Variable Watermilfoil
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.
Common Name: Variable watermilfoil
Scientific Name: Myriophyllum heterophyllum
Native Range: Various regions of the U.S.
Background
Variable watermilfoil is a submerged perennial that looks like many native plants, including native milfoil species. It has four to six 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.
Habitat
This plant grows in a variety of depths, sediment types, and flowing conditions but typically is found in shallow bays and coves.
NYS Distribution Map
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Identification
Variable watermilfoil has four to six feathery leaves in whorls that occasionally alternate on the stem. The stem itself is robust and reddish-brown. Emergent flower spikes have serrated, lance-shaped leaves.
Impact
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.
Prevention and Control
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.
