Watercress, with the botanical name Nasturtium officinale, 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.
Found in stream in SE Idaho.