4. Polytrichum sphaerothecium (Besch.) C. Müll. 球蒴金发藓 qiu shuo jin fa xian
Gen. Musc. Frond. 176. 1900. Pogonatum sphaerothecium Besch., Ann. Sci. Nat., Bot., ser. 7, 17: 353. 1893. Type: Japan.
Polytrichum sphaerothecium var. major Sak., Bot. Mag. (Tokyo) 49: 134. 1935.
Plants small, brownish green, slightly glossy, in dense aggregated tufts. Stems erect, 1–3 cm high. Leaves slightly incurved, usually appressed on stems when dry, erect-patent when moist, 3–6 mm × 1.2–1.5 mm, ovate-lanceolate to oblong-lanceolate, acuminate or cucullate at apex, sheathing indistinct; costa excurrent into a short filiform apex, smooth or a few teeth on back near apex; leaf margins involute, covering ventral lamellae; upper leaf cells quadrate or oblate, 12–15 µm wide, sometimes the length 1–2 times longer than width; median cells rectangular, 18–40 µm × 8–10 µm; basal cells quadrate to narrowly rectangular, bordered by narrow, hyaline cells; ventral lamellae in ca. 30 rows, 6–11 cells high; marginal cells of lamellae pyriform, thick-walled. Dioicous. Male plants similar to the female ones, occasionally with new innovations. Perigonial leaves ca. 3 mm long, with oblong sheathing base. Perichaetial leaves up to 9 mm long, from an ovate sheathing base, suddenly narrowed to a lanceolate lamina. Setae 5–9 mm long, pendulous; capsules nearly spherical, horizontal to cernuous, with distinct discoid apophyses; exothecial cells hexagonal to triangular, without mammillae; opercula with short beaks; peristome teeth often more than 32, triangular, acuminate, ca. 30 µm long, grayish yellow, membrane nearly as long as the peristome teeth. Calyptrae triangular, 3–4 mm long, densely covered with long hairs. Spores spherical, 12–17 µm in diameter, verrucose.