Eurasian Watermilfoil, Myriophyllum spicatum

Immersed perennial

Depth: between 0.5 and 10 m but especially between 0.5 and 3.5 m; roots at the water body floor and grows toward the surface, where it branches and forms a thick carpet

Leaves: verticillate, usually in fours, well-divided, feather-shaped, in excess of 12 segments on each side of the leaf, often truncated at the apex

Flowers: spears of rosy or whitish petals

Lakes, rivers, ponds, ditches, irrigation and navigation canals

Eurasian Watermilfoil is native to Europe, Asia and North Africa. Indications are that the species was introduced to this continent by ballast water spillage into Chesapeake Bay. The plant then spread rapidly, with fisherman, pleasure craft, marine life and aquarium plant commerce all contributing greatly. In Canada, Eurasian Watermilfoil was first noticed in Ontario and Québec in the 1960s, when it quickly became noxious in numerous locations.

Measures taken to counter this plant have thus far shown only modest success. Even if the situation seems to have stabilized in many locations along the St. Lawrence River, it is highly likely that the invasion continues in the Laurentian lake and Appalachian regions.

The capacity of Eurasian Watermilfoil to quickly propagate vegetatively gives it an obvious advantage over other species. It easily replaces indigenous immersed plants and benefits from changes to the environment through dredging and eutrophication. Dense Eurasian Watermilfoil stands also seem to be harmful to fish species such as Lake Trout, by changing environmental conditions in spawning areas. Moreover, Watermilfoil seriously curtails recreational activities such as swimming and boating.

A variety of chemical, mechanical, physical and biological measures have been employed in efforts to eradicate Eurasian Watermilfoil, with not much success, but you can make a difference locally by containing its spread.

Similar Species:

Eurasian Watermilfoil can be confused with the following species:

• Northern Water Milfoil (Myriophyllum sibiricum): indigenous species


• Common Bladderwort (Utricularia vulgaris): indigenous species


• All Water Milfoils (Myriophyllum sp.): indigenous species


• Common Hornwort (Ceratophyllum demersum): indigenous species


• Parrot’s Feather (Myriophyllum aquaticum): alien species


• Carolina Fanwort (Cabomba caroliniana): alien species

Alternative species:

Here are a few suggested plants you can use in ecologically sound plantings:

• Common Hornwort (Ceratophyllum demersum)


• Canadian Waterweed (Elodea canadensis)


• Water Celery (Vallisneria americana)

Follow this link to see photos of these species.

1. Fédération Ontarienne des pêcheurs et chasseurs, 2000. Les espèces aquatiques invasives. Un guide pour les amateurs de jardins d’eau et d’aquariums. Partenariat Environnement Canada, Pêche et Océans Canada et le Ministère des Ressources naturelles de l’Ontario.

2. Environnement Canada. Service canadien de la faune : Myriophylle à épi (Myriophyllum spicatum L.) http://www.cws-scf.ec.gc.ca/publications/inv/...

3. Environnement Canada. Infos Saint-Laurent : Myriophylle à épi (Myriophyllum spicatum L.)
www.qc.ec.gc.ca/CSL/inf/inf037_f.html

4. Integrated Taxonomic Information System (ITIS),
http://www.itis.gov/servlet/SingleRpt/SingleR...

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