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Variable-leaf Watermilfoil

Photo by Meghan Johnstone, APIPP

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Common Name: Variable-leaf watermilfoil
Scientific Name: Myriophyllum heterophyllum
Origin: Various regions of the U.S.


Variable-leaf watermilfoil is a submerged perennial that looks like many native plants, including native milfoil species. It has 4-6 feathery leaves whorled around the stem, but some leaves can be alternating. Leaves are divided into 7-14 pairs of leaflets. Dense leaf arrangement gives this plant a bottle brush appearance. Stems are thick and reddish-brown. In mid to late summer, blade-like, serrated leaves with small, reddish pink flowers form an erect spike that emerges from the water.


This plant grows in a variety of depths, sediment types, and flowing conditions but typically is found in shallow bays and coves.


Plant fragments, which break off easily, can be transported from lake to lake on boat trailers or fishing gear. These fragments can start new populations, which form dense mats that degrade habitat and reduce recreational access.


Once milfoil becomes well-established within a waterbody, it is very difficult to remove. A variety of control methods to manage milfoil infestations include physical, mechanical, biological, and chemical techniques.

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