Curly-Leaf Pondweed (CLP)
Where does CLP grow naturally, and how did it get here?
CLP is native to Europe and Asia. It spread to North America through boats and the aquarium trade. It moves from lake to lake in Wisconsin via boaters, especially through its overwintering buds, called turions.
An interesting life history
CLP is usually the first plant in lakes to appear in the spring. This is because it starts growing during the winter under the ice! CLP matures by early summer, and begins to produce turions, which are the overwintering buds CLP uses to reproduce.
The turions fall off the plant around July 4th, sinking into the sediment below. These turions sprout into new plants during the winter. Turions may sprout later that same year, or they may sit in the sediment for up to 7 years before sprouting. This makes treating CLP particularly difficult, as we can never be sure of the turion seedbank within the sediment. CLP treatment must be a vigilant, multi-year approach.
How do I identify CLP?
The leaves of CLP are finely serrated, giving it a jagged, tooth-like appearance. This also causes the plant to feel more coarse. When you hold a single leaf of CLP, it looks similar to a lasagna noodle (hence “curly leaf” pondweed).
CLP is most often confused with clasping leaf pondweed, which does not have serrated leaf edges, and also has leaves that “clasp” around the stem.
If you suspect you have found CLP in your lake, please contact our Water Program Coordinator for verification.
How does CLP impact a Wisconsin lake?
CLP out-competes native plants in water bodies, and can grow so quickly that it can cause surface matting. This interferes with recreational usage of lakes. The matted CLP also blocks sunlight from native plants. Once the CLP dies off in mid-summer, little vegetation is left where CLP was growing, thereby removing habitat for other critters that live in the lake.
What can be done once CLP enters a water body?
Because CLP has a unique life history, and can potentially build up a large "seed bank" of turions, treatment of CLP is often a multi-year process. Some chemicals, such as endothall, have successfully depleted CLP populations. However, these chemicals require a permit, can be expensive, and are non-selective (meaning they can potentially kill any plant that comes in contact with the chemical).
If CLP populations are smaller, hand-harvesting of CLP has shown promising potential. Your lake group could hire professional divers, or could have volunteers hand-pull CLP. Please contact the Water Program Coordinator if you have any questions about CLP hand removal.
Manitowish Waters Lakes Association
Wisconsin DNR Aquatic Invasive Species
Citizen Lake Monitoring Network: Get Involved!
Great Lakes Indian Fish & Wildlife Commission (GLIFWC) Invasive Species Area Maps
US Geological Survey Invasive Species Research
Vilas County Land and Water Conservation Department
Invasive Plants Association of Wisconsin
Available for loan.
Lake Plants You Should Know- A Visual Field Guide. University of Wisconsin- Extension.
Aquatic Plants of the Upper Midwest- A Photographic Field Guide To Our Underwater Forests.Written by: Paul Skawinski.
Through the Looking Glass- A Field Guide to Aquatic Plants. Written by: Susan Borman, Robert Korth, and Jo Temte.
Saving Our Lakes and Streams. Written by: James A. Brakken.
Your Help Is Needed
Curly leaf pondweed has been found in the Manitowish Waters Chain. Please keep your eyes open and let us know if you see this aquatic invasive plant along your shorelines or docks. Additionally, please check your boats and props to prevent the spread!
Citizen AIS Lake Monitoring
Join a crew to search for suspicious-looking species (plant or animal). Keep your eyes peeled and report any sightings to us.
Clean Boats Clean Waters
Educate boaters at landings and inspect boats and trailers.
Volunteer today, to protect our waters tomorrow.
Phone: (715) 543-2085
AIS of the Month
September: Mystery Snails
August: Eurasian Water Milfoil
July: Purple Loosestrife
June: Curly Leaf Pondweed