Erect, perennial, diffused undershrub; stem 4 angled; leaves petiolate, opposite, elliptic to oblong, tapering towards both ends, acuminate, entire, yellow, hairy beneath; flowers in short, subsessile, axillary and terminal, often in compound, capitate, dense spikes; bracts absent; bracteoles linear, acute, pubescent, membranous, prominently veined; calyx divided nearly up to base, two outer segments large, ovate-oblong, soft, bristle-tipped or sub spinescent, two inner narrower lanceolate, ciliate; corolla purple or white, pubescent outside, tube funnel-shaped in the upper half, lobes-5, subequal, ovate, imbricate in bud; stamens 4, 2 fertile, 2-rudimentary; anthers 2-celled, oblong; disk large, cupular; ovary 2-locular, each 2-ovuled; style long; stigma 2-fid or subentire; capsule 1-2 cm, ellipsoid, 4 seeded; seeds orbicular, compressed, brown, covered with silky hairs.