Description from Flora of China
Herbs twining, annual or biannual. Spikes axillary; rachis long, thick. Bracts minute. Bracteoles and urceolate perianth adnate, ovoid or oblong, opening very little in anthesis, fleshy and enclosing the fruit after flowering. Flowers sessile; perianth segments short, fleshy, blunt, ridged on back, hardly opening at anthesis, not wing-shaped in fruit. Stamens included; filaments inserted near apex of perianth tube, very short, erect in bud; anthers dorsifixed, or versatile. Styles 3; stigmas linear. Utricle globose, fleshy. Embryo spiral; cotyledons large, thin.
Five species: one species endemic to tropical Africa, three endemic to Madagascar, one pantropical; one species (probably introduced) in China.