Noxious weeds – we don’t want ‘em

Noxious weeds can come in the form of a beautiful flower, such as the common St. Johnswort (Hypericum perforatum).
Noxious weeds can come in the form of a beautiful flower, such as the common St. Johnswort (Hypericum perforatum), but this plant produces large amounts of persistent seed and spreads easily.

We’re being invaded! By noxious weeds and invasive plants, that is. Each year, landowners and public agencies in Washington state spend millions of dollars to control or eradicate these invaders, which can seriously damage our native species and ecosystems.

What’s the difference between noxious weeds and invasive species? Are both bad?

  • An invasive plant is not native to the area and has a tendency to spread and crowd out other species. Many noxious weeds are also invasive plants.
  • A noxious weed is any plant designated by a federal, state, or county government as harmful to public health, agriculture, recreation, wildfire safety, or property.

How do noxious weeds spread?

Cars, cargo ships, hiking boots, and even bicycle tires can all spread weed seeds, so the more people travel and trade, the more likely we are to accidentally transport weed seeds. Some noxious weeds and invasive plants, like Canada thistle arrived here by accident with early European settlers; others, like Scotch broom, were imported as ornamental plants which then escaped into the wild ­– and innumerable hillsides, vacant lots and pastures.

Wildlife and domesticated animals also can spread weed seeds, either through their digestive systems or in their fur.

You can find out about weeds and other invasive species or report a sighting through the Washington Invasive Species Council either online or by downloading the council’s app for your iPhone or Android.

Invasive species are everyone’s problem. Learn more about what you can do to “weed” out your invasive plants from the Washington Invasive Species Council or the National Invasive Council (

Why not teach kids about invasive species in Washington? The Washington State Department of Agriculture publishes what they call the Invasive Species “Fun Book”, an educational activity book for children focused on the impacts of invasive plants and animals in Washington. 

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