What is egeria?

(Egeria densa)
EgeriaGeneric Weed Distribution Map
Image: Egeria stem, photo: Stephen Welsh

  • Egeria is a weed of freshwater ponds, lakes, reservoirs and slow moving streams.
  • Egeria is a declared weed in Tasmania under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of egeria are prohibited in Tasmania.

How to identify egeria

  • Egeria is a submerged, perennial (long-lived) freshwater herb, the stems of which may grow to 5 m long. Egeria is usually firmly rooted in the bottom mud, but may occur as a free floating mat near the water surface.
  • The stems are green to brown in colour, much branched, and bear whorls of strap-like leaves which become densely clustered together on the middle and upper stem. The flowers are large, white and unisexual. Plants are either male or female; only male plants occur in Australia.
  • Stem growth begins as water temperature rises above 15 degrees C, and a thick mat of intertwining stems forms below the water surface. Flowering is in early summer.
  • For further help in identifying egeria, search the Dennis Morris Weeds and Endemic Flora database for egeria 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.

Egeria in Tasmania

  • Egeria is recorded as an occasional weed of ponds and slow moving streams in Tasmania (see map). Egeria is also occasionally found in aquaria.
  • Egeria 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 egeria in your area?

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

See also
Egeria Control Guide
Herbicides for Aquatic Weed Control
Statutory Management Plan for Egeria
Weed Links and Resources

Other useful links
Pest Genie

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