6. Ectropothecium Mitt. 偏蒴藓属 pian shuo xian shu
J. Linn. Soc., Bot. 10: 180. 1868. Hypnum sect. Ectropothecium (Mitt.) Ångstr., Öfvers. Förh. Kongl. Svenska Vetensk.-Akad. 30(5): 125. 1873.
Plants slender to rather robust, yellowish green or brownish green, glossy or not glossy. Stems prostrate, sometimes pendulous, ascending or erect when in dense mats, radiculose, simple or pinnately branched, branches ascending, usually complanate; paraphyllia absent, pseudoparaphyllia filamentous or lanceolate to foliose. Stem leaves and branch leaves heteromorphic, or more or less similar, ovate- or obovate-lanceolate, somewhat asymmetric, often falcate-secund, not decurrent at base, usually dorsal, ventral, and lateral leaves differentiated; costae double, short, very weak, or distinct; leaf cells linear, sometimes distinctly prorate; basal cells shorter and broader; alar cells few, small, quadrate or shortly rectangular, usually not particularly inflated, but with one or two cells clearly distinct. Autoicous or dioicous. Inner perichaetial leaves broadly lanceolate, gradually acuminate or suddenly narrowed to a slender acumen. Setae elongate; capsules horizontal to inclined, small to very small, ovoid to urceolate or shortly cylindrical, often constricted below the mouth when dry; exothecial cells sometimes mammillose; opercula inflated, conic, apiculate to shortly rostrate; annuli differentiated; peristome double; exostome teeth narrowly lanceolate, not bordered, cross-striate on the outer surface, trabeculate on the inner surface; endostome segments linear-lanceolate, with a high basal membrane and 2–4 cilia. Calyptrae cucullate, smooth, sometimes hairy. Spores small, usually smooth.