Shrubs, climbing, or small trees. Leaves opposite. Inflorescences terminal or axillary irregular thyrses. Calyx minutely 4-dentate in flower. Corolla nearly funnelform; lobes 4, unequal, spreading. Stamens 4, inserted at corolla throat; anthers ovate, dehiscing by longitudinal slits. Ovary 2-locular; ovules 2 per locule. Style exserted; stigma 2-cleft. Fruiting calyx tube greatly inflated, bladderlike, translucently membranous, with reticulate veins, teeth remaining minute. Fruit a globose schizocarp.

About six species: chiefly in SE Asia, one species in China.