Canadian Pondweed

What is Canadian pondweed?

(Eloda canadensis)
Canadian pondweed, photo: Kiowa Fenner
Generic Weed Distribution Map
  • Canadian pondweed is a weed of freshwater ponds, lakes, reservoirs and rivers in Tasmani
  • Canadian pondweed is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of Canadian pondweed are prohibited in Tasmania.

How to identify Canadian pondweed

  • Canadian pondweed is a perennial (long-lived) freshwater herb, with much branched stems to 3 m long. The leaves are dark green and occur in whorls of three on the middle and terminal parts of the stem, becoming more crowded at the ends of the stem.
  • Canadian pondweed is usually firmly rooted in the bottom mud and forms a thick green mass below the water surface. The flowers are white and unisexual, and are carried towards the water surface by a thread-like extension up to 30 cm long. Plants are either male or female; only male plants occur in Australia. Flowering is in summer.
  • Stem growth begins in September and October as water temperature rises above 15 degrees C, and a thick mat of intertwining stems forms below the water surface. Growth declines in autumn and the plant over-winters in a semi-dormant state. New plants form in autumn as a result of stem fragmentation.
  • For further help in identifying Canadian pondweed, search the Dennis Morris Weeds and Endemic Flora database for Canadian pondweed illustrations. If you are still in doubt about the weed you are dealing with, contact your Regional Weed Management Officer on 1300 368 550 for help.
Strand of Canadian pondweed, photo: Kiowa Fenner
Image top right: Canadian pondweed, photo: Kiowa Fenner
Image above: Strand of Canadian pondweed, photo: Kiowa Fenner

Canadian pondweed in Tasmania

  • Canadian pondweed occurs at several sites in southern, central and northern Tasmania (see map).
  • Canadian pondweed is a serious weed in a variety of freshwater environments, reducing water flow and interfering with recreational activities, hydro-electric operations and irrigation.

What is the legal status of Canadian pondweed in your area?

Detailed management and control guidelines for Canadian pondweed can be found in the Canadian Pondweed Control Guide. Refer also to Herbicides for Aquatic Weed Control. For further information see DPIPWE's Weed Links and Resources.

See also

Canadian Pondweed Control Guide
Herbicides for Aquatic Weed Control
Statutory Management Plan for Canadian Pondweed
Weed Links and Resources

Other useful links
Pest Genie

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