Plants 1--6 cm, robust. Stem leaves loosely-erect, flexuose when dry, lanceolate, 3--4 mm, narrowly acute to acuminate, appearing revolute to near apex, margins entire; distal laminal cells 7--9 µm wide, 1-stratose, with simple papillae; basal laminal cells elongate, nodose. Sexual condition goniautoicous. Seta 0.8--1.2 mm. Capsule immersed; urn broadly-oblong to narrowly-ovate, 1.5--2.3 mm, smooth; stomates superficial; peristome double; endostome segments 16, in 2 rows of cells, densely papillose; exostome teeth 16, recurved, densely papillose. Calyptra broadly oblong, moderately hairy. Spores 17--31 µm.

Deciduous trees, usually Acer and Alnus trunks in moist woods, less commonly on conifers; 10--1000 m; B.C.; Alaska, Calif., Idaho, Wash., Oreg; Europe; n Africa Asia (India in Kashmir).

This species is distinguished from its closest relatives, O. pycnophyllum, O. speciosum, and O. lyellii, by its ovate, smooth capsule, which is immersed even when dry. The exostome consists of 16 teeth that are recurved, and the endostome consists of 16 erose segments. Orthotrichum striatum is restricted to the Pacific Northwest.