History and impact
This familiar plant, also known as Scot's Broom, is an invasive flowering shrub that grows commonly throughout the Puget Sound region. Originally introduced from Europe as an ornamental and for erosion control, it is highly aggressive and forms dense, monotypic stands which reduce wildlife habitat and hinder revegetation of upland sites and wetland buffers.
Legal status in King County, Washington
Public and private landowners are not generally required to control infestations of Scotch broom that occur on their property in King County, Washington, with the exception of the highway right-of-way of I-90 east of mile post 34 and on the right-of-way of Highway 2 where it dips down into King County before crossing Stevens Pass, in order to reduce its spread to neighboring Kittitas and Chelan Counties. Scotch broom is a Class B Noxious Weed in Washington, first listed in 1988. It has not been designated for required control in the county by the Washington State Noxious Weed Control Board, but it has been selected for required control in the limited area described above by the King County Noxious Weed Control Board. Because control is not generally required in the county, it is on the list of Non-Regulated Noxious Weeds in King County. For more information, see Noxious Weed Lists and Laws or visit the website of the Washington State Noxious Weed Control Board.
This species is also on the Washington quarantine list (known as the prohibited plants list) (external link) and it is prohibited to transport, buy, sell, offer for sale, or to distribute plants or plant parts, seeds in packets, blends or "wildflower mixes" of this species, into or within the state of Washington.
Biology and morphology
Scotch broom is loosely branched with green, slender ribbed branches and small, simple leaves up to half an inch long. It grows from 3 to 10 feet in height. The bright yellow flowers are pea-like, about three-quarters of an inch long. Its seed is borne in dark brown to black hairy, flattened pea-like pods, which when ripe, burst and scatter seeds for yards. Scotch broom grows primarily in open, dry meadows and along roadsides. It is often confused with Spanish broom, which looks similar but is easily distinguished by its rounded, bright green stems, fragrant blossoms, and later flowering time.
Additional information on scotch broom
What to do if you find this plant in King County, Washington
Because scotch broom is so widespread, property owners in King County are not required to control it and we are not generally tracking infestations. We can provide advice on how to control scotch broom, but there is generally no legal requirement to do so.
Scotch broom photos - click thumbnail for larger image