Flora of China 22: 182

Plants annual. Culms 20-40 cm tall, slender, erect or geniculately ascending, sparsely hairy. Leaves: sheaths pubescent; ligule about 2 mm long;  blade 10-15 cm long, about 3 mm wide, both surfaces pubesent, margins scabrous. Panicle 4-10 cm long, 3-5 cm wide, ovate in outline, lax; branches 4-8 per node, 2-6 cm long, glabrous, each bearing 1-4 spikelets. Spikelets 5-8 mm long with 3-6 florets, broadly elliptic, internodes visible; lower glume 3-4 mm long, 1-veined, lanceolate; upper glume 4-5 mm long, 3-veined, narrowly ovate, margins membranous, tip acuminate; lemmas 3.5-4.5 mm long, 5-7-veined, oblanceolate, margins strongly inrolled and sparsely ciliolate, tip minutely 2-toothed, awned from the sinus; awn 15-20 mm long, slender, straight; palea subequal to the lemma, keels ciliolate; anthers 0.3-0.5 mm long.

2n = 14. 

Bromus gracillimus flowers from June to August [in China]. It grows aon mountain slopes, river banks, and in grassy places among thickes at 2000-3400(-4200) m.