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Curly-leaf pondweed

(Potamogeton crispus)

Photo of curly-leaf pondweed
Photo credit: Wisconsin DNR

A perennial, submerged aquatic herb that is native to Eurasia. Tolerates fresh or slightly brackish water and can grow in shallow, deep, still or flowing water.

Overview

Other names for this plant include:
  • Common names: curled pondweed, crisped pondweed
Ecological threat:
  • It invades freshwater lakes, ponds, rivers, streams, and in slightly brackish waters. It can become dominant and invasive due to its tolerance for low light and low water temperatures.
  • May outcompete other underwater plants and become dominant, which causes problems due to the formation of dense mats that interfere with recreational activities.
  • It also causes an increase in phosphorus concentrations, causing an increase in algae blooms and a pile-up of dying P. crispus along the shore.
Overview map of curly-leaf pondweed classification in WI
Restricted (orange) counties

Classification in Wisconsin: Restricted

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for curly-leaf pondweed was based upon this literature review [PDF] developed by the department.

Identification

Leaves: All submersed and alternate with no leaf stalks; oblong, still, translucent leaves (4-10 cm long, 5-10 mm wide) have distinctly wavy edges with fine teeth and 3 main veins. Sheaths (stipules) up to 1 cm long are free of the leaf base and disintegrate with age.

Flowers: Tiny, with 4 petal-like lobes; in spikes 1-3 cm long on stalks up to 7 cm long.

Fruits & seeds: Seed-like achene (4-6mm long including 2-3 mm beak, back ridged).

Roots: Fibrous, from slender rhizomes.

Similar species: There are many native Potamogeton species native to Wisconsin.

Distribution

See the reported locations of curly-leaf pondweed in Wisconsin.

Do you know of additional populations? Send us a report.

Control

Mechanical: Due to the early growth period, management should happen in spring or early summer. Raking, cutting or harvesting reduces biomass and possibly reduces the production of turions.

Chemical: Diquat, endothall and fluridone can be effective.

Photos

View curly-leaf pondweed pictures in our photo gallery!

Resources

Sources for content: Links for more information: