This peppery – tasting aquatic plant (Nasturtium officinalis), which grows in the meandering streams, is native to Europe and Asia and is related to mustard and radish. It has hollow stems that enable it to float, scalloped bright-green leaves, and clusters of small white flowers. Greeks and Romans used it to treat respiratory ailments and to make a healthful spring tonic. It is now used to regulate cholesterol and blood pressure, support the heart, and increase bone strength, fight off infections, maintain connective tissue, and prevent iron deficiency. It reduces free radical damage to DNA and displays anticancer properties. Watercress is rich in vitamin K, vitamin A, vitamin C, riboflavin , vitamin B6, and calcium.