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Have you seen Lagarosiphon?

Be on the lookout for Lagarosiphon and report it to Biosecurity Queensland. Early detection and reporting are the key elements in controlling Lagarosiphon.

Call us on 13 25 23.

Native to southern Africa, lagarosiphon is a submersed aquatic plant that invades water bodies, out-competes native water plants, and can affect native fish and waterbirds.

Lagarosiphon has naturalised in New Zealand and parts of Europe, but Australia currently has no known infestations. The main threat here is release from aquariums into dams and creeks. Responsibility lies with hobbyists, aquatic plant nurseries and pet shop suppliers not to introduce lagarosiphon into Queensland.

Lagarosiphon is a prohibited invasive plant under the Biosecurity Act 2014.

Scientific name

Lagarosiphon major

Other names

  • Oxygen weed, African elodea, curly water weed

Similar species

  • Elodea canadensis, Egeria densa


  • Aggressive perennial submersed aquatic plant with branched, brittle stems up to 5m long.
  • Can grow surface-reaching mats of up to 4m from bottom of water body.
  • Leaves are stiff, curled backwards, alternately arranged in spiral form.


  • Inhabits still and slow-flowing water bodies.
  • Prefers clear water due to high light requirements.
  • In clear water, can live up to 6.5m below surface.
  • Grows well on silty or sandy beds with low nutrient levels.


  • Not currently found in Queensland.

Life cycle

  • Under suitable conditions, forms large, surface-reaching mats throughout the year.
  • Male flowers break from plant and float towards female flowers, which remain attached to stem by long, thin, filament-like tube.
  • Predominantly reproduces from stem fragments in native and introduced range.
  • Flowering or regeneration by seed has not been observed in Australia.

Affected animals

  • Native aquatic animals



  • Invades dams, lakes and streams.
  • Affects native fish and waterbirds when growth becomes dense and restrictive.
  • Out-competes native aquatic plants and forms mono-specific stands.


  • Interferes with power generation and irrigation infrastructure by blocking intake systems.
  • Interferes with recreational activities such as boating, fishing and swimming.

How it is spread

  • Mainly spread by humans through boat trailers and fishing gear.
  • Also spread by water movement: stems break at node, float downstream, produce new infestations.


  • Treat weed infestations when small.
  • Remove underground stems and broken plant pieces to prevent regrowth.

Biological control

  • No known biological control agents.

Legal requirements

  • Lagarosiphon is a prohibited invasive plant under the Biosecurity Act 2014.
  • It must not be given away, sold, or released into the environment without a permit.
  • The Act requires that all sightings to be reported to Biosecurity Queensland within 24 hours.
  • By law, everyone has a general biosecurity obligation (GBO) to take all reasonable and practical steps to minimise the risk of Lagarosiphon spreading until they receive advice from an authorised officer.

Further information