Annuals, biennials, or perennials; (usually aquatic or of mesic habitats, rhizomatous, sometimes with caudex); not scapose; glabrous or pubescent. Stems erect or prostrate, unbranched or branched. Leaves basal and/or cauline; petiolate or sessile; basal (usually withered early), rosulate or not, petiolate, blade margins entire, dentate, sinuate, lyrate, pectinate, or 1-3-pinnatisect; cauline petiolate or sessile, blade (base cuneate, attenuate, auriculate, or sagittate), margins entire, dentate, pinnatifid, or pinnatisect. Racemes slightly to considerably elongated in fruit. Fruiting pedicels erect, suberect, ascending, horizontal, reflexed, or divaricate, usually slender. Flowers: sepals (rarely persistent), erect or spreading, ovate or oblong, lateral pair not or, rarely, saccate basally, (margins often membranous); petals (rarely vestigial or absent), often yellow, sometimes white or pink, usually obovate, spatulate, oblong, or oblanceolate, rarely linear, claw undifferentiated or not from blade, (often shorter than sepals, apex obtuse or emarginate); stamens usually tetradynamous, rarely 4 and equal; anthers usually ovate or oblong, rarely linear, (apex usually obtuse, rarely apiculate); nectar glands confluent, often subtending bases of stamens, median present. Fruits siliques or silicles, usually sessile, rarely shortly stipitate, linear, oblong, ovoid, ellipsoid, pyriform, subglobose, or globose, smooth or torulose, terete or slightly latiseptate; valves (3-6 in R. barbareifolia) papery or leathery, each obscurely veined, glabrous or pubescent; replum (visible), rounded; septum usually complete, rarely perforate; ovules [10-]18-242[-300] per ovary; style obsolete or distinct; stigma capitate, (rarely slightly 2-lobed). Seeds usually biseriate, rarely uniseriate, plump, not or, rarely, winged, oblong, ovoid, ovate, orbicular, cordiform, subglobose, or globose; seed coat (reticulate, colliculate, rugose, tuberculate, or foveolate), mucilaginous or not when wetted; cotyledons accumbent.