5. Oligotrichum semilamellatum (Hook. f.) Mitt. 半栉小赤藓 ban zhi xiao chi xian
J. Proc. Linn. Soc., Bot., Suppl. 2: 150. 1859. Polytrichum semilamellatum Hook. f., Icon. Pl. 2: 194A. 1837. Type: the Himalayas.
Plants medium-sized, 1–3 cm high, female plants slightly larger than the male ones, brownish green to reddish brown, erect, aggregate or scattered. Stems with weakly developed central strand; rhizoids numerous at base. Leaves lanceolate, sheathing or concave at base, loosely arranged, upper leaves usually revolute when dry, erect-spreading when moist; middle leaves 2.5–4.5 mm × 0.5–0.8 mm, sheathing or often clasping at base; margins serrate; costa somewhat broad, vanishing below the apex; ventral lamellae longitudinally undulate or crisped, usually 5–6 rows, 3–6 cells high; on the leaf back, sometimes with low lamellae, 1–3 cells high; leaf cells unistratose; median cells rounded quadrate, 10–15 µm wide; basal cells mostly elongate, 20–45 µm long, rather thin-walled. Dioicous. Perigonia in rosettes, often with innovations in the center. Setae reddish brown, straight; capsules oblong-ovoid to shortly cylindrical, mostly asymmetric, single; peristome teeth single layer, 32, membrane somewhat high; opercula conic at base, shortly beaked. Calyptrae cucullate, smooth, with a few short cilia at apex. Spores spherical, 9–15 µm in diameter, finely papillose.