Glossary of Botanical Terms

Abstract

Adapted from the glossary in Flora of Ethiopia and Eritrea, vol. 7 (1995). aristate – with an awn aristulate – diminutive of aristate auricle – an earlike lobe or appendage at the junction of leaf sheath and blade auriculate – with an auricle awn – a bristle arising from a spikelet part callus – a hard projection at the base of a floret, spikelet, or inflores-cence segment, indicating a disarticulation point caryopsis – a specialized dry fruit characteristic of grasses, in which the seed and ovary wall have become united collar – pale or purplish zone at the junction of leaf sheath and blade column – the lower twisted portion of a geniculate awn, or the part be-low the awn branching-point in Aristideae compound – referring to inflorescences made up of a number of small constituent inflorescences (as in some Andropogoneae), or a raceme with some secondary branching culm – the flowering stem of a grass plant culm sheath (bamboos) – modified, often non-photosynthetic, culm leaf with an expanded sheath and much reduced blade, usually deciduous as the culm matures diffuse (bamboos) – culms arising singly from long slender rhizomes. extravaginal – branching in which the young shoot breaks through the base of the leaf sheath floret – the individual unit of a spikelet, comprising a lemma and palea with enclosed reproductive organs glume – one of a pair of empty scales at the base of a grass spikelet heterogamous spikelets – the paired spikelets found in most Andro-pogoneae, where one spikelet of the pair is sessile and produces a caryopsis, and the other spikelet is pedicelled, of different form, and staminate or sterile hilum – the scar on the caryopsis marking the site of the attachment of the pericarp and testa, found on the opposite side from the embryo homogamous spikelets – in Andropogoneae the paired spikelets some-times present at the base of the raceme, of similar appearance and not producing any caryopses, often resembling the pedicelled spikelets or assuming a protective involucral function intravaginal – branching in which the young shoot grows up inside the leaf sheath, emerging at the sheath mouth iterauctant (bamboos) – inflorescence with pseudospikelets with glumes subtending axillary buds capable of partial or extensive spikelet rami-fication leaf blade – the distal expanded part of a grass leaf leaf sheath – the basal part of the grass leaf which normally encloses a culm internode lemma – the lower of the two bracts enclosing the grass flower and together with the palea comprising a floret leptomorph (bamboos) – rhizome monopodial, elongated, more slender than culms ligule – a membrane or line of hairs on the inner (adaxial) side of the junction of the leaf sheath and leaf blade; bamboos sometimes have an external ligule on the abaxial side of the junction lodicule – a small scale-like or fleshy structure at the base of the sta-mens in a grass floret, usually 2 in each floret (often 3 or more in bamboos); they swell at anthesis, causing the floret to gape open oral setae – marginal setae inserted at junction of leaf sheath and blade, on the auricles when these are present pachymorph (bamboos) – rhizome sympodial, thicker than culms palea – the upper and inner scale of the grass floret which encloses the grass flower, usually 2-keeled panicle – in grasses, an inflorescence in which the primary axis bears branched secondary axes with pedicellate spikelets pedicel – in grasses, the stalk of a single spikelet within an inflo-rescence peduncle – the stalk of a raceme or cluster of spikelets pluricaespitose (bamboos) – culms arising in a series of clusters along a long slender rhizome prophyll – in grasses, a 2-keeled, hyaline, modified leaf, placed within a leaf sheath on the adaxial side of a branch pseudopetiole – the narrow basal portion of some leaf blades, resem-bling a petiole pseudospikelet (bamboos) – spikelet in which the outer glumes or bracts subtend axillary buds which can develop to form lateral spike-lets or branches raceme – in grasses, an unbranched axis bearing spikelets; racemes may be solitary, digitate, or scattered raceme base – short stalk beneath the individual racemes of a pair in some Andropogoneae raceme pair – pairs of racemes supported by spatheoles in the com-pound panicles of some Andropogoneae rachilla – the central axis of the spikelet which bears the florets rachilla extension – a prolongation of the rachilla beyond the upper-most (or single) floret rachis – the axis of a raceme secondary spathe – spathe supporting a second tier of branching within the compound panicle of some Andropogoneae semelauctant (bamboos) – inflorescence with glumes not subtending viable buds or branches sinus – the space between two projecting lobes or teeth spathate – with spathes spathe – a bract or modified bladeless leaf subtending the inflorescence or part of it spatheole – the uppermost spathe supporting the racemes within the compound inflorescence of some Andropogoneae spikelet – the basic unit of a grass inflorescence; usually composed of two glumes and one or more florets on a rachilla spikelet pair – the arrangement of one sessile and one pedicelled spike-let arising from the same node characteristic of the Andropogoneae tiller – a leafy non-flowering shoot triad – a group of three spikelets borne together unicaespitose (bamboos) – culms all arising in a single clump from pachymorph rhizomes