2. Tortella humilis (Hedw.) Jenn., A Manual of the Mosses of Western Pennsylvania. 96:13. 1913; Barbula humilis Hedw., Sp. Musc. Frond. 116, pl. 25, f. 1–4. 1801.
丛叶纽藓
Trichostomum humile (Hedw.) Mach., Cat. Descr. Briol. Portug. 50. 1919.
Mollia caespitosa (Schwaegr.) Broth., Acta Soc. Sci. Fenn. 19(5): 14. 1891. Tortella caespitosa (Schwaegr.) Limpr., Laubm. Deutschl. 1: 600. 1888. Tortula caespitosa (Schwaegr.) Hook. & Grev. in Brewst., Edinburgh J. Sci. 1: 296. 1824. Barbula caespitosa Schwaegr., Sp. Musc. Frond., Suppl. 1, 1: 120, f. 31. 1811.
Plants small, ca. 1 cm high, yellowish green, in loose tufts. Stems erect, usually simple. Leaves strongly crisped when dry, erect-spreading or reflexed when moist, ligulate to narrowly oblong, often channeled above, narrowly acute or bluntly apiculate, somewhat sheathing at base; margins plane or somewhat undulate or narrowly incurved, entire to weakly crenulate with projecting papillae; costa percurrent or ending just below the apex; upper leaf cells quadrate to hexagonal, unistratose, pluripapillose; basal cells often sharply differentiated, rectangular, smooth, forming a V-shaped base. Autoicous. Sporophytes not seen.
Type. USA: Pennsylvania.
Chinese specimens examined: HUNAN: Sang-zhi Co., D.-K. Li 18297 (HKAS, SHM). SHANXI: Ning-wu Co., S.-L. Chang 86044 (HKAS). XIZANG: Ya-dong Co., M. Zang 487 (HKAS); Zhu-mu-long-ma-feng (Mt. Everest), X.-G. Wang 96 (PE). YUNNAN: Kun-ming City, Z.-M. Li s.n. (HYUB).
Habitat: on rocks or forest ground; Distribution: China, Japan, western Asia, Russia, Europe, throughout America, Africa, and Pacific islands.
Illustrations: Zander 1993 (Pl. 18, figs. 1–10).
