Milfoils - Myriophyllum spp.

There are several water milfoils found in Massachusetts including Eurasian milfoil (exotic), variable milfoil (exotic), and native low water milfoil.

Eurasian milfoil (Myriophyllum spicatum)

Eurasian milfoil is a very hardy species and has established itself in a wide range of aquatic habitats. It over-winters in the frozen lakes of northern climates and can also survive in shallow warm water bodies. Grows under a wide range of water chemistry conditions and is found in oligotrophic (low nutrient) and eutrophic (nutrient rich) lakes and can tolerate waters with up to 10 parts per thousand of salt, and a wide range of temperatures and pH. Prefers slow moving waters including lakes and ponds but occasionally exists in rivers.

Identification of Eurasian milfoil
(Milfoil species can be very difficult to distinguish.)

  • Submerged, rooted plants
  • Leaves are finely dissected, appearing feather-like (not accompanied by small bladders or sacs (see descriptions of bladderworts)
  • Leaves are blunt-ended as if cut by a scissor and can be up to 2” long
  • Each leaf has 11 leaflets per side
  • Leaves in whorls of 3-6
  • Stems are reddish, plants appear red tipped
  • Flowers are small and reddish on a distinct emergent stalk (form in July and August)

Eurasian milfoil

Variable milfoil (Myriophyllum heterophyllum)

Variable milfoil is an aquatic rooted, submerged non-native plant with a “raccoon-tail” or pipe
cleaner appearance. Variable Milfoil can form dense mats at the water surface and can grow in the photic zone, in up to 10 feet of water. During late summer a 4-6 inch emergent bract develops, protruding above the water surface. The small bright green leaves on the bract are oval and are both serrated and non-serrated. (The lower female section of the bract has serrated leaves, and the upper male portion has smooth margins).

Identification of variable milfoil

  • Submerged, rooted plants
  • Leaves are finely dissected, appearing feather-like
  • Leaves have 6 – 12 segments
  • Not accompanied by small bladders or sacs (see descriptions of bladderworts)
  • Thick red stem and stiff emergent bract with flowers (late summer)

Variable milfoil

Similar-looking plants
Variable Milfoil is often confused with the native Coontail (Ceratophyllum) and Low Water Milfoil (Myriophyllum humile).

The leaves of Coontail are branched (the stem continues to fork and split) where as Variable Milfoil has leaves that are feathered (like a bird feather). Coontail leaflets have small “teeth” along the back edge that can be distinctly felt.

Although both the native Low Water Milfoil and exotic Variable Milfoil have feathered leaves, the native Low Water Milfoil has very limp leaves that are alternate, not whorled. Low Water Milfoil does not form a stiff emergent bract with variable-type leaves, instead it develops a delicate emergent potion and smooth fruits at the leaf axils.

Because milfoils regrow from plant fragments, they should NOT be pulled so that they fragment. Potential treatments include chemical treatment, bottom barriers, and pulling with fragement barriers in place. If you suspect an infestation in your area contact your local Conservation Commission and the Mass Lakes and Ponds Program for technical assistance.

Washington Dept. of Ecology description
Washington Dept.of Ecology treatment recommendations