Annual herbs, turning black on drying. Leaves opposite or alternate, linear, entire or 3-fid. Bracts and bracteoles both present. Flowers solitary, axillary and/or in a terminal raceme. Calyx 5-lobed, campanulate. Corolla 5-lobed. Stamens 4; anthers 2-thecous. Fruit a capsule. Seeds numerous.
Worldwide: 4-5 species in tropical Africa and India