1. Breidleria Loesk. 扁灰藓属 bian hui xian shu
Stud. Morph. Syst. Laubm. 172. 1910. Hypnum subgen. Breidleria (Loesk.) Doignon & Guill., Rev. Bryol. Lichénol. 20: 280. 1951. Hypnum sect. Breidleria (Loesk.) Moenk., Laubm. Eur. 886. 1927.
Plants aquatic or semi-aquatic, robust, large, soft, glossy, in tufts. Stems prostrate or ascending, simple or remotely branched, rarely irregularly branched or in clusters, foliate branches flattened; in stem cross section epidermal cells lax, hyaline, thin-walled. Leaves not in true biseriate arrangement, dorsal leaves of stems and branches shorter, ventral and lateral leaves longer, distinctly falcate-secund, ovate-lanceolate, slenderly acuminate, not or slightly decurrent at base; costae double, short or indistinct; leaf cells linear; alar cells short, thick- or thin-walled. Dioicous or autoicous. Inner perichaetial leaves plicate, filiform at apex. Setae elongate; capsules suberect or horizontal, ellipsoidal or shortly cylindrical, arcuate; opercula conic, rostrate; peristome hypnoid.