Arrowhead (Sagittaria), a genus of petaloid monocotyledons of the order Alismaceæ, distinguished by unisexual flowers, having three herbaceous sepals and three coloured petals, with numerous stamens and carpels, the latter separate. They are aquatic plants, natives of very different climates, from the tropics to the cold regions of the world.—The Common Arrowhead (S. sagittifolia) is a beautiful aquatic, a native of England, with arrow-shaped leaves which rise above the surface of the water. It is one of those plants which have enjoyed an undeserved reputation as cures for hydrophobia. The starchy cornus have sometimes been used for food, but have an acrid unpleasant taste. S. sinensis has long been cultivated in China and Japan; and S. obtusifolia (N. America) is also used as food. Several species and many varieties of this genus are found in North American waters.