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W2O!: Eurasian Watermilfoil



Eurasian Watermilfoil (Myriophyllum spicatum)
Eurasian watermilfoil.  Robert Johnson, Cornell University.  Ruthanna Hawkins, Cayuga Lake Watershed Network.  Used with permission.
Eurasian watermilfoil. Robert Johnson, Cornell University. Ruthanna Hawkins, Cayuga Lake Watershed Network. Used with permission.
Eurasian watermilfoil drawing.  University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master.  Used with permission.
Eurasian Watermilfoil Drawing, University of Florida, Center for Aquatic and Invasive Plants Line Drawing DVD Master. Used with permission.
  • Native to Europe/Asia
  • Reported in North America in late 1800s
  • Plant Characteristics
    • Submersed rooted perennial plant that forms dense mats on the surface
    • Can grow up to 20 feet long
    • Feathery, blunted-ended leaves, less than 2 inches long in whorls of 3 to 6 with about 14 to 20 pairs of thread-like leaflets
    • Leaves fall limp when removed from the water
    • Has green or reddish brown to purple branching steams and the shoots near the surface are reddish brown.
    • Has small reddish flowers raised above the water on a spike that often blooms July to August
    • Reproduces from plant fragments
    • Thrives after curly pondweed dies back
    • Inhabits lakes and ponds, fresh and salty water, up to 30 feet deep
    • Inhibits swimming, boating, and water recreation
Eurasian Watermilfoil Map, USGS, Nonindigenous Aquatic Species
Eurasian Watermilfoil Map, USGS, Nonindigenous Aquatic Species

Eurasian watermilfoil Look Alikes

Native Look Alike:  Coontail (Ceratophyllum demersum)
  • Plant Characteristics
    • Free-floating submersed perennial
    • Leaves are forked, in tight whorls of 5-12
    • Leaves tend to be more stiff and bristly than Eurasian watermilfoil
    • Slender, hollow stems can grow to 20 inches
    • Long trailing stems lack true roots, appears to be rooted
    • Good habitat for small invertebrates
    • Provides food for birds as well as food and shelter for fish
    • Coontail, Kelly E. Somerlot, Onondaga County CCE
      Coontail, Kelly E. Somerlot, Onondaga County CCE
      Closer View Coontail, Kelly E. Somerlot, Onondaga County CCE
      Closer View of Coontail, Kelly E. Somerlot, Onondaga County CCE

      Coontail underwater, Kelly E. Somerlot, Onondaga County CCE Coontail underwater, Kelly E. Somerlot, Onondaga County CCE
Native Look Alike:  Northern (Myriophyllum sibiricum) or Spiked watermilfoil (Myriophyllum exalbescens)
  • Plant Characteristics
    • Submersed, rooted perennial that is entirely submersed except for a mostly bare, floral spike with red-tinted flowers, less than 4 inches long
    • Has leafy purple-brown stems
    • Has whorls of 4-5 feather-like leaves, smaller than a quarter, 5-12 pairs of leaflets
    • Leaflet pairs are shorter on top and longer on the bottom, creating a fir tree shape
    • Leaves tend to be more stiff and bristly than Eurasian watermilfoil

    • Northern watermilfoil, Aquatic Plant Information System (APIS), www.wes.army.mil/el/aqua
      Northern watermilfoil, Aquatic Plant Information System (APIS), www.wes.army.mil/el/aqua