Scotch Broom sweeping the county

By Janet Carroll, Mukilteo Wildlife Habitat Project | Mar 23, 2011

Scotch Broom (Cytisus scoparius) is a shrub in the pea family that was used in its native Europe as a broom.

However, the plant did not come to the United States to be used for sweeping; it was brought here because of its beautiful bright yellow flowers and ultimately came to be the choice for stabilizing slopes, especially along roads.

 Dense stands of shrubs with eye-catching yellow flowers are commonly seen along highways – that’s Scotch Broom. Maybe you even sneezed a few times if you are allergic to the pollen produced by the masses of yellow flowers.

Scotch Broom has spread into Mukilteo’s gullies and elsewhere.  

Walk the sidewalk along the Speedway adjacent to 92nd Street Park, and you will find a couple of examples in Big Gulch.

This plant forms pure, dense stands that eliminate more desirable plants.  Because it is a threat to native plants and indirectly to animals that feed on the displaced plants, Scotch Broom is listed as a Class B noxious weed in Washington State. This classification is intended to “contain the plants where they are already widespread and prevent their spread into new areas.”

I believe the message is – don’t let any more grow.

This invasive plant has one characteristic that makes it extremely hard to eradicate; its prodigious seed production. One plant can produce as many as 18,000 seeds.

The seed pods explode when they are mature scattering seeds to the wind. The thick, hard coat allows it to stay viable for up to 60 years or more.  

I see Scotch Broom most often in disturbed areas, like a newly cleared site left unused over a few seasons, and of course along roads.  

Seeds stick to tires, heavy equipment, shoes, and infest gravel.

The seeds are also moved by runoff into streams and gullies, eventually sprouting along streambanks and gully walls.

Birds and ants eat the seeds and are partly responsible for dispersal, but birds don’t seem to be the major seed-spreading culprit this time.

If you see a small Scotch Broom plant, pull it out – it’s easy.  

It’s a different story when they are big; they can grow to be 6-10 feet tall.  

There is a tool called a weed wrench that works well for this plant and any other woody plant that you can get the jaws around.  The jaws are placed around the bottom of the stem and you can either pull on the plant or use the leverage of your weight against the tool to force the roots out.  

Using this tool on Scotch Broom made removal much easier for me than trying to get it out any other way.  

Information on the weed wrench can be obtained from the following Web site:   http://www.weedwrench.com/weedwrench/.

In checking the status of Scotch Broom, I found that it is not listed as a noxious weed in Snohomish County, but a member of its family, Gorse (Ulex europaeus), is on the Class B Undesignated list.  That means that it is not designated in the state, but is in the county and must be controlled by the landowner.

Gorse can be distinguished from Scotch Broom by its spiky leaves that grow outward leaving a dense inner area of dead plant material.  This makes it susceptible to fire since the oil in the plant is highly flammable.

In Mukilteo, one plant at least is marked with red flagging, so I assume at some point the plant will be removed, but it has been there for some time, which means that there are probably thousands of its progeny in the ground or elsewhere waiting to sprout.  


Janet Carroll is a member of the Mukilteo Wildlife Habitat Project, which has a goal of certifying Mukilteo as a community wildlife habitat.  Help Mukilteo get community certification by certifying your own yard.  For more information on the project, go to www.mukilteowildlife.org.

Do you have questions about how to get rid of noxious weeds?  E-mail Carroll at mukilteowildlife@gmail.com.



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