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 preventing Lagarosiphon from becoming a major problem in Queensland.

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 detections. 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.

You must take reasonable action to minimise the risk of spreading Lagarosiphon to ensure the situation isn't worsened.

You must report all sightings to Biosecurity Queensland within 24 hours.

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 known to occur 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.


  • Before undertaking any preventative or control actions, contact our Customer Service Centre.
  • 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.
  • You must not keep, move, give away, sell or release into the environment. Penalties may apply.
  • You must not take any action reasonably likely to exacerbate the biosecurity threat posed by lagarosiphon.
  • You must take any action that is reasonably likely to minimise the biosecurity threat posed by lagarosiphon.
  • You must report all sightings to Biosecurity Queensland within 24 hours.

Further information