Avena sibirica Linnaeus, Sp. Pl. 1: 79. 1753; Achnatherum avenoides (Honda) Y. L. Chang; A. confusum (Litvinov) Tzvelev; A. sibiricum var. qinghaiense Y. J. Wang; Stipa avenoides Honda; S. confusa Litvinov; S. sibirica (Linnaeus) Lamarck.

Perennial, loosely tufted, scaly buds at base. Culms erect, 60–150 cm tall, 1.7–3 mm in diam., smooth, 3–4-noded. Leaf sheaths smooth, lower longer than internodes; leaf blades usually convolute, occasionally flat, 20–60 cm, 3–7 mm wide, abaxial surface smooth, adaxial surface scaberulous, sometimes also pilose, apex finely acuminate; ligule truncate, 0.5–2 mm. Panicle contracted, often dense, 10–30(–60); branches 3 to several per node, suberect or narrowly ascending, with spikelets to base. Spikelets 7–10 mm, yellowish green or purple; glumes subequal, elliptic-oblong, 3-veined, smooth or scaberulous, often scabrid-spinulose on midvein, apex acute or denticulate; callus acute, 0.5–1 mm; lemma narrowly lanceolate, leathery, 5–8 mm, densely pilose, hairs slightly longer upward, 1–2 mm at awn base, margins overlapping and enclosing palea, apex entire; awn persistent, 1.5–2.5 cm, 1(or 2)-geniculate, column twisted, minutely hispidulous, bristle scabrid. Anthers ca. 4 mm, bearded at apex. Fl. and fr. Jul–Sep.

Achnatherum sibiricum, A. brandisii, A. pekinense, A pubicalyx, and probably A. nakaii form a complex of rather ill-defined, intergrading species. The complex lies on the boundary between Stipa and Achnatherum. The leathery, convolute lemma enclosing the palea and almost entire lemma apex are typical of Stipa, whereas the short glumes scarcely exceeding the floret, non-pungent callus, and persistent awn are characters of Achnatherum. The poisonous properties reported for some members of this complex are due to the presence of cyanogenic glycosides.

Besides the key characters, typical Achnatherum sibiricum is distinguished from A. pekinense by the entire lemma apex and the slightly longer lemma hairs around the base of the awn. Achnatherum sibiricum var. qinghaiense is said to be distinguished by obtuse glumes and an obtuse callus. The type has not been seen.

Grassy mountain slopes, forest fringes, roadsides; 600–3400 m. Heilongjiang, Henan, Nei Mongol, Ningxia, Qinghai, Sichuan, Xinjiang, Xizang, Yunnan [Kazakhstan, Kyrgyzstan, Mongolia, Russia, Uzbekistan; SW Asia (Caucasus)].