1. Avena sativa Linnaeus, Sp. Pl. 1: 79. 1753.
燕麦 yan mai
Annual. Culms solitary or tufted, erect, 40–180 cm tall, unbranched. Leaf sheaths usually glabrous; leaf blades 15–30 cm, 4–10 mm wide, glabrous, margins sometimes scaberulous; ligule 3–6 mm. Panicle loose and open or contracted, 20–40 cm, nodding; branches spreading or contracted. Spikelets 2–3 cm, florets 2(or 3); rachilla ± glabrous, straight, not disarticulating or fracturing irregularly at maturity, florets lacking a basal bearded callus, internodes short, less than 0.5 mm; glumes lanceolate, subequal, as long as spikelet, 7–9-veined; lemmas 1.2–2.5 cm, leathery in lower half, herbaceous and distinctly veined above, glabrous or nearly so, apex minutely and irregularly 2–4-denticulate; awn 2.5–3.5 cm, weakly geniculate or rudimentary or absent. Grain adherent to lemma and palea at maturity. 2n = 42.
Widely cultivated in China [of cultivated origin].
This species is cultivated as a cereal crop (oats) in north-temperate regions of the world, and also as a green fodder crop. Genetic evidence points to Avena sterilis as the wild ancestor of A. sativa, and A. fatua as a weedy derivative. Hybrids between A. sativa and A. fatua with hairy florets or well-developed awns may occur where the two species grow together.