异燕麦 yi yan mai

Perennial, rhizomes very short or absent, forming mats. Culms tufted, erect, 20–70 cm tall, usually 2-noded. Leaf sheaths of cauline leaves closed for less than 1/4 of length; leaf blades flat or folded, 10–25 cm, 2–5 mm wide, smooth or scabrid, margins thick, white, base straight, apex subacute; ligule lanceolate, 3–6 mm. Panicle contracted, sometimes dense, 4–15 cm; branches usually paired, erect or ascending, scabrid, bearing 1–4 spikelets. Spikelets 1.1–1.7 cm, green or brown, florets 3–6; rachilla hairs 1–2 mm; glumes membranous, 3(–5)-veined, lower glume 9–12 mm, upper glume 10–13 mm; lemmas leathery, hyaline above awn insertion, lowest 10–13 mm, asperulous, apex 2-toothed; awn 1.2–1.5 cm, geniculate, column twisted, flat; palea keels minutely ciliolate. Anthers ca. 4 mm. Fl. and fr. Jun–Sep.

Hill slopes in steppe, forest margins, moist meadows in high mountains; 100–3500 m. Gansu, Hebei, Heilongjiang, Henan, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, Xinjiang, Yunnan [Kazakhstan, Kyrgyzstan, Mongolia, Russia; North America].

This is a variable species with higher-altitude forms distinguishable at subspecific rank. These forms correspond to plants from uplands in W North America, from where the species was first described.