4. Orthomnion Wils. 立灯藓属 li deng xian shu
Hooker's J. Bot. Kew Gard. Misc. 9: 368. 1857. Orthomnium Wils. ex Broth., Öfvers. Förh. Finska Vetensk.-Soc. 47: 7. 1905, hom. illeg.
Orthomniopsis Broth., Öfvers. Förh. Finska Vetensk.-Soc. 49(10): 1. 1907.
Plants medium-sized to rather large, deep green when young, reddish brown when old, in loose tufts. Primary stems prostrate or suberect, with reddish brown rhizoids; secondary stems erect, simple, with rhizoids at base, densely foliate above. Leaves crisped when dry, spreading when moist, rounded-ovate, obovate or broadly spathulate, narrowed at base, obtuse or abruptly acute or apiculate at apex; margins entire, bordered by 1–4 rows of narrower cells or somtimes scarcely bordered; costae thick at base, slender upward, ending above mid-leaf or below the apex, rarely percurrent or shortly excurrent; leaf cells lax, mostly elliptical or hexagonal, elongate toward base. Dioicous. Perichaetial leaves similar to vegetative ones, smaller. Setae clustered, elongate, yellowish; capsules erect, ellipsoidal; neck short; mouth narrowed, reddish brown, smooth; opercula conic, apiculate to shortly rostrate; annuli lacking; peristome double; exostome teeth whitish, lanceolate, densely papillose; endostome segments reduced, often with only basal membrane remaining; cilia lacking. Calyptrae cucullate, mostly hairy. Spores spherical.