Grimmia cinclidodontea Müller Hal., Bot. Centralbl. 44: 387. 1890; G. pacifica Lawton

Plants in open, occasionally compact tufts or mats, olivaceous, brownish, or nearly black. Stems 1-8 cm, sometimes denuded of leaves at base, central strand absent. Leaves usually curved to falcate, sometimes falcate-secund when dry, linear-lanceolate to ovate-lanceolate, concave proximally, weakly keeled or concave distally, 1.4-5 mm, mainly 2-stratose distally and with 2-stratose strips extending to leaf base adjacent to costa; margins plane or somewhat erect, rarely weakly recurved, smooth, 2-stratose; apices rounded or acute, usually ending in a fleshy, multistratose apiculus, rarely tipped with a short, denticulate awn; costa percurrent, rarely short-excurrent, smooth; basal marginal cells quadrate or short-rectangular; distal cells quadrate or rounded, often angular, 6-11 µm wide, smooth, sometimes weakly bulging-mammillose, weakly sinuose. Sexual condition autoicous. Capsule reddish brown, ovoid, cupulate, or short-cylindric, 1.3-1.8 mm; exothecial cells mostly short-elongate or isodiametric, usually irregularly angular, thin-walled, sometimes trigonous; rim darker colored than capsule wall, often red; stomata absent; peristome patent, 350-600 µm, red, finely papillose, strongly perforated. Spores 8-13 µm, smooth.

Capsules mature late spring to early summer. Wet or dry rocks, often along intermittent watercourses; high elevations (2000-3500 m); Calif., Idaho, Oreg., Wash; Europe.

Schistidium cinclidodonteum and the closely related S. occidentale are characterized by the long, often linear-lanceolate and falcate leaves. Both species often form large, rather flat mats over rock along watercourses. The proboscis-like (discussed in S. Flowers 1973) fleshy apiculus distinguishes the two from all other species of the genus except S. crassithecium, which differs in having a much smaller apiculus, and more erect, ovate-lanceolate leaves. Examination of the type of Grimmia pacifica, not recognized here, reveals that the only salient difference between that taxon and S. cinclidodonteum is the presence of a short, denticulate awn.