Suffrutescent perennial herbs or shrubs. Leaves petiolate; blades lineolate, usually entire. Inflorescence terminal or axillary, simple or branched dense spikes; bracts larger than calyx, neither ciliate nor spinescent; bracteoles smaller than calyx lobes. Flowers heterostylous, blue, purple, violet or purplish-white; calyx deeply 5-lobed, lobes equal, valvate, almost scarious; corolla tube cylindrical, more than 2 x as long as equal, imbricate lobes, limb patent; stamens 2, inserted at throat, anthers 2-thecous, parallel, emucronate, staminodes 2, small, shortly connate to filaments; ovary with 2 ovules in each locule, style long, somewhat pubescent. Capsules oblong-clavate, with solid stipe-like basal part, septae with retinacula remaining attached to inner wall of mature capsule; seeds 4, mucilaginous pubescent.
Asia-Tropical: Bangladesh (Bangladesh present); India present; Sri Lanka (Sri Lanka present), Burma present, Nepal present, gardens in Latin America cultivated
A genus of about 30 species, distributed mainly in India, Nepal, Sri Lanka, Bangladesh and Burma; 1 species is cultivated in gardens in Latin America and is occasionally found as an escape.