Description: Stems rise at intervals from slender roots. Fanwort has two distinct leaf types. Underwater leaves are finely divided, widely branched, and held apart from the stem on slender leaf stems, and looks like tiny fans with handles. The leaves are strictly arranged in opposite pairs along the main stem. The orderly formation of leaves and stems gives the plant a tubular appearance underwater. Plants range in color from grass green to olive green to reddish. Small white flowers (1 cm in diameter) develop among the floating leaves. Habitat: Fanwort is found in the underwater and floating-leaved plant communities, growing in a variety of substrates including sand, mud and gravel. It thrives in stagnant or slow moving waters of lakes, pond and streams in depths of up to 2.5 meters. Large mats of drifting pieces may occur.
Annual Cycle: Fanwort is an water perennial that grows primarily from stem pieces and root expansion. In the spring, new growth rises from buried roots and overwintering stem pieces. Plants grow rapidly to the surface, often forming thick mats. Flowers are produced from May to September. Although fanwort is self-breeding, seed germination in areas beyond its natural range does not appear to be significant. Both the roots and stems are easily broken as the season progresses, helping vegetative spread to new areas.
Origin and U.S. Range: Fanwort is native to South America. The previously held belief that this plant is also native to some parts of the southeastern United States is now under debate. It is not native to New England. An attractive plant, fanwort has long been popular in the aquarium trade. Release from aquaria into the environment is considered to be one of the ways this plant has spread beyond its natural range. Fanwort occurs, and is considered invasive, in many parts of the United States including the nearby states of New Hampshire, Massachusetts, New York, and Rhode Island.
Look a likes: May be confused with bladderworts, hornworts, mermaid weeds, water crowfoots, and leafy water-milfoils.