The introduced species may look lovely, but it quickly covers the water surface with a canopy of leaves and shades out the plants below. (Richard & Ramey 2007)
An herbaceous aquatic plant with floating stems from a buried rootstock. Slender tuberous roots dangle from the stem-leaf node. A single, heart-shaped Leaf with smooth margins, cordate base, and short petiole at the tip of each stem. Flowers white, with membranous margins, 0.3-0.9” wide, petal lobes with a ruffled crest (like a rooster’s comb) along the upper midvein, blooming from summer to fall. Fruit an oblong capsule with smooth, rounded seeds.
A white ruffle lining the middle of each petal distinguishes the plant from the two native species in the same genus (Richard & Ramey 2007).
The exotic N. cristata are widely sold in the nursery and water garden trade and come from Asia. Nymphoides species have escaped from the ornamental plant trade over the past decade and become established in South Florida canals. The native Nymphoides species are usually found in shallow wetlands and littoral areas of lakes and not considered a problem (Richard & Ramey 2007).
Plants have been confirmed in Broward, Collier (in Big Cypress National Preserve), Hillsborough, Lee, Orange, Palm Beach, Sarasota, Osceola, and St. Johns Counties (Wunderlin 2011). In 2010, it was found growing in scattered locations in Lake Okeechobee (Renney, personal communication 2011).
Endothall is the most effective herbicide and gave 98-100% control at 1.5 and 2.5 ppm. UF-20 at 100 and 200 ppb gave 82 and 93% control, respectively. Flumioxazin is also effective at doses of 200 and 400 ppb and gave 82% and 87% control of Nymphoides, respectively (Puri & Haller 2010).