Eurasian Watermilfoil

( Myriophyllum spicatum )

QUICK IDENTIFICATION

  • 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

Aquatic
Stem
Leaf
Bloom
Mature
Mature

Weed Information

Type Information
Toxicity Non-toxic
Control Diver hand-pulling/dredging, aquatic herbicide and installation of bottom barriers. Contact your County Weed District or local applicator for more information.
Habitat Lakes, rivers and sloughs
Root Slender, fragile and extensive root system
Leaf Shape Thread-like with four leaflets arranged around the stem.
Lifespan Perennial; two years or longer
Priority 2A Weed Common in isolated areas of Montana.
Similar Looking Plants Northern native milfoil and parrotfeather
Important Information Forms 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.
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