Noxious Weeds Named for King County

  • Written by Valley View Staff

Weeds are more than a nuisance in the garden. Some weeds are invasive and harmful to people, crops, animals and the environment. It is those weeds that the King County Noxious Weed Control Board tries to keep under control and even eliminate.

At the most recent Weed List Hearing of the board, poison hemlock was added to the list of regulated weeds, with control required on public property and public rights-of-way in cities and unincorporated areas throughout the county. On private property, poison-hemlock control isn’t required but it is strongly encouraged, especially where there is potential for exposure (such as farms, schools or gardens) or where there is a risk of plants spreading to other properties.

Also new to the Weeds of Concern list this year are silver lace vine and rough chervil, which are non-native plants that have become invasive throughout King County.

Poison-hemlock is very toxic, spreads quickly by seed, and poses a public health threat, especially in areas with public access where people might confuse it with edible plants that it closely resembles. When young, it looks similar to carrot plants but later in the season, it shoots up to as high as 10 feet with tiny white clusters of flowers, purple-red spots on hairless stems, and lacy leaves that smell musty.
Silver lace vine is a climbing vine that looks pretty by can overtake trees and other vegetation. Rough chervil is of the carrot family, but is toxic and quickly takes over an area.

For help identifying these weeds or any other noxious weed, the Weed Control Board offers the King County Connect ap to download that not only shows photos and information about each plant on the lists, it also allows users to snap a picture and location of a plant they suspect is invasive or harmful, and the weed board will follow up.

For weeds that are regulated, a noxious weed specialist will visit the location and notify the appropriate agency or property owner to make sure the weeds are controlled. For weeds that aren’t regulated, the data will be shared with agencies or partners working on invasive weed control in that area.
Identification and control information is available on the King County website or by contacting the Noxious Weed Control Program at 206-477-9333 or This email address is being protected from spambots. You need JavaScript enabled to view it..

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