Watercress (Nasturtium officinale = Rorippa nasturtium-officinale) is a creeping-emergent plant which grows floating or prostrate in mud, with stems rooting at nodes, up to 2m long, usually in shallow water in springs or streams in fresh and oligohaline conditions. It has clusters of small 4-petaled white flowers. Watercress has a wide native distribution in Eurasia, North Africa, and East Asia. It is widely harvested and sometimes cultivated as a vegetable. It was probably introduced to eastern North America very early, in dry ballast, or as a crop. It was collected in Rhode Island in 1831, Portland, Oregon in 1881, and in the Sacramento-San Joaquin Delta by1891. It has been widely introduced around the world, including South America, tropical Africa, Australia, and New Zealand.