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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

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Why is this species a problem?

Garlic mustard has become Portland’s poster child for plants that overwhelm the landscape by seeding: a single plant can make hundreds of small seeds. Like many weeds, dense patches form along roads, streams and other disturbed areas. Unlike most other species, though, garlic mustard moves from disturbed areas into healthy forest. There it forms dense patches which dominate and displace native wildflowers, tree seedlings, and other native plant species of intact forests. The reduced plant diversity that comes with garlic mustard monoculture means less resources for wildlife, and, ultimately, no new trees.  Because garlic mustard seeds are numerous and very small, they are easily spread through a number means.

seeds spread by tires and machineryseeds spread by clinging to hiking bootsseeds spread by running waterseeds spread by clinging to animal furIn addition, the roots of garlic mustard are thought to produce a toxin that kills soil fungi many plants depend on. The seeds are about the size of a grain of mustard and can move around easily. Combine that with these seeds surviving several years in the soil and you have a plant that’s difficult to manage.

garlic mustardgarlic mustard blooming