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 and radishâall noteworthy for their peppery, tangy, zesty, piquant flavor.