Photo by Jennifer Andreas.Īs you may have noticed, Scotch broom can be found throughout most of Washington, especially west of the Cascades. Scotch broom flower on a leafy stem, waiting for a pollinator to stop by. However, historical records do show us that Scotch broom was introduced from Europe numerous times over many decades, beginning before 1900 and continuing to the present (people continue to plant varieties of this weedy species in spite of a state quarantine against selling it in Washington, and sometimes they even transplant it for the pretty flowers). Invasive plants can become so entrenched and widespread that it is hard to tell them apart from native species (just look at Himalayan blackberry). Photo by Sasha Shaw.įinally, for those who believe this plant to be native to Washington, they are sadly mistaken. Scotch broom covering a hillside along a highway is a familiar sight in King County, but WSDOT doesn’t plant it. Unfortunately, broom seeds are so tough and so long-lived, that it is almost inevitable that this plant shows up whenever land is cleared, especially in highway rights-of-way where conditions are ideal for Scotch broom to prosper. When you see a newly constructed off-ramp or cleared highway shoulder suddenly sprout a field thick with Scotch broom, this is the legacy of the decades of Scotch broom seeding in the area, and not because of a misguided landscape plan. Secondly, although the state and other agencies did perhaps use Scotch broom in the past for roadside plantings (there is some discrepancy when I ask transportation officials this question), they are for sure no longer planting this species of broom along Washington highways. A open Scotch broom flower means it’s probably already been visited by a pollinator since the blooms usually don’t open by themselves. So, by all means blame the Scotch broom, but you might also have other allergies to deal with. However, the odor is thought to trigger headaches and other miseries in people with other allergies such as to grass. Allow me to respond to each of these half-truth, half-myths.įirst, the pollen of Scotch broom is very heavy and not very likely to be blowing in the wind. And third, I hear from newcomers to the area that they think it is a native plant because of how widespread it is. Second, people tell me that the highway department plants it everywhere. First, people tell me they hate this plant because they are allergic to it. There are three things I often hear about Scotch broom (or Scot’s broom, which may be the correct common name, but is not as commonly used). Scotch broom ( Cytisus scoparius) in flower is a cheery yellow but that just doesn’t make up for how invasive it is in Washington.