Watch Out for European Frog-Bit

By: Emma Costantino
North Country Cooperative Invasive Species Management Area

Many unwanted aquatic plants have been moving into Michigan’s waters. One example of a plant you do not want to see floating in your lake is European frog-bit.

One of several invasive plants on the Michigan watch list, European frog-bit is a free-floating aquatic plant. Its dangling roots tend to tangle, creating dense floating mats. These mats of frog-bit can cover the water’s surface and create a host of problems. They crowd out native plant species and reduce the biodiversity in a lake. It is also difficult to recreate in waters covered in European frog-bit. The plants get in the way of swimmers and tangle in paddles and boat motors.

European frog-bit can sometimes be mistaken for waterlilies because they have similar looking leaves. Both plants have heart-shaped leaves, but European frog-bits are much smaller, between 0.5-2.25 inches wide. The undersides of European frog-bit leaves are also a purplish-red color. The plant produces three-petaled white flowers with yellow centers.

People often spread European frog-bit by accident. Seeds and plant fragments are carried from lake to lake by boats and aquatic gear. According to Erick Elgin, a Water Resource Educator at Michigan State University Extension, “The invasion of European frog-bit is in a critical stage since it is not widespread across Michigan. Currently state agencies and conservation partners are responding to sightings to contain, control, and eradicate it if possible. However, if European frog-bit continues to spread into new waterbodies, eradication efforts may become ineffective. Therefore, it is extremely important to clean, drain, and dry boats and gear thoroughly after each outing and to report sightings.”

Besides cleaning boats and equipment to stop European frog-bit, there are other steps people can take to prevent this invasive plant from spreading in the state. Early identification is key, and by enrolling in the Exotic Aquatic Plant Watch (EAPW) is a great way to gain the skills needed to spot this species. The EAPW trains participants trains participants to monitor lakes for five aquatic invasive plants, including European frog-bit. For more information, attend the upcoming Exotic Aquatic Plant Watch Q&A Session. The event will take place online on April 15 at 3pm. Sign up for free at

Emma Costantino is the North Country Cooperative Invasive Species Management Area (NCCISMA) Outreach Coordinator. She can be reached by calling (313) 570-6853 or by emailing