6. Plagiopus Brid. 平珠藓属 ping zhu xian shu
Bryol. Univ. 1: 596. 1826. Bartramia subgen. Plagiopus (Brid.) Kindb., Eur. N. Amer. Bryin. 2: 322. 1897.
Plants medium-sized to rather large, slender, dark green or brownish, dull, in dense tufts. Stems erect or ascending, sparsely branched or densely branched at top of stems, with dense rhizoids at base; triangular in cross section, central strand weakly developed. Leaves erect, curved or twisted when dry, erect-spreading or squarrose when moist, narrowly lanceolate, with a long-acuminate and more or less keeled apex, plicate, not sheathing at base; margins recurved near base, sharply double-toothed above; costae percurrent or shortly excurrent, dentate at back; leaf cells unistratose except at base and basal margins; median cells quadrate or rectangular, smooth, thick-walled, not porose; basal cells longer; basal juxtacostal cells elongate, thin-walled; basal marginal cells shortly rectangular. Synoicous. Setae elongate, straight, reddish purple; capsules erect or slightly inclined, spherical, curved, brownish, furrowed when dry; opercula small, shortly conic; peristome double; exostome teeth smooth; endostome segments almost as long as the teeth, pale yellowish, perforate; cilia single or absent. Calyptrae cucullate, smooth. Spores kidney-shaped, mostly coarsely papillose.