Curly-leaf Pondweed (Potamogeton crispus)
Curly-leaf pondweed (Potamogeton crispus) is a rooted submerged plant that quickly forms dense mats at the water surface of lakes and rivers in late spring and early summer. In late fall and early winter, it sprouts from rhizomes and turions (overwintering buds) shading out later growing native plants. Mats interfere with boating, fishing, waterfowl hunting, and swimming. Summer die-offs can form windrows of decaying plants on shore, sometimes followed by algal blooms. Curly-leaf pondweed displaces native plant communities and decay can deplete oxygen levels, leading to fish kills and impacts on other aquatic life.
Native to Eurasia, Africa and Australia, curly-leaf pondweed was first discovered in North America in the mid 1880s. By 1978, it had spread across most of the United States and Canada. It spreads by seeds, rhizomes, turions, and plant pieces that break off and float on water currents. It can spread overland to new waters by clinging to watercraft, trailers, and equipment. Eradicating established curly-leaf pondweed infestations is nearly impossible. Your actions and your help in reporting new infestations are vital for preventing their spread.
Identify Curly-leaf Pondweed
- Tolerant of low light, it grows throughout the winter
- Forms floating mats in littoral areas in lakes, ponds, and moderately flowing rivers
- May be confused with largeleaf pondweed or claspingleaf pondweed
What You Can Do
- Learn to recognize curly-leaf pondweed.
Follow Minnesota Aquatic Invasive Species Laws:
- Clean all aquatic plants, animals and mud from watercraft, trailers, docks, lifts, anchors and other recreational equipment before leaving access.
- Drain water-related equipment (boat, ballast tanks, portable bait containers, motor) and drain bilge, livewell and baitwell by removing drain plugs before leaving water access. Keep drain plugs out while transporting watercraft.
- Dispose of unwanted bait, worms and fish parts in the trash.
- Spray watercraft and equipment with high-pressure water, or
- Rinse with very hot water, or
- Dry for at least 5 days.
Report New Sightings — note exact location; wrap a plant fragment in a wet paper towel, place in a sealed plastic bag; and call a Minnesota DNR Invasive Species Specialist (see www.mndnr.gov/invasives/contacts.html), 1-888-MINNDNR or (651) 259-5100; or the Minnesota Sea Grant Program in Duluth, (218) 726-8712.
Know the Rules!
Specimens are needed to confirm sightings, but some jurisdictions prohibit possession and transport of invasive aquatic plants and animals. Contact your local natural resource management agency for instructions. Unauthorized introduction of plants, fish, or invertebrates into the wild is illegal. Protect your property and our waters.