12. Orthotrichum hallii Sull. & Lesq. 半裸蒴木灵藓 ban luo shuo mu ling xian
Icon. Musc. Suppl. 63, pl. 45. 1874. Type: U.S.A. Colorado.
Plants medium-sized, olive-green or yellowish brown above, brown or black below, in dense mats. Stems ca. 2.5 cm long, remotely branched. Leaves loosely arranged when dry, erect-spreading or spreading when moist, elongate-lanceolate to lanceolate, 1.7–3.5 mm long, obtuse, rarely acute, usually bistratose in the upper part; margins entire, plane above, reflexed or recurved below; costae slender, subpercurrent; upper leaf cells irregularly rounded-hexagonal, 7–13 µm wide, not hyaline, with 1–3 conic protruding papillae per cell, irregularly thick-walled; lower cells shortly rectangular to rectangular, becoming quadrate and hyaline toward margins. Gemmae not seen. Goniautoicous. Setae 0.5–1.0 mm long; capsules immersed, oblong-ovoid to shortly cylindrical, 1.0–1.8 mm long, furrowed; exothecial cells differentiated in longitudinal bands, constricted at the mouth; stomata immersed; peristome double; prostome present; exostome teeth 8, sometimes irregularly splitting into 16, pale, recurved when dry, rarely reflexed, striolate or papillose; endostome segments 8, short, distinctly longitudinally striolate. Calyptrae oblong-conic, rarely plicate, hairy. Spores 10–17 µm in diameter, roughly papillose.