绢藓科 juan xian ke
by Hu Ren-liang and Wang You-fang
Plants small, medium-sized to rather robust, or sometimes slender, often green to yellowish green or golden, glossy, in dense mats. Stems prostrate, rarely ascending, regularly branched, densely foliate, complanate or julaceous; central strand present; paraphyllia and pseudoparaphyllia absent. Stem and branch leaves similar, rarely differentiated, sometimes dorsal and lateral leaves slightly differentiated, symmetric or somewhat asymmetric, plane or slightly to strongly concave, ovate, oblong-ovate, ovate-lanceolate, or slenderly lanceolate, obtuse, acute, or acuminate at apex; margins plane, entire or serrulate; costae double, short, sometimes indistinct or absent, rarely reaching to the mid-leaf; median leaf cells rhomboidal to linear, smooth; alar cells numerous, quadrate. Autoicous or dioicous. Male and female plants similar. Perigonia bud-like, small. Perichaetia on short branches. Setae 5–40 mm long, smooth; capsules erect, symmetric, sometimes slightly curved or asymmetric; opercula conic-rostrate, usually with a long beak; annuli developed or absent; peristome double or sometimes exostome reduced or absent; exostome teeth lanceolate or narrowly lanceolate, yellowish or reddish brown, inserted below the mouth, sometimes cross-striolate at base or papillose, rarely smooth, with median zigzag line; endostome segments linear; basal membrane usually not well developed; cilia rudimentary or absent. Calyptrae cucullate, smooth. Spores small, spherical, usually less than 55 µm in diameter, somewhat roughened to finely papillose.