Bromus pumpellianus subsp. pumpellianus
Plants rhizomatous. Culms 50-120 cm, erect; nodes 2-3 (4), usually pubescent, sometimes glabrous; internodes glabrous or pubescent. Sheaths pilose, villous, or glabrous; auricles present on the lower leaves or absent; ligules to 3 mm; blades 9-17 (25) cm long, (3) 4-8 (9) mm wide, abaxial surfaces glabrous or pilose, adaxial surfaces usually pilose, rarely glabrous. Panicles 10-20 cm, open or contracted, erect or nodding; branches erect to spreading. Spikelets 20-30 mm. Glumes glabrous, pubescent, or hirsute; lower glumes (4) 5-9 mm, 1-veined; upper glumes (5) 8-11 mm, 3-veined; lemmas 9-14 mm, pubescent on the lower portion of the back and along the margins; awns usually present, to 6 mm, sometimes absent; anthers 3.5-7 mm. 2n = 56.
"decumbent" is not a number.