Nasturtium officinale, known as watercress, is a rapidly growing, aquatic or semi-aquatic, perennial plant native to Europe and Asia, and one of the oldest known leaf vegetables consumed by humans.
It is a member of the family Brassicaceae; watercress and its relatives garden cress, mustard, radish, and wasabi are all noteworthy for their piquant flavors. The hollow stems of watercress will float; the leaf structure is pinnately compound.
Small, white and green flowers are produced in clusters and are frequently visited by insects, especially hoverflies such as Eristalis flies.
Watercress can grow to a height of 50 to 120 centimetres (1 1⁄2–4 ft). Like many plants in this family, the foliage of watercress becomes bitter when the plants begin producing flowers.