Invasive Frog-bit

Environmental Effects | Treatment | Resources

Invasive frog-bit (Hydrocharis morsus-ranae) is a prohibited species in the state of Michigan. This means that selling, importing, cultivating or transporting this species is not allowed. It is becoming increasingly distributed in the state especially in in-land waters, and on-going survey work seeks to determine where it is present.

This species looks like a mini lily pad with the pad reaching 1-2 centimeters across. It is free-floating and can be pulled from the water to inspect. The plants have white three-petaled flowers with yellow centers.

Currently, it has been identified in Novi and Northville. Please immediately report this species to the CISMA if observed! Please include photos to help with identification. OC CISMA has been working on survey and treatment of European frog-bit since its detection in Oakland County in 2018. Read more about the EFB survey and treatment projects here.

Michigan.gov species profile
more pictures

Environmental effects

Invasive frog-bit grows rapidly, forming thick mats. Since this species floats, it easily spreads via the movement of water, boats, or waterfowl. Frog-bit also produces turions, wintering buds that fall to the bottom of the water body and sprout plants in future years.

The thick mats that this species can form impede boat travel, prevent ducks from landing and block light from reaching plants below the surface. Additionally, the die off of thick mats can lead to low oxygen conditions in the water, affecting fish, turtles and frogs.

Treatment

Research is ongoing throughout the state to determine the best treatment methods for Invasive Frog-bit. Please ask your local CISMA for advice on treatment. Below are some treatments that have resulted in reduced frog-bit populations.

Small populations of frog-bit can be easily pulled out of the water by hand, as it is a free-floating plant. Removed plants should be thrown away in black garbage bags or placed somewhere where they can dry out.

Resources

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