8. Pireella Cardot 小蕨藓属 xiao jue xian shu
Rev. Bryol. 40: 17. 1913.
Plants slender, elongate, yellowish green, slightly glossy, in loose mats. Primary stems prostrate, with numerous rhizoids; secondary stems ascending or dendroid, simple below, with closely appressed stipe leaves, irregularly to pinnately branched above, with short branches in almost equal length, densely foliate. Stipe leaves cordate at the base, shortly acuminate at the apex; margins plane, entire, indistinctly denticulate near the apex; ecostate. Leaves of secondary stems and branches erect-spreading, ovate, oblong to ovate-lanceolate, acute to acuminate at the apex; margins plane, entire or denticulate above; costae single, subpercurrent to shortly excurrent; leaf cells oval to rhomboidal to linear, often thick-walled, smooth or sometimes prorate; alar cells not or weakly differentiated. Gemmae often present, hyaline, clavate or almost cylindrical. Dioicous. Inner perichaetial leaves erect, ovate-lanceolate or elongate-lanceolate, with a long acuminate, often twisted apex; margins entire; costae weak. Setae slender, short to elongate, smooth or papillose above, reddish brown; capsules often exserted, erect, oblong-ovoid, small at the mouth; exothecial cells thick-walled; opercula conic, long rostrate; peristome double; exostome teeth pale yellow, rarely red, triangularly lanceolate; endostome segments attached to the teeth, consisting of a thin membrane. Calyptrae cucullate, often sparsely hairy, rarely smooth. Spores spherical or ellipsoidal, large, green, smooth or finely papillose.