Haloragaceae - watermilfoil family
 

WeedsPoisonous PlantsHay Fever
Gerald A. Mulligan (Agriculture Canada, Ottawa, retired)
Myriophyllum spicatum L., Eurasian water-milfoil, myriophylle en Úpi
A submersed perennial aquatic herb introduced from Eurasia. Spreads and becomes established by seeds, running rhizomes, and most often by stem fragments. Known to be present in the Pontiac River below Washington D.C. prior to 1881 (Ward, L. F, 1881, Bull. U. S. Nat. Mus. No. 26). It was probably first introduced there in ballast discarded from ships. Water-milfoil now grows, in water from 3 to 30 feet (1 to 10 meters) deep, from Florida to Quebec and Ontario in the east, and from California to British Columbia in the west. It is often introduced from one body of water to another by plant fragments adhering to boats and other means of transport. Once established, water-milfoil often forms a dense mat of vegetation that inhibits all kinds recreational activities. Water-milfoil has clogged pipes in irrigation canals and water and power intakes. Its establishment also has a very deleterious effect on the biology of the resident flora and fauna. Once established, it is very difficult to eradicate. A very nasty customer.

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Weed Name Photo Weed Name Photo
Eurasian water-milfoil, myriophylle en Úpi Eurasian water-milfoil, myriophylle en Úpi