4. Barbella M. Fleisch. ex Broth. 悬藓属 xuan xian shu
Nat. Pflanzenfam. I(3): 823. 1906.
Plants often small, sometimes medium-sized, slender, soft, yellowish green, glossy to somewhat glossy. Primary stems creeping, filiform, sparsely foliate, subpinnately branched; secondary stems often complanately foliate, prostrate or pendulous; branches elongate, slender, pendulous, rarely on substrates. Stem leaves appressed when dry, erect-spreading when moist, oblong, ovate, or oblong-ovate at the base, gradually narrowed to a short to long, slender to piliferous apex; margins serrulate, sometimes undulate above; costae single, slender, reaching to mid-leaf, rarely absent; leaf cells elongate-rhomboidal to linear, uni- to pluripapillose, usually thin-walled; apical cell slightly thick-walled; basal juxtacostal cells rectangular or quadrate, thick-walled; alar cells more or less differentiated, quadrate or subquadrate; branch leaves similar to stem leaves, usually more complanate, not appressed; axillary hairs up to 7–8 cells long, hyaline. Dioicous or autoicous. Perichaetia on branches or stems; inner perichaetial leaves lanceolate, ecostate or with a very short costa. Setae short, often curved, smooth or scabrose; capsules erect, oblong-ovoid or cylindrical; opercula conic-rostrate; annuli usually not differentiated; peristome double; exostome teeth narrowly lanceolate, papillose throughout, lamellae high; endostome segments linear-lanceolate, as long as or slightly shorter than the teeth, often keeled, perforate; basal membrane high; cilia rudimentary or absent. Calyptrae mitrate, lobed or cucullate, smooth or hairy. Spores spherical, finely papillose.