3. Isothecium Brid. 猫尾藓属 mao wei xian shu
Bryol. Univ. 2: 355. 1827.
Plants usually robust, green to light brown, slightly glossy, in loose patches. Secondary stems ascending, erect, or dendroid, with stipe leaves and creeping branches below, pinnately branched above; branches curved, acute at the apex, not complanately foliate. Leaves loosely appressed when dry, strongly concave, ovate or oblong-ovate at the base, short to long acuminate at the apex, slightly decurrent at the base; margins serrulate or sharply dentate, incurved at the base; costae single, vanishing above mid-leaf; leaf cells rhomboidal or linear, thick-walled; alar cells small, inflated, rounded or quadrate, partly bistratose. Dioicous. Inner perichaetial leaves sheathing at the base, long acuminate at the apex. Setae 1.0–1.5 cm long; capsules erect or horizontal, ovoid or oblong-ovoid, symmetrical or asymmetrical, with slender apophyses; opercula conic, obliquely shortly rostrate; annuli distinctly differentiated; peristome double; exostome teeth lanceolate, yellow, striolate on outer surface, densely trabeculate on inner surface; endostome segments lanceolate, shorter than or as long as the teeth, yellow or hyaline at the tips, finely papillose, rarely smooth; basal membrane high, cilia somewhat developed. Spores spherical, finely papillose.