Description from Flora of China
Fimbripetalum (Turczaninow) Ikonnikov; Mesostemma Vvedensky.
Herbs annual, biennial, or perennial. Roots or rhizomes filiform and slender, roots sometimes robust, fleshy. Stems erect, ascending, or prostrate. Leaves compressed, variously shaped, rarely needlelike; stipules absent. Flowers terminal, seldom only axillary, in cymes or solitary, small; bracts immediately subtending calyx absent. Sepals (4 or)5. Petals (4 or)5, white, rarely green, usually 2-cleft nearly to base, rarely retuse or multilobed, sometimes absent. Stamens 2--5 or (6--)10. Ovary 1-loculed, rarely 3-loculed when young; ovules numerous, rarely several and only 1 or 2 mature; styles (2 or)3(or 4). Capsule orbicular or ovoid, opening by valves (1 or)2 × number of styles. Seeds (1 to) numerous, reniform, slightly compressed, tuberculate or smooth; embryo curved.
About 190 species: mainly in temperate and cold regions; 64 species (28 endemic) in China.
(Authors: Chen Shilong; Richard K. Rabeler)