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.