4. Plagiobryum zierii (Hedw.) Lindb. 平蒴藓 ping shuo xian
Öfvers. Förh. Kongl. Svenska Vetensk.-Akad. 19: 606. 1863. Bryum zierii Dicks. ex Hedw., Sp. Musc. Frond. 182. 1801. Type: Scotland.
Plants small, ca. 8 mm high, grayish or grayish green, in tufts. Stems simple or branched at base. Leaves imbricate, ovate-cordate to cordate, clearly keeled; margins plane, entire, borders not differentiated; costae excurrent, ending in bent awns; median leaf cells lax, hexagonal to rectangular, thin-walled; upper cells hyaline; basal cells quadrate or shortly rectangular. Setae ca. 8 mm long, slightly curved; capsules long-club-shaped, horizontal to pendulous, asymmetric, neck shorter than urn, shrunk when dry; mouth narrowed; opercula conic; peristome double; endostome segments slightly longer than the teeth. Spores spherical or ellipsoidal, 21–31 µm in diameter, yellowish brown, papillose.