Annual herbs, mostly woody at base, sometimes creeping. Leaves sessile or petiolate, margin slightly revolute, apex acute or acuminate; venation pinnate. Inflorescences axillary and/or terminal, spikes or racemes, sometimes composed of 2 or 3 spikes or racemes (rarely a solitary flower). Flowers sessile or pedicellate, opposite, decussate or verticillate, 4-merous; calyx tubular to campanulate, calyx lobes 4, imbricate, (very) weakly keeled, margin membranous, apex (long-)acuminate; corolla salver-shaped, 4-lobed, tube with conspicuous longitudinal veins, persistent around fruit; stamens 4, filaments filiform, inserted on corolla tube with a flat membranous structure, anthers sagittate, introrse; pollen in tetrads; stigma 2-lobed. Fruit a capsule with persistent calyx and corolla tube; seeds triangular with 3 hollow sides, sometimes globose, foveolate.
Guianas present, Neotropics present
5 species in the Neotropics, growing in savannas, open places or disturbed areas; 4 species in the Guianas.