Description from Flora of China
Cardaminum Moench, nom. rej.
Herbs perennial, aquatic, rhizomatous. Trichomes absent or simple. Stems prostrate or decumbent, erect in emergent plants, rooting at proximal nodes. Leaves all cauline, pinnately compound, often simple in deeply submersed plants; petiole sometimes auriculate at base; lateral leaflets 1-6(-12) pairs, petiolulate or sessile, entire, repand, or rarely dentate. Racemes many flowered, ebracteate. Fruiting pedicels usually divaricate. Sepals ovate or oblong, erect or ascending, glabrous, base of lateral pair subsaccate or not saccate. Petals white or rarely pink, longer than sepals; blade obovate or narrowly spatulate, apex obtuse; claw absent. Stamens 6, erect, tetradynamous; filaments base not dilated; anthers oblong, obtuse at apex. Median glands absent; lateral glands 2, annular or semiannular. Ovules 25-50 per ovary. Fruit dehiscent siliques, linear or rarely narrowly oblong, terete, sessile; valves obscurely veined, glabrous, smooth or slightly torulose; replum rounded; septum complete; style obsolete or to 2 mm; stigma capitate, entire. Seeds uniseriate or biseriate, wingless, oblong or ovoid, plump; seed coat minutely to coarsely reticulate, not mucilaginous when wetted; cotyledons accumbent.
Five species: one in NW Africa (Morocco), two in Asia and Europe, and two in North America (N Mexico and United States); one species (introduced) in China.