hydrilla logoGo on a Hydrilla Hunt!

Keep an eye out for this highly invasive aquatic plant

Hydrilla (Hydrilla verticillata) is a highly invasive aquatic plant that threatens the health of Illinois' lakes and rivers — as well as waterfront property values and our enjoyment of fishing, boating, and swimming. Boaters, anglers, swimmers, and others who enjoy Illinois’ lakes and rivers are keeping their eyes peeled this summer for an aquatic “superweed.”

Recognized as one of the world's worst weeds, hydrilla can grow an inch per day and form dense mats of vegetation at the water surface. Within the past few years, hydrilla has been discovered in Wisconsin and Indiana and it is expected to arrive in Illinois very soon. Our desirable native aquatic plants, sport fishing, native wildlife, waterfront property values, and recreational uses might all be seriously impacted.


The photos above illustrate how dense hydrilla can grow in a very short period of time: just 18 days elapsed between these two photos!

"Early detection of hydrilla could save Illinois millions of dollars in control costs," noted Cathy McGlynn, coordinator for the Northeast Illinois Invasive Plant Partnership (NIIPP). "Experience from other states shows that once a waterway becomes infested with hydrilla, it's nearly impossible to control. Our hope in Illinois is to identify the plant at a very early stage when populations are still small enough to eradicate and manage," added McGlynn.

hydrillahydrilla close up

The photos above are a close-up view of hydrilla courtesy of Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.

The strain of hydrilla that has been found in the northern United States is believed to have originated in Korea. It grows on mucky as well as sandy bottoms of lakes and rivers, and from very shallow water to depths of 20 feet or more. It can be spotted snagged on fishing lines or on boat anchors, or by noting plants seen while boating or growing along the sides of a pier. Hydrilla spreads quickly, since just a small stem fragment of hydrilla can sprout roots and grow into a whole new plant.

Anyone can participate in the Hydrilla Hunt! program. Volunteers are encouraged to take a more detailed look at aquatic plants they encounter while out and about on Illinois’ waterways.

If you think you have found hydrilla, please use your phone or digital camera to take one or two close up photos of a plant stem on a light-colored background (then discard the plant fragment in the trash). Please email your photos to the Hydrilla Hunt! program at HydrillaHunt@niipp.net and include a brief description of where it was found (e.g., county, lake, boat ramp, etc.). They will acknowledge receipt of your email and let you know what they see. If you're not able to send them a digital picture, email them so they can contact you.

For more information, visit this Hydrilla information page. The Hydrilla Hunt! program is coordinated by the Northeast Illinois Invasive Plant Partnership, the Chicago Botanic Garden, and the Lake County Health Department-Lakes Management Unit. Funding support has been provided by the Illinois Department of Natural Resources through the Illinois-Indiana Sea Grant.

See here for more information about water hyacinth.