21. Phascum Hedw. 球藓属 qiu xian shu
Sp. Musc. Frond. 19. 1801.
Plants very small, green or yellowish green, in loose tufts. Stems erect, simple or branched; central strand absent. Leaves crowded, rosulate, larger toward the stem tips, ovate to obovate or oblong-lanceolate, acute to acuminate, usually piliferous at the apex; margins entire, plane or weakly revolute in the lower half; costa slender, short- to long-excurrent, ending with a hyaline awn, in cross section only dorsal stereid band present; upper leaf cells rounded quadrate, thin-walled, usually with several C-shaped papillae, rarely smooth; basal cells enlarged, rectangular, smooth. Autoicous. Perichaetial leaves similar to stem leaves. Setae very short; capsules immersed to emergent, globose, bluntly apiculate; opercula not developed; peristome none. Calyptrae cucullate, smooth. Spores spherical, brownish, densely papillose to tuberculate.