Leon E. Pavlick and Laurel K. Anderton

Plants perennial. Culms 45–120(180) cm tall, to 3 mm thick. Sheaths usually sparsely retrorsely pilose throughout, ranging from densely pilose to glabrous, except at the throat, throats always pilose; auricles sometimes present on the lower leaves; ligules 1–3.5 mm, sparsely hairy, acute to obtuse, erose or lacerate; blades 8–25 cm long, 1–12 mm wide, flat or involute, glabrous or sparsely pilose to pubescent on 1 or both surfaces. Panicles 5–20(30) cm, erect; lower branches shorter than 10 cm, 1–4 per node, erect or ascending. Spikelets with 4–9 florets. Glumes sometimes pubescent; lower glumes 7–11 mm, 3–7(9)-veined; upper glumes 9–13 mm, 5–9(11)-veined; lemmas 10–14(17) mm, coriaceous, strongly keeled at least distally, pubescent on the backs and margins, on the margins only, or glabrous, 7–9-veined; awns 4–7 mm; anthers 1–6 mm. 2n = 42.

Bromus carinatus var. marginatus is primarily an inland species and grows on open slopes, grass balds, shrublands, meadows, and open forests, in montane and subalpine zones. It grows from British Columbia to Saskatchewan, south throughout the western United States, and also extends into northern Mexico. Its elevational range is 350–2200 m in the northern part of its distribution, and 1500–3300 m in the south.

Bromus carinatus var. marginatus is variable, and intergrades with B. carinatus var. carinatus to the west, B. aleutensis to the north, and B. polyanthus to the southeast. As treated here, B. carinatus var. marginatus includes B. luzonensis J. Presl, which has been recognized mainly on the basis of its canescent sheaths and blades; this trait seems highly variable and may be environmentally determined. Although the name Bromus carinatus var. marginatus was attributed to Hitchcock by Scoggan, there is no evidence that either A.S. or C.L. Hitchcock actually made the combination.