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Adirondack Park Agency Adirondack Nature Conservancy Paul Smith's College NYS Department of Environmental Conservation Adirondack Park Agency Adirondack Nature Conservancy
 

Plant Identification

Eurasian Watermilfoil
(Myriophyllum spicatum)


Fact sheet
Click images for larger view
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Eurasian Watermilfoil
Eurasian watermilfoil is easily confused with other submerged aquatic plants, especially due to the presence of five native watermilfoils frequently found throughout the Adirondack region.

All of the Adirondack's common native watermilfoils are submersed aquatic plants. The leaves are feather-like, finely divided, and either whorled or alternately arranged on the stem. Flowers are produced in the leaf axils (where the leaf meets the stem) or on emergent spikes. (Native Milfoil comparison fact sheet).

Use the identification techniques and images below to help distinguish Eurasian watermilfoil from other aquatic plants.

 
** These techniques usually but not always hold true due to the
variability in the growth and appearance of Eurasian watermilfoil.*


Eurasian Watermilfoil Plant Characteristics
Photos provided by Gordon Keyes © 2002

  
 
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 Eurasian watermilfoil is a submerged aquatic plant that when reaching the surface of the water, grows horizontally creating a mat.
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 The stem can range from pale pink to red to reddish brown with feathery leaves.
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 Leaves are divided into leaflets usually numbering greater than 9 per leaf. The ends of the leaves form a blunt tip, appearing snipped. Between 3 to 5 leaves grow in a whorled pattern around the stem.
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 The growing tips of the plant are often bright red.
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 The flowering structure, usually present in late summer, is the best characteristic to identify Eurasian watermilfoil. The flower is an emergent spike, up to twice the width of the stem. The red flowers are larger than the green bracts (click on image). Except for the native Northern watermilfoil, other native watermilfoils have flowers that are smaller than the green bracts, or they lack emergent flowering spikes.
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 When Eurasian watermilfoil is out of water, the leaves lose their rigidity and often collapse around the stem.
 

Many native plants have characteristics that resemble those of invasive aquatic plants. To identify an aquatic plant, begin by observing leaf types and how the leaves are arranged on the plants. Also note any other structures the plant may have such as flowers, fruits, bladders, and root structures.

'Common Look-Alike Plants' fact sheet
 
Invasive and Native Aquatic Plant Comparison
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Invasive Eurasian watermilfoil
and Native watermilfoil
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Native Elodea		 Click to Enlarge
Native Coontail		 Click to Enlarge
Invasive Eurasian watermilfoil
and Native Bladderwort