Annual or perennial herbs, rarely woody plants. Leaves alternate, simple or compound, partly arranged in basal rosettes. Stipules wanting. Inflorescence consisting of racemes. Bracts usually wanting. Flowers hermaphrodite, actinomorphic. Sepals 4, deciduous or rarely persistent, the outer 2 median, the inner 2 lateral and often saccate at the base. Petals 4, cruciate, sometimes rudimentary or wanting, usually clawed. Stamens 6, tetradynamous (2 stamens of the outer series smaller than the 4 of the inner series); filaments sometimes winged or provided with scale-like appendages; anthers cordate or sagittate at the base, sometimes with elongate connective. Nectar glands attached to the receptacle near the bases of the filaments. Ovary superior, bi-locular by a false septum; style simple or rarely wanting; stigma discoid or more or less 2-lobed. Ovules numerous, anatropous or campylotropous, on 2 parietal placentas. Fruit a siliqua or silicle, usually 2-locular, bivalved or rarely indehiscent. Seeds attached to both sides of the septum. Embryo large, the cotyledons incumbent, accumbent or conduplicate. Endosperm wanting. About 3000 species in 350 genera, widely distributed, especially in the temperate and cold regions of the northern hemisphere.