Erect, nearly glabrous undershrub; stem erect, swollen above the nodes; leaves elliptic or ovate lanceolate, tapering towards both ends, acuminate at apex, subentire, glabrous; flowers in terminal and axillary, more or less interrupted spikes; bracts white with green veins, hairy, large, obovate, mucronate or shortly apiculate, glandular pubescent, imbricate; bracteoles linear, pubescent, ciliate; calyx white, pubescent, lobes-5, lanceolate; corolla violet-blue, 2-4 cm long, lobes oblong-obovate, tube linear, slender; stamens-2, fertile, 2 rudimentary or absent, glabrous, anthers narrowly oblong, 2-celled, muticous, exserted or subincluded; ovary 2-locular, glabrous, 4-ovuled, style long, sparingly hairy, stigma simple, linear; capsules cylindric, clavate, glabrous, 4-seeded; seeds discoid, compressed, brown, finely hairy.