Perennial, erect herb, attaining height about 50 cm; roots tuberous, fleshy; stem 4- angled; leaves opposite, elliptic-obovate, obtuse at apex, entire, subentire or undulate margins, sparingly hairy; shortly petiolate; flowers in axillary as well as terminal cymes; bracteoles linear-subulate; calyx long, linear, glandular; corolla blue-violet, 4-5 cm long, hairy outside, lobes subequal, obtuse, spreading, twisted to left in bud; stamens 4, cells oblong, didynamous, anthers 2- celled, subequal, muticous, filament glabrous, slender; staminodes linear; ovary 2-celled, ovules 2-10 in each locule, style slender, stigma simple; capsules 2.5-3.5 cm long, cylindric, minutely beaked above; seeds 20-40, orbicular, compressed, hairy.