Photo Credit: Alison Fox, University of Florida, Retrieved from Bugwood.org (Image Number: 1624031), used under CC BY 3.0 US, modified from the original
Common Name: Eurasian Watermilfoil
Scientific Name: Myriophyllum spicatum
Habitat: open water
Provincial Designation: Prohibited Noxious
Prohibited Noxious weeds are plant species designated in the Alberta Weed Control Act. Prohibited noxious weeds must be destroyed when found, meaning all growing parts need to be killed or the plant's reproductive mechanisms need to be rendered non-viable.
Eurasian Watermilfoil originates form Eurasia and Africa and came to North America in the ballast of ships.
This plant can form large, floating mats in shallow water. These mats can become so dense that they shade-out native aquatic plants. Plant fragments can attach to boats, trailers, or animals and be moved from one body of water to another. A single segment of stem or leaf can form a new colony.
The flowers of this aquatic plant are tiny (only up to 3 mm wide), white, yellow or pink in colour and are arranged on a spike that rises 5-10 cm above the water.
The green, sometimes grey-green leaves grow in whorls of four around the stem. The leaves are pinnate, having more than 12 pairs of fine, hair-like leaflets.
When leaving any water source, Clean, Drain and Dry all boats and trailers!
Can Be Confused With ...
Northern Milfoil — Myriophyllum sibiricum — the native species leaves are stiff and retain their shape out of the water, unlike Eurasian water milfoil. The two species can hybridize.
Learn more about this species:
See Fact Sheet - Alberta Invasive Species Council