Frogbit, a prohibited invasive aquatic plant, has been spotted in two locations near Lake Michigan as state officials and researchers are warning boaters of a new law to prevent further spreading.

The European frogbit is living in Michigan's lower Grand River upstream of Grand Haven in Ottawa County and in Pentwater Lake in Oceana County, officials with the Department of Environment, Great Lakes and Energy said. 

The plant, which resembles a miniature water lily with heart-shaped leaves about the size of a quarter, quickly forms dense colonies or mats that prevent native plant growth. The plant can make movement difficult for ducks and large fish, and cause problems for boaters, anglers and swimmers, the DNR said.

Officials are warning Michigan residents that plant parts "easily can be transported to new water bodies on boat motors or trailers, fishing gear and other recreational equipment" and should review a new state law that requires boaters to heed the plant.

The law, effective in March, says after trailering boats, and before getting on the road, boaters must pull plugs, drain water and remove plants and debris. 

"Duck hunters who use these areas should check boats, blinds and even dogs for plants or turions (small buds that break off the plant) that can spread European frogbit," said Kevin Walters, a biologist with state department's aquatic invasive species program, who hopes the simple steps will prevent it from spreading to new locations.

The species was first detected in southeast Michigan in 1996 and has since spread along coastal areas of lakes Erie and Huron up to the eastern Upper Peninsula.

In 2016, the plant was discovered in Reeds and Fisk lakes in East Grand Rapids, the westernmost known point of detection in the United States until now, officials said.

Walters came across a floating mat of European frogbit while boating in the Grand River with his family in late July.

"While my professional work focuses on invasive species, this sighting while enjoying time on the water with my kids is a reminder about the important role boaters, anglers and waterfowl hunters play in preventing the spread of invasive species," Walters said.

European frogbit does not anchor its roots in the lake or stream bed but remains free-floating and can build up. Three-petaled white flowers with yellow centers appear briefly sometime between mid-July and mid-August, the DNR said.

It spreads by plant fragments or by turions and spends the winter in lake or stream beds; and thrives in slow-moving waters with little to no wave action, researchers say.

To better understand where it is spreading in Michigan and what should be done in response, the Department of Environment, Great Lakes and Energy is collaborating with the West Michigan CISMA and the Match-E-Be-Nash-She-Wish Band of Pottawatomi Indians (Gun Lake Tribe) on surveys.

An initial survey of the lower Grand River started in late August and so far, crews have found multiple patches of the invasive plant.

"We are using both small boats and kayaks in order to survey the river and its backwaters," said Drew Rayner, West Michigan CISMA coordinator. "Our plan is to complete surveys on both water bodies this fall to determine the extent of the infestation. If weather permits, we will also begin surveying nearby waterways."

The plant has been detected s far as 144th Avenue, approximately 5 miles upstream of the original detection, the DNR said.

Officials are also asking residents to help by reporting suspected European frogbit to the Midwest Invasive Species Information Network website, at or by downloading the MISIN app to a smartphone. Be sure to take photos and track your location.

Twitter: @SarahRahal_

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