Bryol. Univ. 1: 596, plate 5, fig. 5. 1826.
Plants in dense tufts, dull olive green to brownish. Stems 2–10 cm, erect to ascending, 2-fid; triangular in cross section, hyalodermis present, epidermis not prorulose; radiculose proximally, rhizoids papillose. Leaves in 3 rows, laxly erect or erect-spreading and somewhat curved when dry, erect-spreading when moist, narrowly lanceolate, 1-stratose, often 2-stratose at distal margins; base not sheathing; margins revolute nearly throughout, often serrate distally, teeth paired; apex acuminate; costa percurrent to short-excurrent, abaxial surface serrulate; basal laminal cells longer than distal cells; distal cells subquadrate or short-rectangular, faintly striate, walls thick. Specialized asexual reproduction unknown. Sexual condition synoicous; perigonia absent; perichaetial leaves scarcely distinct. Seta single, elongate, straight or flexuose. Capsule suberect, subglobose, furrowed when dry, mouth small; annulus absent; operculum short-conic or convex; peristome double; exostome teeth reddish brown, lanceolate, smooth or minutely papillose, apically free; endostome yellowish to hyaline, segments broad, cilia short, rudimentary, or absent. Spores ellipsoid, coarsely papillose.
Nearly worldwide, except Antarctica.
Plagiopus is distinguished by its triangular stems, striated laminal cells, and leaves appearing papillose in cross section.