Eurasian Watermilfoil


  • Feathery underwater foliage
  • 12 or more pairs of leaflets
  • Leaves collapse around the stem when removed from the water
  • Mature leaves in whorls of four around the stem
  • Length up to 15 feet

Weed Pictures

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Weed Information

ControlDiver hand pulling/dredging, aquatic herbicide and installation of bottom barriers. Contact your County Weed District or local Applicator for more information.
HabitatLakes, rivers and sloughs.
RootSlender, fragile and extensive root system.
Leaf ShapeThread-like with four leaflets arranged around the stem.
LifespanPerennial; two years or longer.
Priority 2A WeedCommon in isolated areas of Montana.
Similar Looking PlantsNorthern native milfoil and parrotfeather.
Important InformationForms very dense mats of vegetation on the surface of the water; extremely rapid reproduction and can infest an entire lake within two years of introduction to the system. A plant fragment with 2 nodes (areas where leaves are located) can start a new infestation.