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Clausospicula

Clausospicula Aust. Syst. Bot. 4: 399 (1991).

Derivation:. From Latin clausum (enclosed space) spica (thorn) and ula (diminutive), alluding to the small spikelets.

Taxonomic revisions, nomenclatural references:. M.Lazarides, J.Lenz and L.Watson, Austr. Syst. Bot. 4: 391–405 (1991).

Key references (keys and floras):. B.K.Simon, Key to Australian Grasses 86 (1993); D.Sharp and B.K.Simon, AusGrass (2002).

Native, endemic. 1 species. NT.

Habit. Annual, single-stemmed. Ligule an unfringed membrane.

Inflorescence. Inflorescence paniculate, a compound pseudo-inflorescence (each ‘raceme’ reduced to one ‘triplet’, clasped basally by the peculiar, trumpet-shaped tip of the peduncle). Spikelet-bearing joints with only one spikelet-bearing joint, axes with heteromorphic spikelets, axes solitary, axes disarticulating at joints (i.e. each at its only joint). Internodes disarticulating obliquely.

Spikelets. Spikelets subterete to dorsally compressed, in triplets (one of the pedicellate members sometimes missing), sessile and pedicelled, in pedicelled/sessile combinations; with rachilla terminating in a floret; sessile spikelet with lower incomplete floret. Fertile spikelets subterete to dorsally compressed, falling with glumes.

Glumes. Glumes more or less equal, about equal to spikelet or exceeding florets, long relative to adjacent lemmas (more or less exceeding the lower lemma), hairy and hairless (usually tubercled basally and towards the tip, otherwise glabrous), awned, non-keeled, dissimilar (both becoming indurated, the lower abruptly contracted above and with or without a short bristle from the narrow, truncate to notched apex, the upper attenuate into a long, slender scabrous awn 14–19 mm long which is often twisted around the lemma awn). Lower glume convex on back, relatively smooth and tuberculate, 4 nerved (without a median). Upper glume 3 nerved.

Florets. Lower incomplete floret(s) sterile. Lemmas awnless, 2 nerved or 4 nerved, more or less equalling fertile lemmas to exceeding fertile lemmas, similar in texture to fertile lemmas (hyaline), not becoming indurated. Fertile florets 1. Lemmas less firm than glumes, entire at apex (the hyaline margins of the stipe antero-laterally decurrent on the base of the awn, with no indication of lobes), awned, without a germination flap, 3 nerved, with nerves non-confluent, not keeled. Awns 1, apical, geniculate, hairless to hairy, much longer than body of lemma (8–11 cm long). Awn bases twisted, not flattened. Palea conspicuous and relatively short, entire to apically notched, textured like lemma (hyaline), several nerved or 1 nerved. Callus pointed. Lodicules 2. Stamens 3 (short). Stigmas 2, or 3. Grain medium sized (about 5.6 mm long), ellipsoid, compressed laterally (above) or compressed dorsiventrally to terete (below), glabrous. Hilum short. Embryo large. Pedicels free of rachis.

Kranz Anatomy. C4.

Habitat. Mesophytic.

Classification. Panicoideae; Andropogoneae.

Notes. The diagnostic characters of Clausospicula include cleistogamous spikelets, reduced panicles, racemes and spikelets, and pedicelled spikelets which are poorly developed and deciduous, or suppressed. Also the glumes of the bisexual spikelet are awned and slightly keeled or without keels. A prominent feature is the extension of the peduncle into an appendage to which the callus of the bisexual spikelet is attached (Lazarides, Lenz and Watson, 1991).

Types Species. C. extensa Lazarides.

Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith