Plants perennial; loosely cespitose. Culms 20-70 cm tall, to 3 mm thick, sometimes geniculate at the base. Sheaths usually smooth or scabridulous, sometimes slightly pubescent distally, not pilose at the throat; auricles absent; ligules 1-6 mm, densely hairy to ciliolate, acute to obtuse, erose; blades 6-13 cm long, 6-8 mm wide, flat, both surfaces glabrous, smooth or scabrous. Panicles 9-20 cm long, 2-2.5 cm wide, dense; lower branches shorter than 10 cm, 2-4 per node, erect, with 1-2 spikelets variously distributed. Spikelets 20-40 mm, usually longer than the branches and pedicels, elliptic to lanceolate, strongly laterally compressed, crowded, overlapping, with 3-7 florets. Glumes pubescent; lower glumes 8-12 mm, (3)5(7)-veined; upper glumes 10-13 mm, 7(9)-veined, shorter than the lowest lemma; lemmas 12-14 mm, lanceolate, laterally compressed, distinctly 9-11-veined, strongly keeled at least distally, more or less uniformly hairy, often with bronze hyaline margins, apices entire or with acute teeth shorter than 1 mm; awns (2)4-7 mm; anthers 2-4 mm. 2n = 56.

Bromus maritimus grows in coastal sands from Lane County, Oregon, to Los Angeles County, California.

Bromus carinatus is native from British Columbia to Saskatchewan and south to Mexico. It has been introduced to various more eastern locations, and to the southern Yukon Territory. The two varieties recognized here are sometimes recognized as species.