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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

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Why is this species a problem?

Milk thistle is known to form dense patches that originate in open, disturbed areas. Like other thistles, these plants have persistent root systems and produce large amounts of windblown seed, making management difficult. Milk thistle reduces plant diversity as other species are displaced. Invasions are of particular concern in forage lands, where milk thistle also poses a health hazard to livestock.

seeds spread by clinging to animal furseeds are spread by windseeds spread by clinging to tires