(Myriophyllum spicatum)
Common Names
Spike watermilfoil, milfoil, EWM
Description
Eurasain water milfoil or EWM is a new invader to Montana, recently found in Noxon and Cabinet Reservoirs in Sanders County. Eurasian water milfoil is an incredibly invasive submersed aquatic plant. Like the native milfoils, the Eurasian variety has slender stems whorled by submersed feathery leaves and when the plant reaches the water’s surface, it curls to lie parallel with the surface. Leaves are 2-4 cm long, feather-like, and arranged in whorls of 4 around the stem. The leaves are thread-like and uniform in diameter. They typically have greater than 14 leaflet pairs per leaf. When or if this plant flowers, tiny flowers produced above the water surface are reddish to pink and only about 4 – 8 centimeters long. Without flowers, EWM is nearly impossible to distinguish from other milfoils and in order to correctly identify this plant, DNA testing must be done.
Habitat
Eurasian water milfoil grows in a diverse range of aquatic habitats, including rivers, reservoirs, canals, lakes, slow-moving streams, and fish ponds.
Currently found in the following counties:
Sanders
IWM
Interesting Facts
In the past, this plant has been sold as an aquarium plant. With severe infestations, EWM halts all forms of recreation on bodies of water due to the dense mats it forms in the water. There have even been reported deaths due to drowning affiliated with this plant. Any fragment of this plant can remain dried for up to seven days and once it hits water, will become viable and spread.
Commonly Confused Plants
- Native Milfoil (left) vs. Eurasian Water Milfoil (right)
- Coontail
Photo Credits: Nina Eckberg, Thomas Woolf, Heidi Sedivy