Curly-leaf pondweed

Curly-leaf pondweed (Potamogeton crispus)

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

Regulated areas of curly-leaf pondweed
Curl-leaf pondweed is Restricted (Orange counties)

Other names for this plant include:

  • Common names: curled pondweed, crisped pondweed

Ecological threat:

  • Invades freshwater lakes, ponds, rivers, streams, and in slightly brackish waters. 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.
  • Also causes an increase in phosphorus concentrations, causing an increase in algae blooms and a pile up of dying P. crispus along the shore.

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 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.

Do you know of addition curly-leaf pondweed 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 reduce biomass and possibly reduce the production of turions.

Chemical: Diquat, endothall, and floridone can be effective.

Photos

View curly-leaf pondweed pictures in our photo gallery!

Resources

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Last revised: Wednesday December 19 2012