Perennial, rhizomatous, 10-80 cm long, procumbent and rooting below at the nodes, ascending or floating, glabrous green, rarely with scattered simple hairs. Leaves lyrate-pinnate; lower stalked with 1-5 leaflets; upper sessile, auricled at the base, and with 5-9 leaflets; terminal leaflet suborbicular or broadly cordate; lateral leaflet entire to sinuate-toothed. Leaves and stem remaining green in au¬tumn. Racemes 10-25-flowered, lax, up to 20 cm long in fruits. Flowers c. 4 mm across, white; pedicels up to 10 (-15) mm long in fruit, spreading, horizontal or slightly deflexed. Sepals c. 2 mm long. Petals 4-5 (-6) mm long, c. 2 mm broad. Stamens c. 2:3 mm long. Siliquae oblong, subcylindrical, 10-20 mm long, 2-2.5 mm broad, often slightly upcurved, glabrous, faintly veined, finely headed due to the pressure of seeds on valves; style 0.5-1 mm long with depressed stigma; seeds many, ± biseriate, ovoid, c. 1 mm long with c. 25 polygonal depressions on each face.