Species Information

Variable-leaved watermilfoil Variable-leaved watermilfoil

Variable-leaved watermilfoil
Variable-leaf watermilfoil
Myriophyllum heterophyllum

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Similar Species
  • Most native watermilfoil species

History
  • Native to the southeast and midwest United States
  • First recorded in New England in 1932 in Bridgeport, Connecticut

Characteristics
  • Rooted perennial aquatic plant
  • Forms dense beds
  • Stems are thick (3mm), robust, and frequently, but not always, red
  • Submerged leaves finely divided (pinnate), resembling a feather, arranged in whorls of 4 to 6 around the stem
  • Emergent floral spike produces long, slender leaves with serrated margins that look nothing like the submerged leaves
  • Flowers grow from base of emergent leaves

Habitat
  • Slow-moving waters, including lakes and ponds, but occasionally rivers
  • Grows in a wide range of temperatures and water conditions, including acidic and calcium-rich lakes
  • Water depths to 8 ft (2.4 m), deeper if water clarity is adequate

 


Known Distribution in the Northeast
  • As far north as Maine and Quebec

 


Impacts
  • Can form dense mats that shade and crowd out native aquatic plants
  • Thick growth can impair recreational uses of waterways, including boating, swimming, and fishing
  • Degrades habitat of fish and other wildlife
  • May provide breeding areas for mosquitoes

Variable-leaved watermilfoil
Variable-leaved watermilfoil
Variable-leaved watermilfoil (Myriophyllum heterophyllum)
Graves Lovell, Alabama Dept. Conservation and Natural Resources
Variable-leaved watermilfoil
Variable-leaved watermilfoil
Variable-leaved watermilfoil