n.
Perennial plant ( Nasturtium officinale ) of the mustard family , native to Eurasia and naturalized throughout North America.
It grows submerged, floating on the water, or spread over mud surfaces in cool, flowing streams. White flowers are followed by small, beanlike seedpods. Watercress is often cultivated in tanks for its young shoots, which are used in salads. The delicate, light green, peppery-flavoured leaves are rich in vitamin C. Since watercress grown near cattle and sheep feedlots can become contaminated by feces containing cysts of the liver fluke, agent of the illness fascioliasis (liver rot), regulations specify that commercial watercress beds be protected from such pollution.