Annual herbs, monoecious. Staminate flowers in clusters, these arranged in terminal spiciform inflorescences; perianth of staminate flowers 3-5-lobed; stamens 2-5; pistillate flowers mostly solitary, bibracteolate; bracteoles small, accrescent in fruit; perianth of pistillate flowers of 3-4 segments, stigmas 2. Fruit enclosed by the shortly winged perianth; pericarp adherent; seeds vertical; embryo horseshoe-shaped; radicle descending. Zn = 18. Six spp., C Asia, Himalaya, SW China.