4. Ctenidium (Schimp.) Mitt. 梳藓属 shu xian shu
J. Linn. Soc., Bot. 12: 509. 1869. Ctenidium subgen. Eu-Ctenidium Broth., Nat. Pflanzenfam. I(3): 1048. 1908. Hypnum sect. Ctenidium (Schimp.) De Not., Cronac. Briol. Ital. 2: 29. 1867. Stereodon sect. Ctenidium (Schimp.) Mitt., J. Linn. Soc. Bot. 8: 153. 1864. Hypnum subgen. Ctenidium Schimp., Syn. Musc. Eur. 631. 1860.
Plants slender to robust. Stems prostrate or somewhat ascending, rarely suberect, regularly or irregularly pinnately branched; branches remote or dense; stem rounded or elliptic in cross section, epidermal cells small, outer cortical cells 3–5 layers, central strand slightly developed; rhizoids reddish brown, papillose; pseudoparaphyllia rounded foliose or triangular, short to long-acuminate, laciniate at margins. Stem leaves and branch leaves distinctly differentiated; leaves densely arranged, falcate-secund, usually cordate and decurrent at base, not or slightly plicate, abruptly narrowed to slenderly acuminate apex; margins serrate; costae double, short or indistinct; leaf cells linear, often prorate; alar cells quadrate or shortly rectangular, sometimes inflated; branch leaves narrower, ovate-lanceolate. Dioicous, rarely autoicous. Inner perichaetial leaves erect, oblong-ovate at base, abruptly slenderly acuminate at apex, sheathing base with hairs. Setae elongate, reddish, smooth or nearly smooth; capsules inclined to horizontal, ovoid or oblong-ovoid, arcuate; opercula conic, shortly or bluntly rostrate; annuli differentiated, deciduous; peristome double; exostome teeth lanceolate, united at base, orange or golden and cross-striate at base, hyaline and papillose above on the outer surface, trabeculate on the inner surface, bordered; endostome segments linear-lanceolate, yellowish, perforate, papillose; basal membrane low; cilia 2–3, nodulose. Calyptrae cucullate, hairy. Spores yellowish brown, nearly smooth.