Eurasian water milfoil (Myriophyllum spicatum)

If you see this plant contact your council weeds officer, the NSW Invasive Plants & Animals Enquiry Line 1800 680 244 or email



Eurasian water milfoil is a highly aggressive and invasive submerged aquatic weed that can spread rapidly. It forms a dense stand that shades out and replaces all other aquatic plants, seriously impacting on native plant and animal life. Dense mats also interfere with other uses of water bodies such as recreation and irrigation.

Eurasian water milfoil prefers lakes, ponds, shallow reservoirs and slow moving water, but will also grow in fast moving water.


Eurasian water milfoil is native to Europe, Asia and northern Africa. It is now naturalised and a major weed of lakes and reservoirs in Canada and the USA. It is also considered to be an invasive weed in its native range. This species has not been recorded as present in New South Wales (NSW) or elsewhere in Australia. If introduced, it has the potential to become a major weed of dams, lakes and reservoirs.


Eurasian water milfoil spreads mostly via plant fragments. During the growing season plants automatically fragment, often developing roots before they separate from the parent plant. Water movement and human activities may also cause fragmentation.

Fragments are spread over long distances by water currents and are mainly dispersed between water bodies by boating and fishing activities.

Eurasian water milfoil plants can die back to their base during winter, reshooting in spring.


Eurasian water milfoil is a submerged perennial plant. Stems are rooted at the base and grow towards the surface. It can grow in water from 0.5 to 10 m deep, but most commonly at depths up to 3 m deep.

Key identification features

  • Stems are hairless and slender (5 mm) growing up to 7 m long. They are reddish-brown to whitish-pink in colour and branch profusely near the surface to form a dense canopy.
  • Leaves are usually submerged, olive-green in colour, less than 4 cm long and feather-like. They are arranged around the stem in whorls of four and have 5–24 pairs of divisions (usually more than 12).
  • Flowers are small and pinkish with four petals, occurring in whorls of four around the stem. They are held above the water in an erect spike up to 8 cm tall but then lie parallel to the water surface once fruit are set.


It can tolerate and thrive in a range of temperatures and water conditions, including low levels of salinity.


2006 Edition prepared by Rachele Osmond; 2013 Edition prepared by Elissa van Oosterhout; Reviewed by Rod Ensbey


Aiken SG, Newroth PR and Wile I (1979) The biology of Canadian weeds, 34. Myriophyllum spicatum L., Canadian Journal of Plant Science, 59: 201–215

Hosking JR, Sainty G, Jacobs S and Dellow J (in prep.), The Australian WEEDbook.

back to top


Contact your local council weeds officer if you suspect you have found Eurasian water milfoil. Control of Eurasian water milfoil is difficult. Mechanical harvesting can lead to rapid reinfestation due to the plant being fragmented.

Herbicide options

Contact your local council weeds officer for control advice for Eurasian water milfoil (Myriophyllum spicatum).

back to top

Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds (Weed Control) Order 2014 published in the NSW Government Gazette, detailing weeds declared noxious in New South Wales, Australia, under the Noxious Weeds Act 1993. The Order lists the weed names, the control class and the control requirements for each species declared in a Local Control Authority area.

Area Class Legal requirements
All of NSW 1 State Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant

back to top

Stems are densely branched forming a dense canopy.
Stems are densely branched forming a dense canopy. (Photo: Alison Fox, University of Florida,

Leaves are featherlike and whorled around the stem.
Leaves are featherlike and whorled around the stem. (Photo: © Ian Dodkins,

Eurasian water milfoil flower spike.
Eurasian water milfoil flower spike. (Photo: John Somerville, UK)

Line drawing of Eurasian water milfoil
Line drawing of Eurasian water milfoil (Photo: University of Florida)