Annual or perennial herbs. Stems 4-ridged. Leaves well-developed. Flowers 4-5-merous in lax few-many-flowered cymes, rarely solitary. Calyx 4-5-lobed, tube very short. Corolla 4-5-lobed with a very short tube, lobes with 1-2 basal glandular nectaries within. Stamens 4-5, anthers without glands (in ours). Ovary ellipsoid, 1-locular. Stigma 2-lobed. Capsule septicidally 2-valved. Seeds numerous.
Worldwide: 50 species in northern temperate zones, Africa and Malesia