Elodea canadensis

Elodea

Family: Hydrocharitaceae

Origin: North America

Sprigs of elodea against a white background.
Forms dense underwater stands shading out smaller native species.

Regional Pest Management Plan (RPMP) status

  • Aotea — Exclusion
  • Whole region — Sustained control
  • Hauraki Gulf Controlled Area Notice pest

View more about the RPMP statuses

General description

Submerged, bottom-rooting freshwater, aquatic < 5 m tall. Leaves are in whorls of three. Flowers are small, white/purple, five-petalled and borne at water’s surface November – January.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell elodea on Aotea/Great Barrier Island group, or outside of secure containment within the Auckland region.
  • You must not plant elodea on Aotea/Great Barrier Island group.
  • You must not plant elodea outside of secure containment within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
  • You must destroy any elodea on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

If you see elodea anywhere on Aotea/Great Barrier Island group, please report it to Auckland Council at pestfree@aucklandcouncil.govt.nz.

Habitats

Still and slow-moving water bodies < 10 m deep.

Dispersal

Vegetative spread from stem fragments. Human-mediated dispersal through contamination of machinery and fishing equipment and deliberate releases.

Impact on environment

Can reduce flow velocity and impede gas exchange in freshwater ecosystems, lowering dissolved oxygen levels and increasing sedimentation. May impede water flow in drains, exacerbating flooding.

Control

Site Management

Very difficult to control once established.

Recommended approaches

Do not attempt to undertake control of this species on Aotea/Great Barrier Island group. Please report to Auckland Council if seen on Aotea/Great Barrier Island group.

Physical control

Method: Pull out.

Plant parts requiring disposal: All parts.

Disposal options: Remove to greenwaste or landfill if practical.

Biocontrol

Biocontrol is currently not available for this species.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Close up of elodea from the top.
Leaves are bright green leaves occurring in whorls of three.