Many plants sharing our gardens are not natives but imports from other lands. At the time, introducing the species probably seemed like a good idea, that is until it turns invasive and deadly.
Scotch Broom is a perennial shrub with lovely yellow pea-like flowers, dark green stems, and evil on its mind. OK I made up the evil part, but the more you know about Scotch Broom the more you might agree.
Scotch Broom was introduced in the US in the early 1800s.
History indicates that broom was imported as domestic sheep fodder. But, broom may have been imported for its wide variety of medical and utility functions.
Medical ailments treated included (Note: This weed is poisonous. Modern medicines provide safer alternatives):
|Jaundice||Kidney stones||Respiratory conditions||Snake Bite|
Utility functions included hair rinse, leather tanning, sweeping brooms, thatched roofs, rope, beer flavoring, yellow dye, and a substitute for hops, capers, and coffee. In addition, Scotch Broom roots host nitrogen-fixing bacteria which help the plant colonize nutrient-poor soils.
It is native to much of Europe and Africa where natural predators for the plant evolved.
In the early 1900’s, broom was planted to prevent soil erosion along Pacific Coast highways. It probably seemed like a great idea at the time.
It didn’t take very long for Scotch broom to become an international superstar pest. Today, broom is considered a pest throughout most of its range.
More than just one
Does it seem like the Scotch broom blooms more than once a year? Well, it does, kinda. There is more than one type of broom and more than one type lives on the Oregon Coast.
The ranges for Scotch, Spanish, French, and Portuguese broom overlap. You may notice different bloom seasons, lighter color flowers, height differences, and more. All have a nice yellowish bloom similar to a pea.
Scotch broom and Gorse are sometimes confused (Gorse is very stickery). They both grows in similar conditions, and cause similar problems, but are different species.
This plant has earned its weed status well by aggressively invading many areas. Once in place it is very difficult to get rid of and control. What makes it so bad?
Broom regenerates quickly, forming dense stands. These stands are unpalatable and somewhat poisonous to wildlife. They will become so dense that even quail cannot live there.
These thick dense stands will also prevent normal reforestation and regeneration processes and drive many native species out by shading, increasing soil acidity, and toxicity.
Broom increases fire hazard frequency and intensity. It is one of the most flammable plants there is and poses enormous threat to communities.
It creates a high fire hazard frequency and intensity. Even green, the shrubs will cause a fire to erupt. The broom is one of the most flammable plants there is and poses an enormous threat to our community’s fire safety.
The plant is a prolific seeder and can release 20,000 or more seeds per plant every year. Seeds stock pile over time until destroyed or germinated. Seed remain viable in the soil for decades and any disturbance can cause the seed to germinate.
Seeds will germinate after a ‘cooler’ fire (depending on the temperature of the fire). Hot fires can destroy the seeds.
It is hard to get rid of….
The only way to control this plant is through repetitive and ongoing treatments. Treatments include manual removal, chemicals, burning (hot), shading through planting, and some biological options (Bruhidius villosus, exapion fascirostre, and Leucoptera spartifoliella).
Once established, the plant is very drought tolerant. This tolerance makes herbicides less effective during certain times of the year.
Scotch Broom causes substantial timber revenue losses and costs a lot to control – somewhere over $40 million a year in Oregon alone.
–OSU Extension Service (https://extension.oregonstate.edu/news/scotch-broom-beautiful-noxious)
–King County, Scotch Broom (https://bit.ly/2X7XvAh)
–Scotch Broom (https://www.invasivespeciesinfo.gov/profile/scotch-broom)
–The News Review, Ask a Master Gardener… (https://bit.ly/2X9v4Sq)
–USDA Fire Effects Information System (FEIS) (https://bit.ly/3gar3ol)
–Wikipedia, Cytisus scoparius (https://en.wikipedia.org/wiki/Cytisus_scoparius)
–Weeds, Working Lands (https://bit.ly/30TRtUO)