Plants: 1–6 cm. Stem: leaves loosely erect, flexuose when dry, lanceolate, 3–4 mm; margins apparently revolute to near apex, entire; apex narrowly acute to acuminate; basal laminal cells elongate, walls thick, nodose; distal cells 7–9 µm, 1-stratose, papillae 2 or 3 per cell, simple, small. : Specialized asexual reproduction absent. Sexual: condition gonioautoicous. Seta: 0.8–1.2 mm. Capsule: immersed, ovate, widest mid capsule, 1.5–2.3 mm, smooth; stomata superficial; peristome double; prostome absent; exostome teeth 16, separate to base, recurved, acute, densely papillose; endostome segments 16, well developed, usually present when capsule is old and dry, thick, stout, of 2 rows of cells, narrower than exostome teeth, erose, yellowish brown, densely papillose. Calyptra: broadly oblong, smooth, moderately hairy, hairs smooth. Spores: 17–31 µm.
Deciduous trees, on Acer and Alnus trunks in moist woods, conifers. low to moderate elevations (10- 1000 m). B.C., Alaska, Calif., Idaho, Oreg., Wash., Europe, Asia (India in Kashmir), n Africa.
Orthotrichum striatum is distinguished from its closest relatives, O. lyellii, O. pycnophyllum, and O. speciosum, by its ovate, smooth capsules, which are immersed even when dry. The exostome of O. striatum consists of 16 recurved teeth, and the endostome of 16 erose segments. In the flora area, O. striatum is restricted to the Pacific Northwest.