Eurasian water milfoil

Alert

Be on the lookout for Eurasian water milfoil and report any sightings immediately.

Reporting options

Native to Eurasia and northern Africa, Eurasian water milfoil is a submerged invasive aquatic plant that can grow quickly and invade waterways. It has not been found in Queensland so far but could become a major pest here if introduced. It is a prohibited invasive plant under the Biosecurity Act 2014.

Scientific name

Myriophyllum spicatum

Similar species

  • Native Myriophyllum ssp., Ceratophyllum demersum

Description

  • It is a submersed aquatic plant.
  • Emergent flower heads are orange to red.
  • Leaves are dissected, 'feathery', in whorls of 4, and contain 12–21 leaflets.
  • Long stems form surface-reaching mats.
  • Plants form turions (dormant, detached buds) for overwintering.
  • Rhizomes root to 10m depth, can grow 3–5m to surface.

3D model

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Habitat

  • Prefers slow-flowing and standing water bodies.
  • Can grow in fresh and saline water.
  • Grows well in nutrient-rich water.

Distribution

  • Not known to occur in Queensland.

Life cycle

  • Begins growth in spring with increasing water temperature. Achieves maximum growth in water temperatures above 18°C.
  • Flowers in summer once stems reach water surface. Is pollinated by wind and insects.
  • Plants fragment after flowering and die back to rhizomes towards winter. Rhizomes resprout in spring.

Impacts

Environmental

  • Grows quickly in calm water bodies such as reservoirs and dams, eventually blocking waterways.
  • Displaces native aquatic plants and reduces biodiversity.
  • Can affect water quality when infestations are dense.
  • Creates favourable mosquito habitat.

Social

  • Impedes recreational activities such as waterskiing and fishing.
  • Interferes with infrastructure such as irrigation.
  • Poses danger for swimmers, who can become entangled.

How it is spread

  • The plant propagates through seeds and stem fragments.
  • Seeds can be spread by waterbirds.
  • Fragments are spread by water currents and humans—this is the main way the plant spreads.

Control

Herbicide control

  • Controlled with herbicides overseas (2,4D, Diquat, endothall, copper, fluridone).

Biological control

  • No known biological control agents.

Legal requirements

  • You must not:
    • keep it
    • move it
    • give it away
    • sell it
    • release it into the environment.
  • If you do any of these, penalties may apply.

  • You must not take any action that is reasonably likely to exacerbate the biosecurity threat posed by Eurasian water milfoil.
  • You must take any action that is reasonably likely to minimise the biosecurity threat posed by Eurasian water milfoil.
  • You must report any sightings immediately using 1 of these methods:

Further information