Aira cupaniana Guss., Fl. Sicul. Syn. 1: 148 (1843).

Illustrated in: Jessop & Toelken (eds.), Fl. S. Australia 4: 1906 (1986).

Vegetative form. Annual, slender, usually erect or geniculate, culms solitary or caespitose. Leaves scattered along the culms. Culms 6-40 cm high, unbranched above, 3-4 noded. Mid-culm nodes glabrous, exposed (but sheath shorter or longer than culm internode), not pigmented, constricted. Mid-culm internodes hollow, glabrous, terete. Young shoots intravaginal. Leaves non-auriculate. Basal leaf sheaths not keeled, terete, minutely, retrorsely scabrous (on the veins), the same colour as the lamina or purple, with the veins equally striate, with margins free, hyaline, smooth. Ligule 3.8-6.2 mm long, not lobed, decurrent, hyaline, smooth, acute, entire, abaxially hairy (sparsely scabrous). Collar minutely scabrous. Distinct callus at blade-sheath junction absent. Leaf blades joining the sheath gradually, folded or involute, linear, 15-95 mm long, 0.3-0.6 mm wide; adaxially puberulous, shallowly grooved; abaxially scabrous (hairs antrorse, on the veins), with the veins equally striate; minutely with margins scabrous, apices abruptly pointed or apices blunt and rounded, hooded. Prophyll 8-15 mm long, glabrous or scabrous (sparsely).

Reproductive organization. Plants bisexual. Rudimentary spikelets at the base of the inflorescence (on lower panicle branches), or absent. Incomplete spikelets absent. Hermaphrodite florets protandrous. Inflorescence of cleistogamous spikelets. Cleistogamous spikelets on the exserted inflorescence.

Inflorescence. Inflorescence a panicle, pallid to silvery, erect, open, symmetrical, fully exserted. Main inflorescence axis 50-240 mm long. Peduncles 23-150 mm long, glabrous, slightly ridged. Rachides 20-95 mm long, subterete, glabrous. Rachis angles glabrous. Pulvini present. Primary inflorescence branches scabrous; paired, not branched at the base, spreading, filiform, distichous, without spikelets inserted at the base. Spikelets 1 on a typical ultimate inflorescence branch or 2 on a typical ultimate inflorescence branch, on second order branches or on third order branches or on fourth order branches, erect, spreading.

Hermaphrodite (`perfect') spikelets. Hermaphrodite spikelets pedicellate, 2.1-2.6 mm long, 0.9-1.1 mm wide, laterally compressed, oblong, not disarticulating as a separate unit, disarticulating above the glumes. Pedicels 2.8-6.5 mm long (1-3 times the length of the spikelet), erect, slender (abruptly dilated (swollen) at apex), scabrous, straight or sinuous. Glumes two per spikelet, similar, subequal, exceeding the florets, longer than the proximal lemma. Lower glume slightly longer than the upper glume, narrowly ovate, 2.1-2.5 mm long, 0.3-0.45 mm wide, membranous, weakly keeled, acute to obtuse (hyaline), entire, muticous, margin smooth or margin scabrous; 1 veined, midvein scaberulous (upper half); intercostal regions glabrous. Upper glume narrowly ovate, 2-2.3 mm long, 0.3-0.4 mm wide, hyaline to membranous, weakly keeled, acute to obtuse (hyaline), entire, muticous, margin smooth or margin scabrous; 1 veined, midvein scaberulous (upper half); intercostal regions glabrous. Rudimentary florets absent. Incomplete florets absent. Hermaphrodite florets 2 per spikelet (dissimilar). Rachilla disarticulating between the florets, disarticulating directly below the florets, straight, segments 0.08-0.1 mm long, glabrous, shortly elongated between the upper glume and first floret and elongated between all florets, apically prolonged; prolongation 0.05 mm long, naked. Callus present, blunt, 0.05 mm long, of lower lemma glabrous or silky (the hairs short, straight, silky, white, always on L2), hairs to 0.2 mm long. Lemma similar in firmness to the glumes (lower lemma 1/2-2/3s the glume length, upper lemma 2/3-3/4), laterally compressed, narrowly ovate, 1.25-1.4 mm long (upper floret 1.6-1.9), 0.4 mm wide (upper floret 0.25-0.3), membranous, not keeled, acute (in upper floret long and tapering to 2 short setae), entire (upper floret bifid); lower lemma muticous and awned (upper lemma). Lemma margins smooth or scabrous (near apex). Lemma 5 veined (laterals short). Lemma veins not confluent apically, obscure, scaberulous, with the hairs on the midvein, with the hairs only at the vein apex; intercostal regions scaberulous, the hairs only at the apex (particularly, c. papillose elsewhere). Awns of upper floret 1 (well exserted), median. Median awn much longer than the body of the lemmas, 2.5-3 mm long, 1 veined, terete (sub-), dorsal, arising from the lower half of the lemma (1/4 lemma length from base), geniculate, column twisted, scabrous. Palea fully developed, of lower lemma slightly shorter than the lemmas (1/2-3/4 in upper lemma), slightly thinner than the lemmas, narrowly ovate, 1.05-1.15 mm long, 0.2-0.3 mm wide, hyaline to membranous, 2-keeled, keels wingless, acute to obtuse, shortly bidentate, margin smooth; 2 veined, veins glabrous; intercostal regions papillose. Lodicules 2, free, hyaline, oblong, acute, smooth, with entire margins, glabrous. Stamens 3. Anthers yellow or purple, basally 2-lobed (c. 1/3 anther length). Cleistogamous anthers 0.45-0.53 mm long. Ovary oblong or elliptic, glabrous. Styles 2, apical, free to their bases.

Fruit. Fruit slightly adhering to lemma, elliptical, ventrally compressed, c. 1 mm long, c. 0.3-0.4 mm wide, shallowly longitudinally grooved, glabrous, without a fleshy apex. Embryo 0.2 mm long, not waisted, with an epiblast; endosperm hard.

Cytology. 2n = 14 (European).

Common name. Silvery Hairgrass.

Distribution. Introduced. New South Wales, Australian Capital Territory, Victoria, Western Australia, Queensland, and South Australia. World distribution: Mediterranean.

Ecology. Mesophytic; in open habitats. In disturbed areas or open woodland. Flowers Oct.-March.

Vouchers. Specimens examined morphologically: N.S.W.: 2 mi [3.2 km] NE of Ulan, up to 9", locally abundant in predominantly cleared land, 10 Oct. 1959, R.Story 6819 (CANB, NSW). A.C.T.: O'Connor, disturbed woodland, 13 Nov. 1960, H.S.McKee 7584 (CANB).

Notes. Economic importance: none.

Classification. Pooideae; Poodae; Aveneae.

References. Morphology: Jacobs & Hastings, Fl. New South Wales ms. 172 (1992). Cytology: Tutin et al. (1980) p. 227. Illustrations: aira01.gif

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