Noxious weeds are found everywhere in King County—in urban, suburban and rural areas; on developed and undeveloped land, farmland, forests and other natural open spaces as well as in lakes, rivers, streams and Puget Sound.  Some of the noxious weeds found in King County include:

• Giant hogweed - predominantly an urban weed and an escaped garden ornamental, its sap can cause skin blistering and scarring.

• Garlic mustard - one of the worst forest understory weeds in the Great Lakes and Northeastern United States, it is now spreading from urban to rural areas in the Pacific Northwest, threatening woodlands and sensitive habitats.

• Tansy ragwort - likely to infest pastures and roadsides, it has toxins that can be fatal to cows and horses and it reduces pasture quality.

• Spotted knapweed - threatens wildlife habitat, pastures, and grasslands by displacing beneficial species.

• Purple loosestrife - grows in wetlands and along lakes, rivers and streams; it chokes out wildlife habitat and clogs drainage ditches and irrigation canals. Purple loosestrife invades wetlands in 48 states, crowding out native plants and endangering the wildlife that depend on the native plants.

• Parrotfeather - chokes out prime salmon habitat and reduces availability of refuge, exposing salmon to predators.

• Invasive knotweeds - aggressive, hard to control perennials that are destroying riparian habitat in the Pacific Northwest.