Derivation
Avena L., Sp. Pl. 79 (1753); from the Latin avena (nourishment) and name for the oat, A. sativa.

byzantina- from Byzantium, now Istanbul, Turkey.

Published in
Linnaea 21: 392 (1848).

Habit
Annual. Culms erect or geniculately ascending, 50–150 cm tall. Mid-culm nodes glabrous. Lateral branches simple. Leaves mostly basal. Ligule an eciliate membrane, 3–7 mm long. Leaf-blades 15–30 cm long, 2–9(–15) mm wide. Leaf-blade surface glabrous. Leaf-blade margins scabrous. Leaf-blade apex abruptly acute, hooded.

Inflorescence
Inflorescence compound, a panicle. Panicle open, elliptic, 10.5–25 cm long.

Spikelets
Spikelets pendulous, solitary. Pedicels filiform. Fertile spikelets many flowered, comprising 2–4 fertile florets, with a barren rhachilla extension, lanceolate, laterally compressed, 25–30(–35) mm long, breaking up at maturity. Spikelets disarticulating above glumes but not between florets. Floret callus evident, bearded, obtuse, fracturing irregularly, with elliptic scar, hairs 3–5.5 mm long.

Glumes
Glumes persistent, similar, thinner than fertile lemma, gaping. Lower glume lanceolate, 23–30 mm long, equalling upper glume, membranous, (7–)9-nerved. Lower glume apex acuminate. Upper glume elliptic, 25–33 mm long, 150–180% of length of adjacent fertile lemma, membranous, (7–)9–11-nerved, midnerve eciliate. Upper glume apex acuminate.

Florets
Fertile lemma lanceolate, 15–20 mm long, coriaceous, much thinner above, 7-nerved. Lemma apex entire or dentate, 2-fid, with lobes 1.5 mm long, obtuse, 1-awned. Median (principal) awn dorsal, arising 50% way up back of lemma, straight or curved, 25–35 mm long overall, without a column. Palea 12–15 mm long. Palea keels wingless, ciliolate. Palea apex lobed, 2-fid. Anthers 3. Ovary pubescent all over. Grain with adherent pericarp, grooved, hairy all over. Hilum linear.

Continental Distribution:
Europe, Africa, Temperate Asia, Tropical Asia, Australasia, South America.

Australian Distribution:
Western Australia: Roe.

Classification. (GPWG 2001):
Pooideae: Aveneae

Notes
Introduced. Also recorded from Qld., N.S.W. and A.C.T., but not recorded as naturalised. Flowers Oct.–Nov. Fruits Oct.–Nov.