Description from Flora of China
Herbs annual or perennial. Stems straggling, caespitose, ascending, or erect, slender. Leaves sessile or shortly petiolate, oblong, obovate, or ovate-lanceolate to linear; stipules absent. Flowers solitary or in lax, few-flowered cymes; bracts immediately subtending calyx absent. Sepals 4 or 5. Petals 4 or 5, white, margin entire. Stamens (5 or 8) or 10. Ovary 1-loculed; ovules numerous; styles (2 or)3. Capsule ovoid, (4 or)6-toothed. Seeds few, reddish black, smooth, lucid, with a membranous strophiole; embryo curved.
About 25 species: N temperate regions; three species in China.
(Authors: Lu Dequan; Richard K. Rabeler)