Plants: 0.3–1 cm. Stem: leaves loosely erect-appressed and slightly incurved when dry, oblong-lanceolate to broadly lanceolate, 1.6–3 mm; margins recurved to near apex, entire or crenulate at apex; apex narrowly obtuse, acute, or apiculate; basal laminal cells rectangular, walls thin, not nodose; distal cells 9–14 µm, 1-stratose, papillae 2 or rarely 3 per cell, conic, low. : Specialized asexual reproduction occasional, by gemmae on leaves. Sexual: condition cladautoicous. Seta: 0.5–1.5 mm. Capsule: emergent to barely exserted, oblong to oblong-cylindric, 1–2.5 mm, strongly 8-ribbed, narrowly cylindric and contracted along entire length when old; stomata immersed, to 1/2 covered by subsidiary cells, cells not projecting, inner walls not much thickened; peristome double; prostome absent; exostome teeth 8, erect, reflexed or recurved-reflexed with age, finely papillose, densely papillose, or papillose-striate; endostome segments 8 or 16, well developed, of 1 or 2 rows of cells, smooth or finely papillose. Calyptra: conic-oblong, smooth, naked or sparsely hairy, hairs smooth. Spores: 10–20 µm. North America, Mexico, Europe.
Varieties 9 (3 in the flora). Orthotrichum pallens is distinguished by the immersed stomata that are scarcely covered by thin-walled subsidiary cells. The peristome is double with a well-developed endostome of 16 (or eight) segments that remains intact until the capsule is quite old. Gametophytically, O. pallens is distinguished by narrowly obtuse, oblong-lanceolate leaves, and an autoicous sexual condition.
Stem: leaves oblong-lanceolate to lanceolate; margins entire; apex narrowly obtuse to broadly acute. Seta: 0.5–1.5 mm. Capsule: oblong-cylindric, 1.3–2.5 mm; exostome teeth reflexed, densely papillose; endostome segments 16, of 2 rows of cells, as long as exostome, papillose. Calyptra: naked. Spores: 10–17 µm.
Trunks and branches of trees, dry, calcareous or granitic rock along streams. moderate to high elevations (300-3000 m). Alta., B.C., Man., Nfld. and Labr. (Nfld.), Nunavut, Ont., Que., Yukon, Ariz., Calif., Colo., Mich., Minn., Mont., Nev., S.Dak., Utah, Mexico (Nuevo León), Europe.
Variety pallens has entire leaf margins, 16 endostome segments, and a naked calyptra.