Family: Cabombaceae, Water-shield view all from this family
Description A rooted aquatic plant with both submersed and floating leaves that is native to the southeastern United States but considered an invasive weed in the Northeast and Northwest.
Flowers: on water surface at tips of short stalks; 3 petals, 3 sepals; usually white, tinged purple; to 1/2" (1.2 cm) wide.
Leaves: submersed leaves to 2" (5 cm) wide; opposite; fan-shaped; divided into numerous small, almost threadlike segments. Floating leaves small, inconspicuous.
Habitat Ponds, lakes, slow streams and rivers, marshes, reservoirs, and other bodies of water.
Range Native to the Southeast, from Virginia, southern Illinois and Kansas south to Florida and Texas. Introduced north to New Hampshire, New York, and Michigan, and in Washington and Oregon.
Discussion Fanwort is a weedy plant even in its native range, where it can grow quite densely, crowding out other aquatic plants. In the Northeast and Northwest it is considered a noxious or invasive pest. It sprouts vegetatively, which means that parts of the plant that break off grow into new plants. It is a popular aquarium plant, and the dumping of aquarium water may hasten its spread into areas where it is not native.