Underwater plant
Curly-leaf Pondweed
Potamogeton crispus
These illustrations are AI-generated, not photographs, and are not to scale. They show what to look for; they are not a substitute for an expert identification.
How to identify it
Size: Leaves about 2 to 4 inches long.
- Leaves with wavy, crinkled edges, like the edge of a lasagna noodle.
- Tiny teeth along the leaf edges. Look closely or run a fingertip along one.
- Olive-green to reddish-brown color.
- Leaves spaced one at a time along the stem, alternating sides.
- In late spring it forms hard, bur-like buds called turions that sink and sprout later.
Don’t confuse it with
Native clasping-leaf pondweed has wavy leaf edges too, so waviness does not tell them apart. Its edges have no teeth — run a fingertip along one — and its leaf bases wrap right around the stem.
Where it came from
Native to Europe, Asia, Africa and Australia.
Present in North America since at least the mid-1800s. It spreads by stem pieces and turions carried on boats and gear.
Earliest dated Indiana record: 1913, Wolf Lake, Lake County. This is the oldest dated record in the USGS non-native species database, not necessarily when it first arrived.
Why it matters
It starts growing very early, even under ice, and can form thick mats in spring before native plants get going. It dies back in early summer, and the rotting plants can release nutrients that feed algae blooms.
Indiana law
Listed in Indiana's Aquatic Plant Rule (312 IAC 18-3-23), which makes it illegal to sell, give away, barter, exchange, distribute, transport or introduce the plant in Indiana. Fines can apply for carrying listed plants on vehicles, boats or trailers. Indiana DNR’s page.
If you find it
- Don’t move it. Before leaving the water, remove all plants, mud and debris and drain all water from your boat, motor, live well, bilge and trailer. Carrying plants listed in Indiana’s Aquatic Plant Rule on vehicles, boats or trailers is illegal and can bring fines. Clean boater tips
- Never release bait or pets. Don’t dump bait, aquarium animals or water-garden plants into any lake or stream. Put unused bait in the trash.
- Report it. Take a photo, note where you saw it, and report it through EDDMapS or the GLEDN phone app, or contact Indiana DNR’s aquatic invasive species program at 317-234-3883 or ais@dnr.IN.gov. Experts there can confirm what you found.
- Ask before removing or treating. On public lakes, any control of aquatic plants — chemical, mechanical, physical or biological — needs an Indiana DNR aquatic vegetation control permit. When a permit is needed
Indiana lakes where it has been recorded
6 Indiana lakes on this site have a record of this species.
Jackson
LaGrange
Steuben
Tippecanoe
Washington
A lake that is not listed may still have it. Records exist only where someone found the species and reported it, so “not recorded” does not mean “not present.”
Lake records: Midwest Glacial Lakes Partnership Conservation Planner; underlying records from the USGS Nonindigenous Aquatic Species database.
Sources
- Midwest Invasive Species Information Network: Curly-leaf pondweed
- Indiana DNR: Aquatic invasive species, plants
- Indiana Aquatic Plant Rule, 312 IAC 18-3-23: what you need to know
Earliest dated record: USGS Nonindigenous Aquatic Species database.