4. Avena sterilis Linnaeus subsp. ludoviciana (Durieu) Nyman, Consp. Fl. Eur. 810. 1882.
长颖燕麦 chang ying yan mai
Avena ludoviciana Durieu, Actes Soc. Linn. Bordeaux 20: 41. 1855.
Annual. Culms solitary or tufted, erect or ascending, 50–120 cm tall, unbranched, 2–4-noded. Leaf sheaths glabrous or basal sheaths puberulous; leaf blades up to 60 cm, 4–13 mm wide, scaberulous, glabrous; ligule 3–4 mm. Panicle loose, open, pyramidal, 13–30 cm, nodding; branches coarsely scabrid. Spikelets 2–3 cm, florets 2 or 3, 2-awned; rachilla disarticulating only below lowest floret, florets falling together at maturity, only lowest floret with a bearded callus, internodes glabrous; glumes narrowly elliptic-oblong, subequal, as long as spikelet, 7–9-veined, apex finely acuminate; callus hairs up to 5 mm; lemmas 1.8–2.5 cm, leathery, hispid, finally brown in lower half, green and scabrid above, awned at about lower 1/3, apex finely 2-fid; awn 3–6 cm, fairly slender, strongly geniculate, column dark brown, pubescent. 2n = 42.
Arable weed, adventive. Yunnan [native to SW Asia and Europe].
This is a noxious weed of arable land, especially fields of cereals, native to the Mediterranean region and SW Asia, but now widespread in warm-temperate regions of the world. It has been recorded in China only from Yunnan.
The typical subspecies, Avena sterilis subsp. sterilis, is distinguished by its larger, 3–5 cm spikelets with 3–5 florets, 9–11-veined glumes, and stouter, 6–9 cm awns. Both subspecies occur over the whole range of the species.