White flowers, 4-petalled, on erect flowering stems. Slender fruit with single row
of seeds. Leaves pinnate, the leaflets usually un-lobed. Stems and leaves turn purple-brown in autumn. Slightly fleshy stems, creeping, rooting. Hairless plant.
Frequent in and beside shallow freshwater. Streams, ponds, marshes. Found in similar locations to Water-cress, R. nasturtium-aquaticum.
Hybrids can occur.