2. Hydrobryum Endlicher, Gen. Pl. 1375. 1841.
水石衣属 shui shi yi shu
Herbs, perennial. Roots expanded, thalloid, rarely branched. Leaves scale-like, distichous, equitant, sometimes linear or partly linear. Flowers solitary, terminal, shortly pedicellate, enclosed in a spathella before anthesis; spathella longitudinally dehiscent. Tepals (1 or)2(-4), at both sides of filament base. Stamens 2; filaments basally united; anther 2-loculed. Ovary 2-loculed. Stigmas 2. Capsule 2-valved, equal, prominently 5- or 6-ribbed.
Four species: E and S Asia; one species in China.
Lower Taxon