4. Zygodon viridissimus (Dicks.) Brid. 绿色变齿藓 lu se bian chi xian
Bryol. Univ. 1: 592. 1826. Amphoridium viridissimum (Dicks.) De Not., Atti Reale Univ. Genova, 1: 277. 1869. Gymnostomum viridissimum (Dicks.) Sm., Engl. Bot., 22: 1583. 1806. Dicranum viridissimum (Dicks.) Turner, Muscol. Hibern. Spic. 71. 1804. Bryum viridissimum Dicks., Fasc. Pl. Crypt. Brit. 4: 9. 1801. Type: Europe.
Plants small to medium-sized, light green to dark green, often in loose mats. Stems erect, to 1.5 cm high, dichotomously branched, with few rhizoids at the base. Leaves twisted when dry, erect-spreading when moist, oblong-lanceolate, 1–2 mm long, acuminate, ending with 1–2 cells at the tip, often recurved above, keeled below; margins plane and entire; costae subpercurrent, often papillose on the back; upper leaf cells rounded to rounded-quadrate, 7–10 µm wide, thick-walled, densely papillose; lower and basal leaf cells rectangular, smooth, thin-walled, gradually becoming shorter toward margin. Gemmae axillary, composed of 5–10 cells of fusiform, ellipsoid or subclavate forms. Dioicous. Setae 4–7 mm long; capsules narrowly pyriform, furrowed; opercula obliquely rostrate; exothecial cells slightly differentiated in longitudinal bands; peristome absent, only consisting of a low, papillose basal membrane. Calyptrae cucullate, not plicate, naked. Spores 11–14 µm in diameter, papillose.