Elodea (Elodea canadensis)

Elodea is a submerged aquatic plant found in slow-moving and stationary water bodies.


How does this weed affect you?

Elodea forms dense mats under the water that outcompete native plants, reducing food and habitat for fish and other aquatic animals. It also makes makes recreational activities such as swimming, fishing and boating difficult.

What does it look like?

Leaves are 0.5–1.5 cm long, 0.2–0.5 cm wide, and occur in whorls of 3 (rarely 4). They are bright green and bend down slightly. 

Inconspicuous flowers occur on white thread-like stems, and have 3 petals. Only male flowers occur in Australia.

There are a number of similar looking species, including: 

  • Egeria (Egeria densa): leaves in whorls of 4–5, crowded; larger flowers (2 cm wide) and leaves (4 cm long)
  • Hydrilla (Hydrilla verticillata): leaves in whorls of 3–8; larger leaves (up to 4 cm long), almost straight, serrated, dull green
  • Lagarosiphon (Lagarosiphon major): leaves in alternate spirals; curve downwards

Where is it found?

Elodea is found in slow-moving and stationary water bodies, coastal rivers and creeks, especially in colder areas in NSW, Vic and Tas. It has been a major problem in constructed waterways of northern Vic and south-western NSW.

In NSW, most infestations are in the Murray and South East regions. Plants have also been found growing in the Greater Sydney, Hunter, Riverina, North Coast and Northern Tablelands.

How does it spread?

Spread occurs by fragments. Elodea does not seed as only male flowers are found in Australia. Stems readily break into pieces which are easily transported in water.

What type of environment does it grow in?

Elodea thrives in temperate zones, can withstand freezing and grows rapidly when temperatures exceed 15 °C. Elodea does not thrive in iron-deprived water and has a high light requirement for optimum growth.

More information

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Herbicide options

Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.

Diquat 200 g/L with (Various products)
Rate: 5 L per Megalitre of water
Comments: Apply by injection below the surface or as a surface spray. Follow label as for pond weeds.
Withholding period: Do not use treated water for human consumption, livestock watering or irrigation purposes for 10 days after application. Do not graze or cut sprayed vegetation for stock food for 1 day after application. See label for harvest withholding periods.
Herbicide group: 22 (previously group L), Inhibition of photosynthesis at photosystem I via electron diversion (PSI electron diversion)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

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For technical advice and assistance with identification please contact your local council weeds officer.

Reviewed 2024