Fanwort is an invasive plant species that originates in the Southeast United States and South America. An invasive plant has the ability to thrive and spread aggressively outside its native range. This is harmful to the local ecosystem and has the potential to greatly reduce the natural biodiversity of an area by outcompeting native species. Fanwort grows completely submersed under the surface of the water, with stems up to 2 meters in length. This plant species has dissected, opposite, fan-like leaves that measure 2 to 5 centimeters, and are made up of forked leaflets attached to the stem by a petiole. Floating leaves 6 to 20 mm wide are oblong and produced on flower shoots. It has small, solitary flowers that are white to pinkish, with flask shaped fruits. Fanwort reproduces via seeds and fragmentation. It can easily be confused with watermilfoils (Myriophyllum spp.), white water crowfoot (Ranunculus longirostris), and water marigold (Megalodonta beckii).
Connecticut's Invasive Aquatic and Wetland Plants Identification Guide, Bulletin 1027, Invasive Aquatic Plant Program, The Connecticut Agricultural Experimentation Station
Invasive Plant Species, National Agricultural Library, United States Department of Agriculture