Kendrick L. Marr Richard, J. Hebda and Craig W. Greene†
Plants sometimes with sterile culms; usually densely cespitose, occasionally with rhizomes shorter than 1 cm. Culms (25)35–45(60) cm, unbranched, smooth or slightly scabrous beneath the panicles; nodes 1–2. Sheaths and collars smooth; ligules (2.5)3.5–6 mm, acute, lacerate; blades (9)12–20(25) cm long, 1–2.5(3) mm wide, flat to involute, abaxial surfaces smooth, adaxial surfaces finely scabrous, glabrous or sparsely hairy. Panicles(5)7–12(15) cm long, (2)3.5–6.5(8) cm wide, loose, open, straw-colored or green to purplish; branches (2)3.5–5(7) cm, smooth or sparsely scabrous, spikelets usually confined to the distal 1/2. Spikelets (5.5)6–8 mm; rachilla prolongations 1–1.5(2) mm, hairs (1.5)2–2.5(3) mm. Glumesrounded to slightly keeled, smooth or scabrous distally, lateral veins usually prominent and raised, apices acuminate; callus hairs 2–3(4.5) mm, 0.4–0.6(0.7) times as long as the lemmas, abundant; lemmas 4.5–5 mm, about 2 mm shorter than the glumes; awns (10)13–16 mm, attached to the lower 1/5–2/5 of the lemmas, exserted, stout, easily distinguished from the callus hairs, strongly bent; anthers (2)2.5–3(4) mm. 2n = 28.
Calamagrostis howellii grows on dry rocky slopes, banks, ledges, and in cliff crevices, sometimes on basalt, from 100–450 m. It grows only in the Columbia River Gorge of Washington and Oregon.