Description from Flora of China
Herbs erect or prostrate, many branched, most parts usually streaked with white raphids. Leaves opposite or pseudoverticillate, linear to narrowly lanceolate. Inflorescences terminal, sometimes apparently axillary, sessile or pedunculate, dichasial, dense and umbel-like or lax; bracts and bracteoles minute and scarious, sometimes obsolete. Flowers usually bisexual. Tepals 5, persistent, free, pale green to white, often flushed pink to red, rarely yellowish, herbaceous with membranous margin. Stamens 5-20, free; filaments flattened, lanceolate. Carpels (3-)5(-15), seemingly free but basally connate, each with one ovule. Fruit a cluster of reniform mericarps, usually tuberculate to ± spiny, often also smooth on same individual, or winged (not in Flora area). Seeds with curved embryo.
About seven species: five restricted to Africa, one widely distributed in tropical and subtropical Africa and Asia, one restricted to Asia; two species in China.