Herbs or shrubs, most parts with white bladder cells. Stems ascending, rarely creeping. Leaves opposite; petiole broadening basally forming a papery sheath clasping stem; leaf blade cylindric to obovate, fleshy. Inflorescences cymose or flowers solitary. Flowers bisexual, sessile or pedicellate. Perigone 5-parted, lobes inside often pink to purple, rarely white, oblong, ending in protracted spurs. Stamens 5 to numerous, free or inserted in perigone tube. Perigynous, ovary free from perigone tube, 3-5-loculed, ovules numerous per locule; stigmas 3-5, linear. Capsule ellipsoid, thinly walled, membranous, circumscissile. Seeds many per locule, enveloped by a black smooth aril.

About 17 species: tropical and subtropical regions; one species in China.