2. Trichostomum crispulum Bruch in F. A. Müll. 皱叶毛口藓 zhou-ye mao-kou xian
Flora 12: 395, f. 4. 1829. Didymodon crispulus (Bruch in F. A. Müll.) Wils. in Hook., Brit. Fl. (ed. 4) 2: 30. 1833. Mollia crispula (Bruch in F. A. Müll.) Lindb., Musci Scand. 21. 1879. Tortella crispula (Bruch in F. A. Müll.) Jens., Danmarks Mosser 2: 321. 1923. Type. Europe.
Barbula flavicaulis C. Müll., Nuovo Giorn. Bot. Ital., n. ser. 4: 258. 1897. Type. China: Shaanxi (Schen-si), Lao-y-san, P. J. Giraldi 1384 (isotype H).
Plants small to medium-sized, 10–30 mm high, yellowish green to light brown, in dense tufts. Stems erect, densely foliate, simple or irregularly branched. Leaves crisped when dry, erect-spreading when moist, narrowly lanceolate, acute or acuminate, upper lamina broadly channeled or cucullate, weakly sheathing at base; margins entire, somewhat incurved distally or wavy; costa stout, excurrent as a short awn; upper leaf cells rounded-quadrate, moderately thick-walled, green and obscure, each cell with several large, circular papillae on both surfaces; basal cells slightly elongate, irregularly rectangular, thin-walled, smooth. Dioicous. Setae 10–15 mm long, reddish; capsules erect, short-cylindrical; annuli differentiated, of 3–5 rows of vesiculose cells, persistent; peristome teeth erect, linear, 2-divided, papillose; opercula conic-rostrate, with a long, oblique beak. Spores reddish brown, coarsely papillose.