Herbs, annual or perennial. Leaves alternate to opposite, simple, sessile, lanceolate to ovate or oblong, acute. Flowers in terminal cymes or thyrses, blue, red, purple or white. Calyx narrow, tubular to campanulate, lobes sharp pointed. Corolla salver-shaped, contorted in bud; tube very slender, lobes flat, spreading. Stamens usually unequal, included. Style slender. Ovary 3-locular, capsule 3- valved; seeds few or 1 in each locule.