This semi-aquatic perennial has procumbent hollow stems that float on water and may become erect with age. It has divided mid green leaves and white petalled saucer-shaped flowers appear in a small raceme during spring. 

Hardiness zones 6 to 10 

Nasturtium officinale is naturally found in Europe growing along water courses or at headwaters in moderately well drained to boggy wet fertile soils in an open sunny position and is frost and drought tender. 

Watercress is grown for its editable foliage and is used in cooking and for herbal remedies. It is planted in ponds or tubs of water or grown commercially hydroponically. Under ideal conditions it has become a weed that infests watercourses and is controlled by physical removal of the plant and the roots. It tolerates a wide range of climate zones and establishes in one season. ID 838

Nasturtium (nas-TUR-tee-um) officinale (o-fi-ki-NAH-lee)

Brassicaceae (brass-ih-KAY-see-ee)
(Cruciferae)
Cabbage, Mustard, Rapeseed, Turnip and Woad Family