Annual herbs, hygrophilous, glabrous. Stem ± quadrangular. Inflorescence axillary, solitary or spicate, in almost every axil. Flowers 4-5-merous, sessile, 2-bracteolate; bracteoles ± equalling the flower. Hypanthium campanulate or tubular-campanulate, membranous in fruit. Epicalyx present or absent. Petals persistent. Ovary oblong or 3-angled, 2-3(-4)-locular, style short. Capsule equalling the hypanthium, 2-3 (-4)-valved, faintly horizontally striate, placenta clavate. Seeds elongated or roundish.