Nearly glabrous annual, with prostrate stems spreading from base, 5-150 mm tall, roots long, spreading and white. Leaves alternate and opposite, scattered, linear or clavate, rolled inwards, margins thickened, dentate, teeth tipped with a minute, bifid mucro. Flowers shortly pedicellate, broadly funnel-shaped, pale blue, ovary (2)3-locular, style constricted below stigma. Capsule hemispherical, with upper part broadly conical.