Plants not cespitose, strongly rhizomatous, often glaucous. Culms 35–75 cm tall, 1–2.5 mm thick, solitary or a few together, glabrous or sparsely pubescent near the nodes. Leaves exceeded by the spikes; sheaths glabrous, smooth;auricles infrequently present, to 0.8 mm, the auricular location often with hairs to 2 mm; ligules 0.3–0.5 mm, truncate, erose; blades 4–29 cm long, 1–2(5) mm wide, flat, becoming involute when dry, stiff, adaxial surfaces scabrous, with scattered hairs to 2 mm, veins 7–11, subequal, prominently ribbed. Spikes 1.5–25 cm long, 4–10 mm wide, with 1 spikelet per node at midspike, sometimes with 2 at the lower nodes; internodes 7–12 mm, surfaces glabrous or strigillose, edges ciliate, cilia to 1 mm. Spikelets 16–25 mm, pedicellate, pedicels 1–2(5) mm, with 3–12 florets. Glumes subequal, 8–12 mm long, 0.5–1.5 mm wide, subulate, tapering from about 1/4 of their length, stiff, glabrous at least at the base, the central portion thicker than the margins, keeled, 0–1(3)-veined, veins inconspicuous at midlength; lemmas 7–12 mm, glabrous, awned, awns 2.3–6.5(12) mm; anthers 3.7–4.5 mm, dehiscent. 2n = 28.
Leymus simplex is found in meadows and drifting sand in southern Wyoming, and along the Green River in northeastern Utah.