Hydrilla verticillata (potential Great Lakes invasive species)

  • Hydrilla is a submerged aquatic plant that has invaded waterways in at least 19 U.S. states. If hydrilla spreads to Michigan, it could quickly overwhelm waterways, causing severe ecological and economic impacts.
  • Hydrilla can grow up to an inch per day. It forms large, dense mats near the surface of the water that block recreational access, impede drainage and restrict water movement, causing sediment to accumulate.
  • Thick mats of hydrilla block sunlight and can suffocate native plants and animals that live in the waters below.

Hydrilla Threatens to Invade Michigan Waterways

The invasive Hydrilla plant has not yet been found in Michigan, but scientists aren’t taking any chances. Michigan Sea Grant and partners are asking boaters, anglers, swimmers and waterfront property owners to look for hydrilla (hydrilla verticillata) at favorite lakes, ponds and streams. The aquatic plant has clogged waterways in many southern states and has been found in at least two Great Lakes states, Pennsylvania and most recently in Indiana (see story in news and events). Early detection may spare Michigan a similar fate.

“If hydrilla is found in Michigan, our best chance to stop it from spreading is to act quickly,” says Swinehart, who is a member of Michigan’s Hydrilla Task Force. The task force has recommended strategies to keep the invasive plant out of the state and to respond rapidly if it’s found. One strategy calls for quick action on the part of people who think they’ve spotted hydrilla. Hydrilla Hunt cards (below) provide instructions on how to collect a plant sample using a sharp knife or scissors and where to send the sample for identification. The cards also request contact information and basic information about the location. “We need to know if hydrilla is already here,” says Swinehart. “Michigan citizens play a very important role in helping to monitor the state’s waterways.” If it takes hold, Hydrilla can quickly form thick mats near the water’s surface, suffocate native plants below, degrade water quality and impede recreation, creating severe economic impacts.


Stop Aquatic Hitchhikers! Boat Stickers

Available through Michigan Lake and Stream Association and the MSU County Extension Offices. Produced by the Aquatic Nuisance Species Task Force.

Michigan residents can help by following good invasive species prevention practices when moving watercraft or other water recreation gear from one body of water to another. More information can be found at: www.protectyourwaters.net