树灰藓科 shu hui xian ke
by Li Xing-jiang and Si He
Plants robust. Primary stems creeping, with dense rhizoids; secondary stems dendroid, simple below, branched above, sometimes pinnately branched; central strand differentiated; outer cortical cells dark colored, thick-walled; inner cortical cells parenchymous, thin-walled. Leaves in multi-rows, unistratose, sometimes bistratose at margins in some species, usually symmetric, not decurrent at base, ovate-lanceolate to narrowly lanceolate; margins sharply dentate above, sometimes double-toothed; costae single, strong, percurrent or shortly excurrent, often dentate at back, in cross section stereid bands well developed; leaf cells elongate, sometimes dorsally papillose, rarely oblong-hexagonal, smooth; basal cells shorter, thick-walled, porose; alar cells not or sometimes differentiated; branch leaves similar to stem leaves or dimorphic. Dioicous. Perichaetia and perigonia on secondary stems or on tips of short branches, paraphyses filamentous. Perigonia disk-like. Setae elongate, thick, straight, reddish, smooth; capsules erect, inclined to horizontal, ovoid, oblong-ovoid or cylindrical; neck distinctly differentiated; opercula conic at base, usually rostrate; annuli differentiated; peristome double; exostome teeth lanceolate or narrowly lanceolate, bordered, with a median zigzag line, trabeculate; endostome segments yellowish, as long as the teeth, lanceolate, widened at base, keeled, mostly perforate; basal membrane high; cilia 3–5, nodulose. Calyptrae cucullate, smooth. Spores small, spherical.