Kendrick L. Marr Richard, J. Hebda and Craig W. Greene†
Plants usually with sterile culms; usually cespitose, often with rhizomes 2–15 cm long, 1–3 mm thick. Culms (30)55–80(100) cm, unbranched, scabrous beneath the panicles; nodes (1)2(5). Sheathsandcollars usually scabrous, rarely smooth; ligules (0.5)2–5.5(7) mm, usually truncate, entire to slightly lacerate; blades (8)10–20(27) cm long, (1.5)2–3(4) mm wide, usually involute, abaxial surfaces usually scabrous, rarely smooth, adaxial surfaces scabrous, glabrous or sparsely hairy, both surfaces with abundant white glands between the veins, visible only with magnification. Panicles (6)8–11(15) cm long, (1)1.2–1.5 cm wide, contracted, mostly erect, pale green to green; branches 2–4(4.5) cm, scabridulous, usually spikelet-bearing to the base. Spikelets(4.5)5–7(8) mm; rachilla prolongations about 1.5 mm, hairs 1–2 mm. Glumes keeled, usually scabrous over the entire surface, rarely only the keels scabrous distally, lateral veins prominent, apices acute to acuminate; callus hairs 1–1.5(2) mm, 0.2–0.4 times as long as the lemmas, sparse; lemmas 4.5–6.5 mm, 0–2 mm shorter than the glumes; awns5–6(8)mm, attached to the lower 1/10–1/5 of the lemmas, exserted less than 2 mm, stout, distinguishable from the callus hairs, bent; anthers (2.5)3–3.5(4) mm. 2n = 28.
Calamagrostis ophitidis grows in meadows, seeps, grasslands, and chaparral, as well as in coniferous forests, on serpentine outcrops and soils, at 85–1065 m. It is known only from Sonoma, Marin, Mendocino, Lake, and Napa counties in California.