Culms robust, to 160 cm tall, together with leaf blade and spike usually farinaceous throughout. Leaf sheath glabrous; leaf blade usually rolled, 15–25 × 0.25–0.4 cm, abaxial surface smooth, adaxial surface scabrous. Spike erect or slightly curved, slender, usually dense, 8–15 cm; rachis margin ciliolate. Spikelets 2 per node, purplish green, 10–12 mm, with 2 or 3 florets. Glumes lanceolate or linear-lanceolate, 7–10 mm, 3-veined, ± purplish punctate, scabrous, hispidulous along veins, apex mucronate. Lemma oblong-lanceolate, purplish punctate throughout, pubescent; first lemma 6–9 mm; awn purple, 7–15 mm, pubescent. Palea equaling or subequaling lemma, ciliolate along keels. Fl. and fr. late summer.

In the protologue, the specific epithet was misspelled "pur-pur-aristus" on p. 83, presumably as a typographical error. In the illustration caption on p. 90 it was correctly spelled "purpuraristatus."

* Mountain slopes, valleys. Nei Mongol.