Invasive Species Sheet - Fanwort

Invasive Species Identification Sheet

Fanwort (Cabomba caroliniana A. Gray)

- herbaceous water plant
- underwater leaves with repeatedly forking, thread-like divisions
- underwater leaves are opposite, and have clearly seen stalks

The majority of Fanwort leaves are of the form found under the water. These highly dissected leaves are somewhat stiff, roundish in outline, 3/4"-2" wide, and resemble a flat to slightly cupped, round fan with the 1/2"-1 1/4" long leaf stalk being the fan handle.

Sometimes Fanwort also has a few floating leaves that are oval-shaped or forked on one end, but not toothed. These leaves may be alternate and are about 1/4 "-3/4" long with the leafstalk attached in the middle of the leaf’s underside (peltate leaves). Flowers growing singly from stalks 1"-4" in length may be found floating among these leaves in July-August. The flowers, up to 3/4" across, are white to lavender with yellow centers. Fanwort reproduces mainly from stem fragments.

Fanwort is native from Virginia to southern Illinois and eastern Missouri, south to Florida and Texas. By 1950, it was considered naturalized north to Massachusetts, New York, and Ohio (Gray’s Manual of Botany). Fanwort has been (and continues to be) sold in aquarium stores. It is spread beyond its native range primarily by people and boats. Fanwort can grow aggressively and clog drainage canals, ponds, lakes, reservoirs, and slow-moving freshwater streams.