What to look for:
- Free-floating aquatic plant sometimes rooted in shallow water.
- Leaves are small, 0.5-2.5 inches, round to heart-shaped, with a purple-red underside.
- Leaves form a rosette.
- Single flower with three white petals and yellow center may be visible from June to August.
European frog-bit plants resemble miniature water lilies.
Plants can form dense mats, often among cattails or other shallow-water vegetation.
European frog-bit turions are seed-like buds or small shoots that detach and can form new plants.
About this species:
Habitat: European frog-bit is most often found in slow moving rivers, sheltered inlets, ponds, bayous and ditches. Prefers waters rich in calcium with no wave action.
Native Range: Europe, Asia and Africa.
U.S. Distribution: New York, Michigan, Ohio, Pennsylvania, Vermont, Washington. Also found in Quebec and Ontario, Canada.
Michigan Distribution: European frog-bit is widespread along the coastal areas of lakes Erie and Huron up to the eastern Upper Peninsula and has been found in inland lakes and ponds in southeast Michigan. In west Michigan, the plant has been found in inland lakes in Kent County as well as the Lower Grand River in Ottawa County and Pentwater Lake in Oceana County.
- Map of European frog-bit observations in the Lower Grand River 2019 - printable PDF
- Map of European frob-bit observations in Pentwater Lake 2019 - printable PDF
Local Concern: European frog-bit can form dense mats on the surface of slow-moving waters like bayous, backwaters and wetlands. Mats of European frog-bit can impede boat traffic and alter food and habitat for ducks and fish. Prolific growth of aquatic invasive plants like European frog-bit can also reduce oxygen and light in the water column.
Means of Introduction or Spread: European frog-bit is often introduced to new water bodies when plants or turions are transported on boats, trailers and recreational gear. Once established, drifting mats of vegetation can spread to connected waters.
High Risk Pathways: boating, hunting.
Treatment: Manual removal in the spring or early summer can be effective for small populations but requires repeated efforts to maintain control. Certain chemical treatments have also been used to reduce European frog-bit. Information on chemical treatments can be found in Michigan’s Status and Strategy for European Frog-bit Management.
European Frog-bit Poster for Waterfowl Hunters - Printable PDF
European Frog-bit Identification and Reporting - Downloadable PowerPoint presentation
Status and Strategy for European Frog-bit Management - Printable PDF. This document provides in-depth information about European frog-bit in Michigan including identification, distribution, management and control options.
MDARD Weed Risk Assessment for European Frog-bit (Hydrocharis morsus-ranae) - Printable PDF. This document evaluates the invasive potential of the plant species using information based on establishment, spread and potential to cause harm.