牛舌藓科 niu-she xian ke
by Wu Peng-cheng, Jia Yu, and Wang Mei-zhi
Plants small or robust, light green, yellowish green or brownish green, in loose or dense mats, rarely pendulous. Stems or primary stems creeping, secondary stems erect or ascending, irregularly pinnately or irregularly remotely branched, apices curved or caudate, often with asexual creeping branches; central strand present or absent; paraphyllia mostly lacking. Stem leaves and branch leaves similar or nearly identical, imbricate or erect-spreading when dry; stem leaf bases ovate or oblong ovate, acuminate or suddenly narrowed into a linear-lingulate or lanceolate apex, rarely transversally undulate or ovate to widely ovate, with acute apices; leaf margins plane or undulate, minutely serrate or minutely rounded-papillose, rarely remotely dentate or irregularly grossly serrate; costa single, up to the middle, rarely rigid, nearly reaching leaf apices; leaf cells rhomboidal, hexagonal or ovate-rhomboidal, thin-walled, multipapillose or thick-walled and smooth; basal median leaf cells ovate or oblong, hyaline at both sides of costa. Branch leaves smaller and narrower or slightly larger than stem leaves. Monoicous or dioicous. Perichaetial leaves usually large, sheathing at base, rarely small, gradually acuminate or lanceolate to a long subula. Setae slender, 5–20 mm long; capsules usually ovoid, rarely cylindrical or ovoid-cylindrical, smooth, stomata sparse or absent; annuli mostly differentiated; opercula conical, beaked; exostome teeth usually light yellow, rarely brownish yellow, papillose above, smooth or weakly striate at base; endostome segments usually short, rudimentary or absent or sometimes well developed, basal membrane low. Calyptrae cucullate, smooth, rarely papillose or ciliate. Spores nearly spherical, densely minutely papillose.