Fanwort
Cabomba caroliniana
Washington State Classification
Class B — Control Required (Designated)
It is an extremely persistent and competitive plant that grows densely and crowds out native species.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Fanwort is a submersed, floating (often rooted) perennial, with short, fragile rhizomes. Erect shoots are upturned extensions of horizontal rhizomes.
Leaves
They are light to olive green and sometimes reddish brown. Two leaf types present—submersed and floating. Submersed leaves are oppositely arranged, fan-shaped and finely divided. Floating leaves are alternately arranged, narrow and appear near stem tips.
Flowers
Flowers are small, less than 1/2 inch in diameter and float on the water. Flowers have 3 petals and 3 sepals. White petals have yellow coloring at the base.
Fruit & Seeds
Flowers form 2 to 4 leathery pods with each having 1 to 3 seeds.
Impact
It is an extremely persistent and competitive plant that grows densely and crowds out native species. It can clog drainage canals and freshwater streams. It can also prevent recreational activities and normal water flow requiring costly control measures.
Ecology & Spread
Habitat
The species grows rooted in the mud of stagnant or slow flowing water including streams, smaller rivers, lakes, ponds, sloughs, and ditches. Please click here to see a county level distribution map of fanwort in Washington.
Spread Mechanisms
Reproduction
Fanwort reproduces by seed, rhizomes and stem fragments.
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Control Methods
Biological Control
- Grass carp will eat fanwort, but it is not a preferred food.