MARSH CRESS

also called Yellow Cress, any of the 70 plant species of the genus Rorippa of the mustard family (Brassicaceae). Most members of the genus are found in the Northern Hemisphere. The genus has at times been included with the genera Nasturtium and Radicula. Iceland watercress, or marsh yellow cress (R. islandica, sometimes Nasturtium palustre), grows, like others of the genus, in marshy ground. It bears small, four-petaled, yellow flowers in clusters at the top of the flowering spikes. Iceland watercress is annual, but greater yellow cress (R. amphibia) is perennial. The latter is often used in aquariums. Creeping yellow cress, or water rocket (R. sylvestris), is a perennial that grows from a rootstock.