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Variable-leaf Watermilfoil

Myriophyllum heterophyllum

Variable-leaf Watermilfoil in North America
Variable-leaf Watermilfoil in Southeast US
Close up variable-leaf watermilfoil

variable-leaf watermilfoil drawing
emersed variable-leaf watermilfoil
floating variable-leaf watermilfoil

variable-leaf watermilfoil being held
variable-leaf watermilfoil under water
variable-leaf watermilfoil leaves close up

USDA, NRCS. 2018. The PLANTS Database (http://plants.usda.gov, 28 March 2018). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Illustration courtesy of University of Florida/IFAS Center for Aquatic and Invasive Plants. Used with permission.

What is Variable-leaf Watermilfoil?

Physical Characteristics

Leaves:

  • Whorls of 4-6

Submersed Leaves:

  • 0.78-2 inches long
  • 0.78 inch spaces in between leaves

Emersed Leaves:

  • Firm
  • Sword- or elliptical- shaped
  • 1.19 inches long
  • 0.05 inches wide

Flowers:

  • Whorls of 4-6
  • Jagged edges
  • About 0.05 inches long
  • Up to 0.05 inches wide
  • Petals 0.05-0.13 inches long
  • 4 anthers, up to 0.09 inches long

Spikes:

  • Emersed
  • Up to 1.5 feet long, although usually shorter

Fruit:

  • Disk-shaped
  • 0.05-0.13 inches long and wide

Stem:

  • Thick

Where Does it Grow?

Variable-leaf watermilfoil can be found in ponds, lakes, and streams.

Is it Invasive?

Although variable-leaf watermilfoil is native to North America, it is an aggressive invader because of its tremendous growth rate. Variable-leaf watermilfoil can completely takeover shallow ponds.

Pros and Cons of Variable-leaf Watermilfoil

Variable-leaf watermilfoil seeds and foliage are consumed by some ducks. Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates. These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc.). After aquatic plants die, their decomposition by bacteria and fungi provides food (called “detritus”) for many aquatic invertebrates.

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Photo Credits: The majority of the aquatic plant line drawings are the copyright of the University of Florida Center for Aquatic Plants (Gainsville). They are used with permission.

Aquatic plant photographs were provided by David Bayne, Jim Davis, Kelly Duffie, Billy Higginbotham, Michael Masser, John Clayton, Chetta Owens, Diane Smith, Joe Snow, Don Steinbach, Bridget Robinson Lassiter and Peter Woods.

You may use these photos, so long as you give credit to AquaPlant.

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