Dear Friends of Maine Lakes, Thank you for visiting our Interactive Field Guide! Though the primary content pertaining to species identification in this Guide is—for the most part—still correct and useful, the site itself is no longer fully-functional (nor able to be updated). The entire Guide will soon be replaced by a new, expanded website-version of the Maine Field Guide to Aquatic Phenomena. So please stay tuned! Thank you for your patience!

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Milfoil comparison table
Milfoil comparison table

INVASIVE WATER-MILFOILS
Myriophyllum species

NOT NATIVE TO MAINE - INVASIVE
NOTE: All leafy milfoils display a wide range of vegetative variability. Any milfoil found in Maine waters should be considered “suspicious” until a positive identification has been confirmed by someone with the appropriate expertise.



Eurasian Milfoil colony
Eurasian water-milfoil in-situ

Eurasian Water-milfoil (Myriophyllum spicatum): Eurasian water-milfoil is an extremely well adapted plant, able to thrive in a wide variety of environmental conditions. It grows well in still and flowing waters, and can survive under ice. Variable water-milfoil grows rooted in water depths from 1 to 5 meters on various substrates including organic muck, silt, sand and gravel. Plants stranded on dewatered shorelines form erect spikes known as “terrestrial morphs.” The morphs, resembling miniature pine trees, will remain in this land-adapted form until the waters return, at which time they will “morph” back into submersed aquatic plants.





Variable Milfoil colony
variable water-milfoil in-situ

Variable Water-milfoil (Myriophyllum heterophyllum): Variable water-milfoil is a submersed, aquatic plant with branching stems emerging from dense, spreading roots. Featherdivided leaves are arranged in densely packed whorls. (Leaves along lower portions of the stem may not be in perfect whorls, i.e., some leaves may be slightly offset.) There are generally 4 to 6 leaves per whorl and 5 to 14 pairs of thread-like leaflets on each leaf. The dense leaf arrangement gives this plant a bottle brush appearance. Stems may be green and slight, but most often they are thick, robust and reddish in color (even bright red). Flowers and bracts are arranged in whorls on an emergent flower spike. The tiny white flowers occur in the axils of the bracts. The bracts are bladeshaped, serrated, and more than twice the length of the flower. Winter buds (or turions) are formed in the fall at the base of the stems or on the rhizomes.



Hybrid Variable Milfoil stems
Hybrid variable water-milfoil stems

Hybrid Variable Water-milfoil (Myriophyllum heterophyllum X M. laxum): Hybrid Variable water-milfoil is native to parts of the United States, but not native to New England. Variable water-milfoil is present in Maine and all New England states except Vermont. A hybrid of this species (M. heterophyllum x M. laxum), depicted on the following page, has also been confirmed in Maine.Featherdivided leaves are arranged in densely packed whorls. (Leaves along lower portions of the stem may not be in perfect whorls, i.e., some leaves may be slightly offset.) There are generally 4 to 6 leaves per whorl and 5 to 14 pairs of thread-like leaflets on each leaf. The dense leaf arrangement gives this plant a bottle brush appearance. Stems may be green and slight, but most often they are thick, robust and reddish in color (even bright red). Flowers and bracts are arranged in whorls on an emergent flower spike. The tiny white flowe



Parrot Feather colony
Parrot Feather in-situ

Parrot Feather (Myriophyllum aquaticum): Parrot Feather is native to parts of the United States, but not native to New England. Variable water-milfoil is present in Maine and all New England states except Vermont. A hybrid of this species (M. heterophyllum x M. laxum), depicted on the following page, has also been confirmed in Maine.Featherdivided leaves are arranged in densely packed whorls. (Leaves along lower portions of the stem may not be in perfect whorls, i.e., some leaves may be slightly offset.) There are generally 4 to 6 leaves per whorl and 5 to 14 pairs of thread-like leaflets on each leaf. The dense leaf arrangement gives this plant a bottle brush appearance. Stems may be green and slight, but most often they are thick, robust and reddish in color (even bright red). Flowers and bracts are arranged in whorls on an emergent flower spike. The tiny white flowe


Look Alikes: May be confused with bladderworts, hornworts, mermaid weeds, water crowfoots, and other leafy water-milfoils.


 

Click Images for Larger Version
Variable Water Milfoil Variable Water Milfoil Colony Variable Water Milfoil terrestrial morph Variable Water Milfoil Flower Variable Water Milfoil Flower Spike Variable Water Milfoil Variable Water Milfoil Flower Spike



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