Plants to 12 mm. Stem leaves erect-appressed when dry, ovate-lanceolate to oblong-lanceolate, 2.5--4 mm, acute or rarely narrowly obtuse; margins recurved or revolute to near the apex, entire; distal laminal cells 8--12 µm wide, 1-stratose, or occasionally areas with 2-stratose, densely pluri-papillose with 2--3 large, forked papillae or papillae sometimes small and conical; basal laminal cells long- to short-rectangular, non-nodose. Sexual condition goniautoicous. Seta 0.5--1 mm. Capsule immersed to 1/2 emergent when dry; urn ovate-pyriform to sometimes short-oblong, 1.2--1.6 mm, ± 0.8 mm wide, 16-ribbed; stomates immersed, in 1 or 2 rows in the middle of the capsule; peristome single, rarely double; endostome segments rarely present, 8, 1 row of cells wide, smooth; exostome teeth 16, erect, becoming spreading-reflexed with age, usually not present when the capsule is old, papillose-striate or papillose-reticulate. Calyptra oblong to oblong-conic, with papillose hairs. Spores 9--16 µm.

Faces of calcareous cliffs and large boulders in coniferous forests, most common in the dryer areas of Ponderosa Pine forests and on the dryer cliff faces in canyons; 100--3000 m; B.C.; Ariz., Calif., Colo., Idaho, Mont., Nev., Oreg., S.Dak. Texas, Utah, Wash., Wyo.; Mexico (Nuevo León). Europe; Asia; n Africa.

Orthotrichum cupulatum is extremely variable but can be distinguished by the following combination of characters most of which are usually evident: (1) leaves broadly but sharply acute, ovate-lanceolate, and usually 1-stratose or occasionally partially 2-stratose; (2) papillae of the leaf cells usually large and forked, but if small and conical then the leaf is 1-stratose; (3) margin of leaf never thicker than lamina; (4) peristome teeth always 16, erect or spreading, and yellow-brown; and (5) capsule 16-ribbed, sometimes with 8 short and 8 long ribs.