Herbs annual. Leaves alternate, sessile, complanate, herbaceous. Flowers axillary, solitary or forming short spikes, bisexual and female (plants polygamous), without bractlets. Perianth 4- or 5-lobed, membranous, remaining unchanged in fruit; segments without appendages. Stamens 4 or 5, exserted; filaments filiform; anthers oblong, minutely appendiculate. Ovary compressed, obovate; style short; stigmas 2, filiform. Utricle not adnate to perianth. Seed vertical; embryo horseshoe-shaped; radicle inferior.