Plants loosely cespitose, occasionally rhizomatous. Culms 60–110 cm tall, 1–1.5 mm thick, many together. Leaves exceeded by the spikes; sheathsglabrous or sparsely pubescent; auricles to 1.1 mm; ligules 0.2–1.2 mm, truncate; blades 2.5–6 mm wide, flat, adaxial surfaces scabridulous, glabrous, veins (9)11–17, unequal, not crowded. Spikes 8–17 cm long, 5–10 mm wide, erect, with 2 spikelets at most nodes; internodes 4–11 mm, surfaces hairy distally, hairs 0.2–0.8 mm, edges ciliate. Spikelets 12–23 mm, with 2–7 florets. Glumes unequal, 0.5–2.5 mm wide, tapering from below midlength to the subulate apices, stiff, keeled, the central portion thicker than the margins, glabrous, scabrous, particularly distally, bases not overlapping, 0–1(3)-veined, veins inconspicuous at midlength; lower glumes 2–9.5 mm; upper glumes 6–14 mm; calluses with hairs, hairs about 0.2 mm; lemmas 8–14.5 mm, glabrous or sparsely strigose, awned, awns 1.3–7 mm; anthers 3.5–7 mm, dehiscent. 2n = 28.
Leymus ambiguus grows on steep, often boulder-strewn hillsides at scattered locations in Colorado and New Mexico.