Erect - suberect, annual - perennial, solitary or branched or procumbent herb. Stem quadrangular, leafy or slender. Basal leaves rosulate, persistent or disappearing at fruiting. Inflorescence cymose or spicate cyme; cyme lax or compact, sometimes capituliform. Flowers tetra-pentamerous, variously coloured: white, pink, purple, purplish, blue, yellow, tubular, sessile-pedicellate. Calyx narrow, parted nearly to the base or not, lobes acute - acuminate, keeled or angular. Corolla tubular, subinfundibular, funnel shaped, tube more than the length of lobes. Stamens inserted near the sinuses of corolla lobes; anthers narrow, basifixed, spirally twisted after anthesis. Ovary 1-celled, style bifid at apex, stigmas capitate. Capsule oblong, fusiform or ovate. Seeds numerous, minute, reddish brown-black, reticulate.