Aira praecox L., Sp. Pl. 1: 65 (1753).

T: Habitat in Europae australioris campis arenosis innundatis

Vegetative form. Annual, caespitose. Leaves scattered along the culms. Culms 4-18 cm high, branched above or unbranched above, 2-3 noded. Mid-culm nodes glabrous, exposed, often slightly pigmented or not pigmented, slightly constricted or swollen. Mid-culm internodes hollow, glabrous or puberulous (minutely, usually slightly pigmented below the node), terete. Young shoots intravaginal. Leaves non-auriculate. Basal leaf sheaths not keeled, terete, glabrous or scabrous (hairs sparse but often near the margin; firmly encircling and overlapping around culm), the same colour as the lamina or purple, with the veins equally striate, with margins free, chartaceous, smooth. Ligule 2.5-4.3 mm long, not lobed, broadly decurrent, membranous, smooth, acute to obtuse, entire or erose or dentate, abaxially minutely hairy. Collar glabrous. Distinct callus at blade-sheath junction absent. Leaf blades joining the sheath abruptly, folded or supervolute, linear, 10-20 mm long, 0.4-0.6 mm wide; adaxially puberulous (sparsely), shallowly grooved; abaxially glabrous or abaxially scabrous (minutely, on the veions), with the veins equally striate (prominently); with margins scabrous (minutely), apices abruptly pointed or apices blunt and rounded, hooded. Prophyll 6.4 mm long, the keels puberulous.

Reproductive organization. Plants bisexual. Rudimentary spikelets absent. Incomplete spikelets absent.

Inflorescence. Inflorescence a panicle, pallid to green (silvery), erect, contracted, 3-8 mm wide, oblong or elliptic, symmetrical, fully exserted. Main inflorescence axis 25-120 mm long. Peduncles 15-85 mm long, usually glabrous or scabrous (scaberula sparse), finely ridged. Rachides 10-35 mm long, subterete, glabrous. Pulvini absent. Primary inflorescence branches antrorsely minutely scabrous; solitary or paired, branching at the base (2-nate) or not branched at the base, erect to narrowly spreading, filiform, distichous, without spikelets inserted at the base. Spikelets 1-2 on a typical ultimate inflorescence branch, on second order branches or on third order branches, erect, spreading.

Hermaphrodite (`perfect') spikelets. Hermaphrodite spikelets pedicellate, 3-3.8 mm long, 4.3 mm wide, laterally compressed, broadly cuneate, not disarticulating as a separate unit, disarticulating above the glumes. Pedicels 0.6-2.1 mm long (equal to less than the length of the spikelet), erect, slender (slightly distally dilated), minutely scabrous, straight. Glumes two per spikelet, similar, equal in length or subequal, about equalling the florets, equalling the proximal lemma or longer than the proximal lemma. Lower glume narrowly ovate, 3-4 mm long, 0.6-0.9 mm wide, membranous, weakly keeled or dorsally rounded, acuminate or acute, entire (occasionally splitting), muticous, obscurely margin ciliolate; 1-3 veined (the laterals short), midvein glabrous or midvein scaberulous (at apex or upper half); intercostal regions scaberulous (upper half). Upper glume narrowly ovate, 3.4-3.8 mm long, 0.6-0.9 mm wide, membranous, weakly keeled, acuminate, entire, muticous, obscurely margin ciliolate; 3 veined (the laterals short), midvein scaberulous (upper half); intercostal regions scaberulous (upper half). Rudimentary florets absent. Incomplete florets absent. Hermaphrodite florets 2 per spikelet. Rachilla disarticulating between the florets, disarticulating directly below the florets, straight, segments 0.2 mm long, glabrous, not obviously elongated between glumes or florets, not apically prolonged. Callus present, blunt, 0.1 mm long, shortly silky (hairs straight, white), hairs 0.2-0.3 mm long. Lemma similar in firmness to the glumes, laterally compressed, narrowly ovate, 2.5-3.5 mm long, 0.4-0.5 mm wide, membranous, not keeled, acuminate, bifid; awned. Lemma margins smooth (?). Lemma 5 veined (?). Lemma veins not confluent apically, obscure, scaberulous, with the hairs on all the veins, with the hairs only at the vein apex; intercostal regions scaberulous, the hairs only at the apex. Awns 1, median. Median awn much longer than the body of the lemmas, 3.4-5 mm long, 1 veined, terete, dorsal, arising from the lower half of the lemma (1/4 from base), geniculate, column twisted, scabrous. Palea fully developed, 2/3s the length of the lemma, similar in texture to the lemmas, gaping, narrowly ovate or oblanceolate, 1.8-2.3 mm long, 0.4 mm wide, hyaline to membranous, 2-keeled, keels wingless, truncate, entire or bidentate, obscurely margin ciliolate (at apex); 2 veined, veins scaberulous; intercostal regions scaberulous. Lodicules 2, free, hyaline, subulate, acute, smooth, lobed, with margin divisions lateral, glabrous. Stamens 3. Anthers 0.4 mm long, yellow, basally 2-lobed (c. 1/3). Ovary oblong, glabrous. Styles 2, apical, free to their bases.

Fruit. Fruit free from both lemma and palea (but firmly enclosed), oblong, ventrally compressed, 1.4-1.6 mm long, 0.4 mm wide, deeply furrowed, glabrous, without a fleshy apex. Hilum 0.2 mm long, elliptic, above the base. Embryo 0.4-0.5 mm long, not waisted, with an epiblast; endosperm soft.

Distribution. Introduced. Tasmania, Victoria, and Western Australia.

Ecology. Flowers Dec. Fruits Dec.-Jan.

Vouchers. Specimens examined morphologically: W.A.: Mt. Melville, Albany, 27 Nov. 1994, L.Watson (Herb. CMW). Vic.: Yarra Glen, 22 Dec, 1939, R.Black 1211.001 (CANB). Tas.: near chalet on middle slopes of Mt Barrow, growing in hollow of dead and fallen log, 9 Jan. 1949, N.T.Burbidge 2999 (CANB); Ocean Beach, Strahan, growing in sand in 4-wheel drive track, 24 Dec. 1984, P.Collier 228 (HO); 1 mi [1.6 km] E of Pinnacle, Mt Wellington, trackside in wetter sclerophyll forest, steep rocky slope, 30 Dec. 1971, UJ.H.Hemsley 6646 (HO); off Lyell Hwy at Artist Hill, stony disturbed surface, 22 Dec. 1982, A.M.Buchanan 1031 (HO).

Classification. Pooideae; Poodae; Aveneae.

Cite this publication as:
C.M. Weiller, M.J. Henwood, J. Lenz and L. Watson (1995 onwards). `Pooideae (Poaceae) in Australia - Descriptions and Illustrations'. URL http://muse.bio.cornell.edu/delta/
Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993) should also be cited.

References and Acknowledgements