Unarmed terrestrial or aquatic herbs. Leaves bipinnate, sensitive to the touch, rachis with or without extrafloral nectaries, pinnae eglandular; Stipules not spinescent. Inflorescences consisting of a pedunculate, solitary, axillary, elliptic glomerule, with bisexual flowers in the distal part, and sterile flower with ± elongated staminodes at the base. Petals 5, free or ± fused at the base. Stamens 10, free, all fertile in the bisexual flowers; Seeds ± flattened, brown, with a hard brown testa with pleurogram.
Asia: present Asia-Tropical: tropics of the Old and New World: present
11 species in the tropics of the Old and New World, 5 in Asia; in Malesia 4 species.
A poorly collected genus. The sterile flowers are different within the heads; the distal ones are larger, with rudimentary anthers at the top of the staminodes.