Watercress

Watercress is an aquatic plant species with the botanical name Nasturtium officinale. This should not be confused with the quite different group of plants with the common name of nasturtium, botanical name Tropaeolum.

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 currently a member of the family Brassicaceae, botanically related to garden cress, mustard, radish and wasabi—all noteworthy for their piquant flavor.

The hollow stems of watercress are floating, and the leaves are pinnately compound. Small, white and green flowers are produced in clusters and are frequently visited by insects, especially hoverflies such as Eristalis flies.

Taxonomy

Watercress is also listed in some sources as belonging to the genus Rorippa, although molecular evidence shows the aquatic species with hollow stems are more closely related to Cardamine than Rorippa. Despite the Latin name, watercress is not particularly closely related to the flowers popularly known as nasturtiums (Tropaeolum majus); T. majus belongs to the family Tropaeolaceae, a sister taxon to the Brassicaceae within the order Brassicales.