Plants to 13 cm. Stem leaves erect-spreading to loosely-erect, ± contorted when dry, lanceolate to linear-lanceolate, 2.5--6.5 mm, narrowly acute to acuminate; margins plane, entire; distal laminal cells 7--14 µm wide, 1-stratose, with conical papillae; basal laminal cells narrowly-elongate, ± nodose. Sexual condition dioicous. Seta 0.8--2.7 mm. Capsule immersed, emergent, or rarely exserted; urn oblong-cylindric to long-cylindric, 1.7--3 mm, distinctly 8-ribbed from 1/2 to entire length; stomates superficial; peristome double; endostome segments 16, large, coarsely papillose; exostome teeth 16, reflexed-recurved, densely papillose. Calyptra conic-oblong, very hairy. Spores 18--35 µm.

Usually on trees, many times covering entire tree trunks to 10 m, rarely on boulders; 10--1000 m; B.C.; Alaska, Calif. Idaho, Oreg. Wash.; Mexico (Baja California); Europe; n Africa.

This species is easily distinguished from all other species of Orthotrichum by its dioicous sexual condition, the male plants being slightly smaller and having numerous and conspicuous perigonia. In addition, the 16 slenderly acuminate, whitish exostome teeth and 16 endostome segments are characteristic.