Tall, erect, branched, coarse herb, much variable in hairiness, tomentose or densely woolly, rarely sparsely hairy; stems acutely 4-angled, divaricately branched; leaves ovate, acuminate at apex, subcordate at base, slightly thick, softly pubescent; petioles densely hairy; purple flowers in axillary whorls or verticillasters or in lax, few flowered, branched, axillary, panicled cymes; bracts linear, pubescent or clothed with long stiff hairs; calyx subsessile, tubular, hirsute, equally 5-toothed, teeth lanceolate, acute ciliate, about as long as the tube, enlarging in fruit; corolla pink, sometime yellow, upper lip ciliate, erect, lower lip much longer, spreading, midlobe deeply bifid, pilose, tube subequalling the calyx; stamens-4, exserted, didynamous, filament pubescent at middle, anther cells transverse, parallel; ovary 4-lobed, 4-ovuled, style subequally bifid; nutlets ovoid or oblong, smooth, shining.