Han Cai

Nasturtium officinale, watercress, is a perennial aquatic to semi-aquatic herb of the Brassicaceae family, native to Europe and western Asia and now naturalized globally in cool flowing waters. The plant forms creeping, hollow, succulent stems that float or trail along stream margins, rooting freely at the nodes. Leaves are pinnately compound with three to nine glossy, dark-green, ovate to rounded leaflets, the terminal leaflet typically the largest. Small four-petalled white flowers are borne in terminal racemes during spring and summer, followed by slender curved siliques containing two rows of small seeds. The whole plant has a sharp, pungent, peppery taste characteristic of mustard-family glucosinolates, and is harvested year-round from clean running water for both culinary and medicinal use.