2. Leucobryum Hampe 白发藓属 bai-fa xian shu
Linnaea 13: 42. 1839.
Plants small to large, sometimes robust, 0.5–20 cm high, whitish, grayish or bluish green, in compact or loose cushions. Stems erect, simple or forked; central strand mostly absent, sometimes present. Leaves crowded, appressed, or erect-spreading, sometimes falcate-secund above, linear-lanceolate to lanceolate or subtubulose from oblong-ovate to elliptic sheathing base, acute to mucronate at the apex, often with rhizoids at leaf tips, upper parts of leaves filled mostly by the multi-layered broad costa, laminae confined to the basal parts of leaves with multi-rowed linear cells; alar cells rarely differentiated; margins entire to slightly serrulate at the apex, ± bordered by linear cells up to the leaf apex; costae thick, broad, consisting of 2–8 layers of enlarged leucocysts enclosing a ± median row of small, quadrangular chlorocysts in cross section near leaf base. Dioicous or pseudoautoicous. Male plants dimorphous, sometimes minute, dwarf male plants growing on tomentum or among leaves of female plants; normal male plants as large as female plants. Perichaetial leaves sheathing at the base, abruptly linear-filiform from shoulders. Sporophytes terminal or lateral. Setae erect, elongate, sometimes clustered; capsules more or less cylindrical, asymmetric, inclined to horizontal, rarely erect, ± ribbed, often strumose; stomata lacking; annuli often absent, 1–2 rows of small cells when present; opercula long-rostrate; peristome teeth 16, divided to the middle, lanceolate with a broad base, vertically striolate below and papillose above on inner surface, papillose or smooth on outer surface. Calyptrae cucullate. Spores small to large, finely papillose.