[pnwflowers.com] Habitat, Description: Plant rooted in sediment. Leaves dark green, long, narrow, limp, with ends often floating across water surface. Flowers above water on stem, 2 - 3 female flower heads, each about 1/3 in. across when mature, topped by 1 male round flower head. Female flowers bur like in fruit. Grows in shallow water to 2 ft. deep in ponds and lakes at low to high elevations. Other common bur reeds are S. emersum, with single male flower head separated from others, and S. eurycarpum, with stiff leaves and flower stems arising from water. (link added by Mary Ann Machi)