Curly Leaf Pondweed – Oneida County Aquatic Invasive Species Program

Identification: Dark green with reddish hued leaves. Wavy margins on the sides of the leaves resembling lasagna noodles. Leaf margins have small teeth. Plants may grow up to two meters long.

Ecology and Natural History: Curly-leaf pondweed’s native range includes Eurasia, Africa, and Australia. The species was introduced intentionally for waterfowl and wildlife habitat. It has spread as a contaminant in water used by fish hatcheries and by plant fragments attached to boats and equipment that are not properly cleaned. Curly-leaf pondweed prefers quiet waters. It is found in brackish, alkaline, or eutrophic waters. It is usually in less than three meters of water but can be found in up to twelve meters of water. Curly-leaf pondweed flowers in late spring/early summer. It produces turions which germinate in late summer/fall.

Impact of Introduction: Curly-leaf pondweed grows in dense colonies that compete and displace native plants. The dense colonies can form mats on the surface of the water that impede transportation and recreation. The dense mats increase phosphorus concentrations which will cause an increase in algae blooms. After the plant decomposes, the concentration of oxygen in the water can drop significantly and impact fish.

Oneida County Waterbodies with Curly-Leaf Pondweed: Hancock Lake, Horsehead Lake, Johnson Lake, Kawaguesaga Lake, Lake Nokomis, Manson Lake, Mid Lake, Minocqua Lake, Pelican Lake, Rainbow Flowage, Rhinelander Flowage, Tomahawk Lake, Tomahawk River, and Upper Post Lake.