Eurasian Watermilfoil

Eurasian watermilfoil has slender stems up to 2.5 m (8.2 ft) long. The plant is a perennial that grows under the water surface and has feather-like green leaves that circle the stem in groups of four or five. Eurasian watermilfoil blooms in late July and early August and has orange/red flowers that are 4–6 mm long. Flowers are produced in the leaf axils on a spike that can be 5–20 cm long, held vertically above the water surface. 

Eurasian watermilfoil was discovered in Canada in Lake Erie in 1961. Since its first spotting, Eurasian watermilfoil has spread throughout all of the Great Lakes, the St. Lawrence River and inland lakes throughout Ontario. Currently, Euarsian watermilfoil is present in three Canadian provinces: Ontario, Quebec, and British Columbia. 

Eurasian watermilfoil is spread through the transportation of recreational boats, fishing equipment, and any other equipment that can come in contact with this invasive plant. The plant can spread when fragments are attached to equipment and transported to another body of water. It is important to  clean, drain, and dry all outdoor equipment. Find more information on our prevent the spread page.

Eurasian watermilfoil is threatening Canadian waterways by competing directly with native plants and reducing biodiversity. Thick mats of Eurasian watermilfoil prevent other native plants and native fish species from thriving within the ecosystem. 

Eurasian watermilfoil can reduce the amount of oxygen within the ecosystem, making it difficult for other species to survive. In the fall, when large mats of Eurasian watermilfoil die off, the decaying plants can reduce oxygen levels within the water.

Large, thick mats of Eurasian watermilfoil impact recreational activities such as swimming, boating, and fishing. This invasive plant hinders boats from propelling through and often does not provide suitable conditions for fishing.

Learn how to identify Eurasian watermilfoil and avoid accidentally spreading this plant with your watercraft or fishing equipment.

• Learn the key ID features of Eurasian watermilfoil. 
• Avoid infested areas or reduce your speed when travelling near Eurasian watermilfoil infestations. Your propeller can break off fragments and spread the pieces to new areas. New plants can grow from small pieces of the plant.
• Inspect your boat, trailer, and equipment after each use. Remove all plants, animals, and mud before moving to a new waterbody. Learn more about the process of clean, drain, dry. 
• Avoid planting Eurasian watermilfoil in your aquarium or water garden. Aquarium hobbyists and water gardeners should only use native or non-invasive plants and are encouraged to ask retailers for plants that are not invasive.
• Never release unwanted aquarium plants or pets. Return or donate unwanted plants to a garden centre or pet store, or put them in the garbage. Do not put them in the compost or discard them in natural areas. Discarded plants may produce seeds that can sprout.
• If you’ve seen Eurasian watermilfoil report the sighting.

Parrot feather (invasive)

Invasive parrot feather is common in the aquarium trade. It has leaves that rise above the surface of the water, while only the terminal flower spike of Eurasian watermilfoil emerges from the water. Parrot feather is a prohibited species under the Ontario Invasive Species Act, meaning it is illegal to import, possess, deposit, release, transport, breed/grow, buy, sell, lease or trade this species in Ontario.