Aquatic plant forming colonies by underwater horizontal stems (rhizomes). Mostly unbranched stems are round and often rusty-spotted. Leaves are often underwater but may float. Whorls of tiny greenish flowers grow on spikes that are held above the water.
Leaf stems distinctly paler near their tip; floating leaf blade rounded to 5 inches long, stem to 35 inches long; submerged leaves narrow thread-like or ribbon-like, to 1/2 inch wide; stipular sheaths of submersed leaves from base of leaf blade.
Habitat
Shallow, still, slow-moving, brackish (saltier than fresh water) or fresh water in lakes, ponds, bogs, marshes, lagoons and streams.
Flower Characteristics
Dense, cylindrical flower spikes are 2 to 4 inches long, and grow from the axils (between the leaf and stem) of the floating leaves. 6 to 10+ whorls of flowers grow along the flower spike. Each greenish flower has 4 leaf-like sepals and no petals.
Leaf and Stem Characteristics
Floating leaves are leathery, 17 to 37 veined, rounded, often heart-shaped at the base. The leaf stalk is much longer than the leaf, often bent where it meets the blade and noticeably pale just below the blade. Underwater leaves are clear, rigid, narrow.
Fruit and Seed Characteristics
Fruit is plump, irregularly oval-shaped, rounded on the back, wrinkled and often with no ridges on its surface. It is 1/8 to 1/4 inch long with a short (<1/16 inch long) projection (beak) on its tip which may be upright or curve backwards.
The seed is about 1/8 inch long, oblong to circular in shape with a loose, shiny skin on its surface.