Weed: any plant growing where it is not wanted.

Whorl: a ring of three or more similar appendages.