Leaves alternate, petiolate, serrate, crenate or entire; cystoliths punctiform; stipules free, lateral
Annual herbs, monoecious or (by abortion) dioecious
Achene slightly winged along one side, other side rounded, frequently 2 ovaries or achenes join along the rounded side to form a double fruit, which is much larger than two single fruits, both seeds developing in this case
Inflorescences usually bisexual, axillary, sessile, bracted, bracts free, not prominent, usually shorter than the flowers
Flowers: ♂ with a boat-shaped, sometimes almost bract-like perianth with erect tip and slightly fused cylindrical base, with 1 stamen, without rudimentary ovary; ♀ without perianth, ovary erect, with a subcapitate or shortly linear style
Achene with a narrow, slightly unilateral wing.
Leaves alternate, petiolate, serrate, dentate or entire; stipules lateral, free.
Slender annual herbs, monoecious or dioecious by abortion.
Male flowers few together, sessile; perianth boat-shaped; stamen single, inflexed; rudimentary ovary absent.
Female flowers sessile; perianth and staminodes absent; ovary erect, stigma sessile, filiform.