Description from Flora of China
Herbs, mostly annual. Stem branches opposite, rarely 3 in a whorl apically. Leaves entire or dissected. Flowers in terminal racemes or panicles, bracteate. Bracts foliaceous. Calyx campanulate, 5-lobed. Corolla lobes 5, spreading; lower lobes 2, inner in bud. Stamens 4, didynamous, included; anther locules 2 per stamen, 1 fertile, 1 reduced and empty. Stigma subligulate. Capsule ovoid to oblong, apex rounded or compressed, emarginate or deeply concave, loculicidal; valves not divided or shallowly lobed, separating from placental axis. Seeds numerous; seed coat loose.
About 40 species: Africa, tropical to subtropical E Asia; two species in China.
Sopubia stricta G. Don has been reported from the coast of Guangdong, but we have not seen Chinese specimens.