天山异燕麦 tian shan yi yan mai

Avenastrum tianschanicum Roshevitz, Izv. Bot. Sada Akad. Nauk SSSR 30: 773. 1932.

Perennial, densely tufted. Culms erect, 14–50 cm tall, glabrous below panicle. Leaf sheaths usually densely pubescent; leaf blades filiform, 1/8–1/2 length of culms, 1.5–3 mm wide, scabrid on adaxial surface; ligule of basal leaves 2–3 mm, of culm leaves less than 1 mm. Panicle contracted, oblong in outline, 4–8 cm; branches suberect, short, puberulous, with few spikelets. Spikelets 0.9–1.1 cm, yellowish brown variegated violet, florets 2–3; rachilla bearded; lower glume 8–10 mm, 1–3-veined, upper glume 9–11 mm, 3–5-veined; lowest lemma 7–8 mm, 5–7-veined, apex denticulate; awn ca. 1.5 cm, genicu-late, column twisted, terete; palea keels ciliolate. Anthers ca. 3 mm. Fl. and fr. Jul–Sep.

Shady places on mountain slopes, forests; 1400–2700 m. Xinjiang (Tian Shan) [Kazakhstan (Tian Shan), Tajikistan (Pamirs)].

Several species of Helictotrichon, including H. tianschanicum and H. mongolicum, have been described by Russian authors from the mountain ranges bordering Xinjiang and Mongolia. The described differences between them are very slight and may perhaps refer to geographic races rather than species. It has not been possible to study variation nor to verify their identity.

Helictotrichon altaicum Tzvelev (H. desertorum subsp. altaicum (Tzvelev) Holub), described from Mongolia, has been reported in Xinjiang. It differs mainly in the presence of a continuous ring of subepidermal sclerenchyma in the leaf blades, which is lacking in H. tians-chanicum and H. mongolicum.