8. Ditrichum pusillum (Hedw.) Hampe 细叶牛毛藓 xi-ye niu-mao xian
Flora 50: 182. 1867. Didymodon pusillus Hedw., Sp. Musc. Frond. 104. 1801. Type. Austria.
Ditrichum microcarpum Broth. in Handel-Mazzetti, Symb. Sin. 4: 12. 1929. Type. China: Yunnan, Handel-Mazzetti 6264 (holotype H).
Ditrichum setschwanicum Broth. in Handel-Mazzetti, Symb. Sin. 4: 12. 1929. Type. China: Sichuan, Yen-yuan Co., Handel-Mazzetti 2859 (holotype H; isotype MO).
Ditrichum tortile (Schrad.) Brockm., Arch. Ver. Freund. Naturg. Mecklenburg 23: 74. 1870. Ditrichum pusillum var. tortile (Schrad.) I. Hag., Kongel. Norske Vidensk., Selsk. Skr. 1910 (1): 50. 1910. Trichostomum tortile Schrad., Bot. Zeitung (Regensburg) 1: 74. 1802.
Plants small, 0.7–1.0 cm high, yellowish green or brown, in loose tufts. Stems erect, simple or sparsely branched. Leaves appressed when dry, erect-patent when moist, lanceolate, 2.0–2.3 mm long, gradually narrowed from an ovate base to a slender acumen; margins reflexed or revolute below, plane above, entire throughout; costa stout, shortly excurrent; cells rectangular, thin-walled, 10–20 µm × 3–5 µm at the shoulder, 13–26 µm × 5–10 µm at the margins, the upper ones shorter. Dioicous. Setae straight, 5.0–7.0 mm long, yellowish brown, sometimes twisted above; capsules erect, oblong-ovoid, symmetric, ca. 2 mm long, smooth when dry; opercula short conic-rostrate; annuli in 2 rows of large and thick-walled cells; peristome teeth linear, ca. 200 µm long, divided nearly to the base, papillose, whitish yellow above, yellowish brown below. Spores 16–18 µm in diameter, yellowish brown, irregularly papillose.