Appearance

Curly pondweed is made up of broad leaves with curly, finely toothed edges. These leaves grow to 1 to 4 inches long and grow alternately or slightly opposite on flat, branched stems. In winter, leaves are blue-green and more flattened; in spring and summer, leaves are reddish-brown and become wider and curlier. Curly pondweed has a shallow root and rhizome system.

Reproduction and Life Cycle

Curly pondweed has a three-stage life cycle. During spring and summer, flowers bloom and float at the water’s surface. It begins to die in mid-summer after producing buds, which lie dormant until autumn. In winter, the spring/summer cycle repeats itself when buds sprout into new flowers. It can also reproduce asexually when rhizomes or burr-like structures near the tips of the stems develop into new plants.

Did You Know?

• Curly pondweed was likely introduced to the United States in the mid-1800s.
• It can become invasive in non-tidal waters because it grows early in the season and can shade out other bay grasses.
• Curly pondweed can be confused with young shoots of redhead grass.

Sources and Additional Information

• Underwater Grasses in Chesapeake Bay & Mid-Atlantic Coastal Waters by Maryland Sea Grant
• Bay Grass Key: Curly Pondweed – Maryland Department of Natural Resources
• Weed Identification Guide: Curly Pondweed – Virginia Tech
• Invasive Plants in Pennsylvania: Curly Pondweed – Pennsylvania Department of Conservation and Natural Resources
• PLANTS Database: Potamogeton crispus – USDA Natural Resources Conservation Service