Eurasian Watermilfoil (Myriophyllum spicatum)

Eurasian Watermilfoil, Myriophyllum spicatum, invasive, plant, aquatic

General: Aquatic green perennial that is submersed in water with finely dissected leaves. It becomes limp when removed from water. 

Height: It can grow up to 4 metres in depth. 

Flowers: The flower can grow up to 20cm above the water and is reddish in colour. 

Leaves/Stems: The leaves are arranged in whorls of four around each node of the stem.  Each leaflet has 14-24 hair-like, paired divisions that resemble feathers. 

Spiked watermilfoil.

There are native milfoils but they have different numbers of leaflet divisions.

Where did it come from? Native to Europe, Asia, and North Africa. 

Where does it grow here? Eurasian milfoil thrives in nutrient rich, slow-moving waters of ponds, lakes, reservoirs, canals, ditches and other waterbodies. 

This invasive milfoil spreads through the release of aquarium contents into ecosystems as well as hitch-hiking on boats, trailers and gear between waterbodies.

Once established, floating plant fragments produced by waves & boaters spread by water.  New plants develop when the fragments sink.

Also reproduces by seed and fragments of roots. It can produce up to 300,000 seeds per plant that remain viable for 20 years.

  • It forms dense stands that shade out native vegetation. 
  • These stands also degrade water quality, clog canals and reduce recreational activities. 
  • Reduces appeal of beaches due to accumulation of plant debris. 
  • Clear all plant material from boats, motors, trailers, and anchors. 
  • Dispose of plants far away from water bodies. 
  • Report suspected new infestations. 
  • Bottom coverings can be placed over new populations to prevent lake-wide infestations. 
  • Root removal by rototilling or hand-pulling. 
  • Always Clean, Drain, & Dry your aquatic gear. 

Oregon Sea Grant. 2014. On the Lookout for Aquatic Invaders: Identification Guide for the West. Oregon State University.

Okanagan Invasive Species Online Website.

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