Avena sativa L., Sp. Pl. 79 (1753).

A. fatua var. sativa (L.) Hausskn., ; A. fatua subsp. sativa (L.) Thell.,

Vegetative form. Annual, caespitose. Leaves scattered along the culms. Culms 25-125(-180) cm high, branched above or unbranched above, 2-5 noded. Mid-culm nodes glabrous, exposed or hidden by the leaf sheaths (but usually hidden, the sheath longer than the internode), not pigmented, constricted. Mid-culm internodes hollow, glabrous, terete. Young shoots intravaginal (?). Leaves non-auriculate. Basal leaf sheaths not keeled, terete, glabrous, with the veins equally striate, with margins free, membranous, smooth. Ligule 1.5-3(-8) mm long, not lobed, decurrent, membranous to chartaceous, smooth, obtuse or truncate, entire or erose, abaxially usually glabrous or hairy (minutely). Collar glabrous. Distinct callus at blade-sheath junction absent. Leaf blades joining the sheath gradually, flat, linear, 80-450 mm long, 3-14(-25) mm wide; adaxially glabrous or adaxially scabrous, not grooved; abaxially glabrous or abaxially scabrous, with midrib prominent or with the veins equally striate; with margins smooth or with margins scabrous, apices acuminose; convolute in bud.

Reproductive organization. Plants bisexual. Rudimentary spikelets absent. Incomplete spikelets absent. Inflorescence of cleistogamous spikelets (?).

Inflorescence. Inflorescence a panicle, pallid to green, nodding, open, c. one-sided, fully exserted. Main inflorescence axis 210-815 mm long. Peduncles 150-485 mm long, glabrous (occasionally glaucous), slightly ridged. Rachides 60-330 mm long, terete, glabrous (occasionally glaucous). Pulvini present. Primary inflorescence branches scabrous; solitary or paired or clustered, branching at the base, spreading, distichous. Spikelets 1-2 on a typical ultimate inflorescence branch, on first order branches or on second order branches, pendulous, reflexed (?).

Hermaphrodite (`perfect') spikelets. Hermaphrodite spikelets pedicellate, 18-32 mm long, to 20 mm wide, laterally compressed, cuneate, not disarticulating as a separate unit, disarticulating above the glumes. Pedicels 7-35 mm long, recurved, slender (distally dilated), antrorsely scabrous, straight. Glumes two per spikelet, similar, subequal, exceeding the florets, longer than the proximal lemma. Lower glume narrowly ovate, (15-)20-28 mm long, 2.5-4 mm wide, membranous to chartaceous, dorsally rounded, acute or subulate, entire, muticous, margin smooth; (7-)8-11 veined, veins prominent, midvein glabrous; intercostal regions glabrous. Upper glume narrowly ovate, 25-32 mm long, 2.5-4 mm wide, membranous to chartaceous, dorsally rounded, acute or subulate, entire, muticous, margin smooth; (7-)10-12 veined, veins prominent (cross-veins conspicupous), midvein glabrous; intercostal regions glabrous. Rudimentary florets distal to the hermaphrodite florets. Incomplete florets absent. Hermaphrodite florets (1-)2-3 per spikelet. Rachilla not disarticulating between the florets, straight, segments 1-1.3 mm long, glabrous, shortly elongated between the upper glume and first floret and elongated between all florets, apically prolonged; prolongation 0.4-2 mm long, terminated by a rudimentary floret. Callus present, glabrous or silky (few hairs only, straight, c. stiff but not harsh to touch), hairs to 2.3 mm long. Lemma decidedly firmer than the glumes, laterally compressed, narrowly elliptic, 17-23 mm long, 3-3.5 mm wide, coriaceous, not keeled, acute, bidentate, muticous and awned (upper florets unawned). Lemma margins membranous; smooth or ciliolate (obscurely, at the apex). Lemma 7 veined. Lemma veins not confluent apically, prominent, the laterals raised and the marginals raised (only at the apex), connected by obscure transverse veins, scaberulous, with the hairs on all the veins, with the hairs only at the vein apex; intercostal regions glabrous. Awns 1, median. Median awn much longer than the body of the lemmas (c. twice the lemma length), 15-40 mm long, 1 veined, terete, dorsal; 7.6-10.2 mm below tip; arising from the mid-point of the lemma (or slightly above), geniculate, usually column twisted (and stout, golden-brown) or column not twisted (and slender), scabrous. Palea fully developed, slightly shorter than the lemmas, thinner than the lemmas, narrowly elliptic, 14-16.5 mm long, 3-3.8 mm wide, cartilaginous (lateral faces membranous), 2-keeled, keels wingless, acute, shortly bidentate, margin smooth; 2 veined, veins ciliate (hairs prominent in upper 2/3s, to 0.4 mm long); intercostal regions glabrous. Lodicules 2, free, hyaline, triangular, acute, smooth, with entire margins, glabrous. Stamens 3. Anthers yellow, entire or shortly basally 2-lobed (1/9-1/11 the length). Cleistogamous anthers 3.8-4.7 mm long. Ovary obovoid, pilose (or silky, antrorse, to 1.8 mm long, pale golden, not rough to touch), with the hairs over the entire ovary. Styles 2, apical, free to their bases (widely separated).

Fruit. Fruit free from both lemma and palea, golden, oblong, ventrally compressed, 9.4-12 mm long, 1.8-3.5 mm wide, longitudinally grooved, pilose, with dense hairs (particularly at apex), the hairs covering most of the body, with a fleshy apex (surface readily removed). Hilum 7-8 mm long (?), linear (?, most of the length of the caryopsis). Embryo 3.4-4.3 mm long, not waisted, with an epiblast; endosperm hard.

Common name. Oats.

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

Ecology. Mesophytic.

Vouchers. Specimens examined morphologically: S.A.: Grown Waite Institute from seed from Hannafords grader near Naracoorte, 24 Oct. 1969, D.E.Symon (AD, CANB). N.S.W.: 6 mi N. of Guyra, crop plant in paddock, 9 Feb. 1955, M.Gray CSIRO 3149 ?? (CANB); c. 3 mi [4.8 km] E of Cooma along the Nimmitabel Rd, roadside weed copmmunity in open grass plain, erect grass with drooping spikelets, 20 Nov. 1963, R.Pullen 3949 (CANB). A.C.T.: Civic Centre, Canberra, 12 Oct. 1931, T.B.Paltridge (CANB); Turner, Canberra, residential garden, 20 Nov. 1968, R.Pullen 4304 (CANB); Acton, 5 Oct. 1936, R.M. (CANB).

Notes. Economic importance: widely cultivated in temperate regions as a cereal crop or for forage.

Classification. Pooideae; Poodae; Aveneae.

References. Morphology: S.W.L.Jacobs & S.M. Hastings; Morris 62 (1991).

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