Bromus sect. Mexibromus Saarela, P.M. Peterson & Valdés–Reyna, sect. nov.

Type:— Bromus densus Swallen

Differs from other infrageneric taxa of Bromus by its 3(–5)-nerved lemmas.

Plants perennial, loosely to densely tufted, not rhizomatous. Culms up to 192 cm tall, erect, glabrous to pubescent below inflorescence; nodes 2–6, glabrous to pubescent. Leaf sheaths glabrous or pubescent; auricles absent or present; ligules 0.4–1.5(–3) mm long; blades up to 74 cm × 2–16 mm, flat, linear or attenuate proximally, glabrous to pilose. Panicles up to 33 cm long, open, nodding, 1–4 spikelets per branch. Spikelets (1.5–)2–3.6(–4) cm long, 5–8-flowered, elliptic, lanceolate to linear-lanceolate, terete to moderately laterally compressed; glumes usually glabrous, sometimes weakly pubescent; lower glumes 6.5–13(–14) mm long, narrowly lanceolate to lanceolate, apices acute, rarely acuminate, 1(–3)-nerved; upper glumes 8–19 mm long, lanceolate to obovate-lanceolate, apices obtuse, acute, acuminate or mucronate, 3-nerved. Lemmas 10–20 mm long, elliptic, lanceolate or linear-lanceolate, rounded over the backs, 3(–5)-nerved, glabrous to pubescent; awns (1–) 2–13 mm long; anthers 1.1–6.5 mm long; caryopses 6–15 mm long.

Included species:— Bromus attenuatus, B. densus, B. dolichocarpus .