Description from Flora of China
Shrubs deciduous. Branches spreading; branchlets angled, glabrous; buds ± ovoid, with several imbricate scales, glabrous or subglabrous, apex obtuse or acute. Leaves petiolate; stipules absent or small and caducous; leaf blade simple, margin entire or serrate. Inflorescence a terminal raceme. Flowers rather large, more than 2 cm in diam. Hypanthium shallowly campanulate. Sepals 5, very short and broad. Petals 5, imbricate, white, oblong to broadly obovate, base attenuate into a claw. Stamens 15–30; filaments borne on margin of large disk, short. Carpels 5, connate; ovary superior, deeply furrowed, 5-loculed; styles free. Fruit a capsule, obconic, 5-angled, dehiscent along both sutures. Seeds 1 or 2, oblate, winged.
About four species: C and E Asia; three species (two endemic) in China.
(Authors: Gu Cuizhi (Ku Tsue-chih); Crinan Alexander)