Long, linear, threadlike leaves are mostly opposite on slender branching stems. Leaf tip tapers to a point. The seeds occur in groups of 2 to 4 forming at the leaf axils and are shaped like horns, hence the name. Found in shallower depths, they can thrive in fresh or brackish waters.
One of the first plants to appear in the Spring, it does best in cool water. When the water warms in June they release seeds and die back. Often the plants will return in the Fall. Seeds can germinate in the same season.
