Plants annual. Culms 5–40 cm, erect or ascending. Sheaths glabrous or pubescent; ligules 1.2–2.6 mm, puberulent, obtuse, laciniate; blades 2–15 cm long, 2–5 mm wide, pubescent on both surfaces. Panicles 2–12 cm long, 1–5 cm wide, dense, ovoid, stiffly erect, sometimes racemose; branches shorter than the spikelets, ascending, slightly curved or straight. Spikelets 10–40(45) mm long, 4–10 mm wide, lanceolate to elliptic or oblong, laterally compressed; florets 5–8(10), bases concealed at maturity; rachilla internodes concealed at maturity. Glumes glabrous or pubescent; lower glumes 5–8.5 mm, 3–5-veined, lanceolate; upper glumes 6.5–9.5 mm, 7–9(11)-veined, elliptic; lemmas 8–12(13.5) mm long, 6–7 mm wide, oblanceolate, veins glabrous, scabridulous, or ciliolate, glabrous or pubescent elsewhere, 9–11-veined, rounded over the midvein, margins broadly hyaline, bluntly angled above the middle, not inrolled at maturity, apices subulate to acute or obtuse, toothed, teeth shorter than 1 mm; awns usually 3 on the upper lemmas in each spikelet, arising 2–4 mm below the lemma apices, purple or deep red, central awn 5–25 mm, flattened at the base, divaricate and sometimes twisted at maturity, lateral awns 4–10 mm, erect or reflexed, sometimes absent or much reduced on the lower lemmas; anthers 1–1.8 mm. Caryopses equaling or shorter than the paleas, thin, weakly inrolled or flat. 2n = 14.
Bromus danthoniae is native from the western Asia to southern Russia and Tibet. It was collected in 1904 in Ontario; no other North American collections are known.