Annual or perennial herbs, usually with brittle stem and watery juice, erect to sprawling or straggling, mostly glabrous. Leaves usually alternate, much divided without jointed segments. Inflorescence a raceme or spike, rarely 1(or 2-3)-flowered, terminal or leaf-opposed. Flowers small, bisexual, usually zygomorhic, hypogynous, generally pedicellate and bracteate. Sepals 2, small, scale-like, caducous. Petals 4, in two dissimilar whorls, 2 outer longer and larger, one or both spurred or saccate, ± connivent; 2 inner smaller, narrower, and often coherent at tips. Stamens 2 (apparently 6 in 2 bundles), tripartite, the central branch bearing a dithecous anther, the lateral branches bearing monothecous stamens. Ovary 1-celled, with 2 parietal placenta, each bearing 1-many anatropous ovules; style simple, long or short with obtuse or lobed stigma. Fruit a 2-valved capsule or a nutlet. Seeds with minute embryo and copious endosperm.