Plants to 2.5 cm. Stem leaves stiff, closely erect-appressed, incurved when dry, oblong-lanceolate or lanceolate, 2--2.7 mm, blunt or obtuse; margins recurved below, reflexed in distal portion, entire; distal laminal cells 6--11 µm wide, 1-stratose, papillae always large, conical or forked; basal laminal cells short-rectangular to quadrate, grading to subquadrate at margin. Sexual condition goniautoicous. Seta 1--1.5 mm. Capsule 1/2 emergent to shortly exserted; urn oblong to short-oblong when old and dry, oblong-ovate to ovate when mature, 1.2--1.9 mm, strongly 8-ribbed entire length, rarely 16-ribbed with 8 short intermediate ribs; stomates immersed in middle and proximal portion, ± completely covered by protruding subsidiary cells; peristome single; endostome segments none; exostome teeth usually 16 when mature, irregularly split, often absent when capsule is old, papillose-striate to coarsely reticulate-papillose. Calyptra oblong, covered with papillose, whitish hairs. Spores 10--15 µm.

Calcareous, more rarely siliceous boulders and cliff faces in xeric areas, often found growing in direct sunlight; 500--3000 m; Greenland; Alta., B.C., Man., N.W.T., Nun., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., S.Dak., Utah, Wyo.; n Europe.

Orthotrichum pellucidum is distinguished by the blunt, lanceolate-oblong leaves that always have a glaucous appearance because of the large forked papillae of the distal leaf cells. When the plants are fertile, which is usually the case, the shortly exserted, oblong-ovate capsule that is eight-ribbed should identify this species.