Nymphoides cristata

Common Name(s): Crested floating heart

Non-Native to Florida

The numerous small heart-shaped leaves of Nymphoides cristata float on the water surface while roots grow into the hydrosoil. Five-petaled white flowers rise on small stalks above the leaves. A white ruffle lining the middle of each petal distinguishes the plant from the two native species in the same genus.

Nymphoides species have escaped from the ornamental plant trade over the past decade and become established in South Florida canals. The native Nymphoides species (N. aquatica and N. cordata) are usually found in shallow wetlands and littoral areas of lakes and not considered a problem.

The exotic N. cristata and Nymphoides indica are widely sold in the nursery and water garden trade and come from Asia. Of these, N. cristata is rapidly spreading. It occurs in south Florida canals, stormwater treatment areas, several central Florida canals, and north into South Carolina in the Santee-Cooper reservoir. It has become a serious weed problem in south Florida canals. The introduced species may look just as lovely, but it quickly covers the water surface with a canopy of leaves and shades out the plants below.

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).Out of state, it is found growing abundantly in Lake Marion, South Carolina.

 

 

For Best Management Practice (BMP) control trials, see the following excerpts from Best Management Practices (BMP’s) for Nymphoides Control by Atul Puri and W.T. Haller (June 2010) UF/IFAS Center for Aquatic and Invasive Plants, Annual Report – FWC Task 155. (Editor’s note: Information on Rotala rotundifolia was excised to make the report specific to Nymphoides. See Rotala rotundifolia for BMP information on that species from Annual Report – FWC Task 155.)

 

Abstract

Studies were conducted in mesocosms as well as in South Florida canals to develop best herbicidal management programs for Nymphoides indica. Treatments included imazamox (50, 100, 200, 400 ppb), endothall (0.25, 0.5, 1.5 and 2.5 ppm), triclopyr (0.5, 1, 2, 2.5 ppm), flumioxazin (50, 100, 200, 400 ppb) and UF-20 (25, 50, 100, 200 ppb). For N. cristata, endothall was 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 was also effective at higher doses of 200 and 400 ppb and gave 82 and 87% control of Nymphoides, respectively. Tryclopyr and imazamox were the least effective treatments and even maximum labeled rate of tryclopyr (2.5 ppm) gave only 55% control. Results of field trials were similar. Submersed treatments of endothall at 2-3 ppm gave about 80-90% control 8 WAT. Other herbicide treatments were not effective in controlling this weed species. 2,4-D @ 1 ppm gave 93% and at 2 ppm provided 99% control and diquat @ 400 ppb provided 80% control. 2, 4 D was also effective at higher doses of 200 and 400 ppb and gave 82 and 87% control of Nymphoides, respectively. Other herbicide treatments were not effective in controlling this weed species.

Introduction

In the past decade, Nymphoides has escaped the ornamental plant trade and become established in South Florida canals. The native Nymphoides species are usually found in shallow wetlands and littoral areas of lakes and never considered a problem.

The snowflake or crested floating-heart (N. cristata), which arrived from Asia in the past 6 years, is also spreading through Florida. N. cristata has become a serious weed problem in the south Florida canals. Its heart-shaped leaves float on the water surface and five-petaled white flowers rise on little stalks above the leaves. A white ruffle lining the middle of each petal distinguishes the plant from the two natives in the same genus. The introduced species may look just as lovely, but it quickly covers the water surface with a canopy of its leaves and shades out the native plants underneath. The exotic N. indica and cristata are widely sold in the nursery and water garden trade. Of these, N. cristata is very aggressive and is rapidly spreading in southern Florida. It occurs in South Florida canals, storm water treatment areas, several central Florida canals and north into South Carolina, in the Santee-Cooper reservoir.

N. cristata roots into the hydrosoil and produces numerous small floating leaves on the water surface. Most of the plant biomass is below the water surface, so foliar applications have had only limited success.

Methodology

Studies have been conducted at the University of Florida-IFAS, Center for Aquatic and Invasive Plants (CAIP), in Gainesville, FL. N. cristata plants were planted in 30 cm diameter plastic pots filled with 2/3 potting media covered with 1-2 inches of sand. After one month, these plants were transferred to 900 L concrete vaults (two pots per vault) each vault serving as a replication. Treatments included imazamox (50, 100, 200, 400 ppb), endothall (0.25, 0.5, 1.5 and 2.5 ppm), triclopyr (0.5, 1, 2, 2.5 ppm), flumioxazin (50, 100, 200, 400 ppb) and UF-20 (25, 50, 100, 200 ppb). Visual injury ratings were taken 2 weeks after treatment (WAT) and 6 WAT. Plants were harvested 8 WAT and above ground biomass was determined as dry wt/plant. Plants were dried for 1 week, weighed, and statistically analyzed for treatment differences.

Results and Discussion

The effect of herbicides in the mesocosm study was evaluated by visual estimates (% control) and dry weight analysis on N. cristata (Tables 1 and 2). Endothall was 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 was also effective at doses of 200 and 400 ppb and gave 82 and 87% control of Nymphoides, respectively. Tryclopyr and imazamox were the least effective treatments and even the maximum labeled dose of tryclopyr (2.5 ppm) gave only 55% control. Submersed treatments of endothall at 2 to 3 ppm gave about 80-90% control 8 WAT. Other herbicide treatments were not effective in controlling the Nymphoides species.

Table 1: Visual Injury symptoms at 2 and 6 WAT of Nymphoides cristata after application of herbicides; 0 %- No control, 100%: total death.

Herbicides

Rate

2WAT

6WAT
Imazamox 50ppb 12.5±2.5* 42.5±2.5
100ppb 15±5 52.5±2.5
200ppb 15±5 67.5±2.5
400ppb 17.5±7.5 77.5±2
Endothall 0.25ppm 52.5±2.5 77.5±2.5
0.5ppm 72.5±2.5 92.5±2
1.5ppm 92.5±2.5 98.5±1.5
2.5ppm 98.5±0.5 100±0
Flumioxazin 50ppb 25±0.5 52.5±2.5
100ppb 52.5±2.5 62.5±2
200ppb 72.5±2.5 82.5±1.5
400ppb 80±0.5 87.5±2.5
Triclopyr 0.5ppm 0 22.5±2
1ppm 12±2.5 35±5
2ppm 20±0.5 42.5±7.5
2.5ppm 32.5±2.5 55±5

* Mean values presented with standard error

Table 2: Effect of herbicides on dry weight of N. cristata 8 WAT in concrete tanks

Herbicides

Rate (mg/L)

Dry wt 8-WAT1
Untreated   50 ± 4
Triclopyr 2.502 28 ± 4
Imazamox 0.402 12 ± 1
Flumioxazin 0.402 12 ± 3
Topramazone 0.202 2 ± 0.3
Endothall 0.25 27 ± 1
Endothall 0.50 9 ± 1
Endothall 1.50 0
Endothall 2.50 0

1 Mean values with standard error

2 Maximum rate of each herbicide tested

Future Studies

Field trials in South Florida canals infested with Nymphoides treatments are planned. We will evaluate the herbicides which looked most promising in the greenhouse studies.

 

 

More Resources

View the herbarium specimen image from the University of Florida Herbarium Digital Imaging Projects.

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Citations

1. Invasive and Non-native Plants You Should Know – Recognition Cards,
by A. Richard and V. Ramey. University of Florida-IFAS Publication # SP 431. 2007.

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