Aquatic Plants are plants that grow in water. Such plants occur in almost every major group of the plant kingdom and are widely distributed throughout the world, inhabiting oceans and brackish lakes as well as freshwater lakes, rivers, and streams. Although most aquatic plants live only in water, some species may also live on land. In these species, however, the land-dwelling form often differs in appearance from the aquatic form. The aquatic arrowhead, for example, has limp, ribbonlike leaves, while the terrestrial form bears the stiff, arrowhead-shaped leaves from which the plant's name is derived. Major Groups Aquatic plants are generally divided into four major groups. Plants of the first group float freely on or below the surface of the water and have no connection with the soil. Among the best known of these plants is the salvinia, a small ornamental plant with whorls of oval leaves that are covered with stiff, bristly hairs on their upper surface. The salvinia is grown