Illustration provided by: IFAS, Center for Aquatic Plants, University of Florida, Gainesville, 1990
Some of our aquatic buttercups (for instance the water crowfoot) have similar leaves and could be mistaken for Cabomba except that their leaves are arranged alternately along the stem. On rare occasions fanwort produces small round or triangular shaped floating leaves. Flowers are held above the water surface because, like many other aquatic plants, it relies on conventional airborne pollination (probably flying insects in this case).
Aerial pollination is one line of evidence which supports the idea that aquatic plants evolved from terrestrial ancestors. Fanwort is one of several invasive non-native aquatic plants which have been spreading through New England in recent years and causing much alarm among people with an interest in freshwater resources. Concern stems from the fact that, once established, Cabomba spreads aggressively replacing populations of native species. Unlike most other listed species which have been transported to North America from distant continents, Cabomba is native to the United States. Originally, Cabomba was only found in the Southeast and, perhaps, the Midwest but its popularity as an aquarium plant has provided an effective means of long-distance dispersal. The first report in New England was from Hatfield Massachusetts in 1930 followed by a report from Cranston Rhode Island in 1936. Since then it has spread throughout Connecticut, Massachusetts, and into southeastern New Hampshire. It prefers quiet waters and so, along the River, it is most likely to be found in backwaters, impoundments and oxbow ponds. In Massachusetts, Cabomba is most widespread in the eastern counties, but it has also been reported from all five of the Connecticut River Valley counties and is common in the Millers River Watershed. It has not been reported in the Valley north of the Massachusetts state line, but is abundant in Bartons Cove just a few miles south of the border. A small fragment of stem can root and regenerate a whole plant which can reproduce clonally to cover a vast area in a remarkably short period of time. It is thought that the continued spread of Cabomba in New England is mostly by fragments which can be transported over long distances on floodwaters, migrating wildlife, and boats. After visiting an infested area, it is wise to inspect boats and equipment so as not to inadvertently cause further spread.
