Perennial hydrophytes or marsh herbs with acrid juice. Leaves upright, linear-lanceolate to ovate. Inflorescence a pyramidal panicle with verticillate branches and flowers. Flowers bisexual, white or pink, bracteate. Thalamus flat, rarely convex. Sepals 3, persistent, appressed in fruit. Petals 3, larger than sepals. Stamens twice as many as petals, in a single whorl and antipetalous pairs, filaments coherent at the base to form nectary, anthers semi-versatile. Carpels many, arranged in a verticil; ovaries unilocular with single basal anatropous ovule; style ventral, erect or curved, stigma papillate. Achenes laterally much compressed, ventrally somewhat beaked near apex, ridged outside. Seeds erect.