Annual, erect dichotomously branched herb; stem 4-angled, thickened at nodes, often covered with white hairs; leaves opposite, obovate-lanceolate, entire or undulate, obtuse, thinly pilose, uppermost leaves sessile, lower subsessile; flowers in sessile or subsessile, usually solitary, terminal, long peduncled, large, globose head; bract ovate, triangular; bractoles deep purple, pink or white, much larger than perianth, distinct dentate-serrate with winged, dorsal crest; perianth lobes- 5, 1- nerved, shorter than staminal tube, yellowish-green, white-woolly out side; stamens-5, filaments slender, united below into a long tube, cleft at the top with 1-celled anther in each, usually without staminodes; ovary subglobose or turbinate, stigmas-2, ovule -1, pendulous; utricle compressed, indehiscent; seeds lenticular, reniform turgid, shiny.