It looks harmless enough; that bold yellow-when-in-bloom shrub often seen along roadways does have a somewhat aesthetically pleasing look to it. At least from a distance.
Cytisus scoparius, commonly known as Scotch broom, is anything but harmless, and “aesthetically pleasing” is probably the last thing many would associate with the weed, which is native to the British Isles and a member of the pea family. In the Northwest, it blooms with abandon from April to June.
Scotch broom has an “invasive species” tag attached to it, a moniker that puts it in the same category as ivy, holly, blackberry, Daphne, knottweed and yellow arch angel. These types of weeds choke out the native plant species and are a threat to numerous environments. There is, however, an army of groups and individuals that have declared war on invasive species.
For two avid recreationists — Harold Mead and Maggie Sullivan — their battle against Scotch broom is personal and they have gone to extreme lengths to eradicate what Washington state lists as a Class B noxious weed.
Their battle includes countless hours removing Scotch broom in all sorts of conditions and terrain. Theyve donned climbing gear and rapelled down sheer walls in order to locate and remove the plant.
For Mead, it became personal when Scotch broom began to take hold of a chunk of rock near and dear to him: the crags of Mount Erie. To add insult to injury, lately he’d noticed the broom growing upon the bluffs of Cap Sante.
“I spent a lot of time on the south side of Mount Erie, climbing and whatnot,” Mead said. “I am really into native wild flowers and what I saw was that the broom was forming a culture all its own in the meadows. I realized then that if left on its own, it would annihilate the environment and completely eradicate all the native species.”
So Mead did what any weed-hating individual would do — he began pulling it up. From that first yank, Mead and his numerous disciples have been on a crusade.
“It was easy to pull it out because the soil was so thin,” he said. “What I found was a long tap root. What I also discovered was the bigger and older the plant, the more difficult it was to remove.”
That ease of removal, however, came at a price, as most of the soil came up along with the broom’s roots, leaving nothing but exposed rock. So the least obtrusive way of removal was to cut the broom’s stem below the soil line.
Where applicable, a single drop of an 8 percent solution of glyphosate is applied to the cut stem for the final coup de grâce.
“That is highly effective,” said Sullivan. “Stump treatment pretty much assured it won’t be coming back. Of course, the easiest way is to simply pull it out or cut it below the soil line.”
The removal of the invasive species is 100 percent successful when the entire root system is removed. This tends to be accomplished easiest during springtime rain when the ground is soft and before the plant goes to seed.
The plant, when left to its own devices, will grow in a single stock. However, if browsed by a herbivore or otherwise disturbed, the plant will branch out. If cut above the soil line, there is less than a 50 percent chance of eradication.
Scotch broom was introduced in the 1850s as an ornamental plant, and was later used for highway erosion control.
“Interstate 5 and Highway 20 are full of Scotch broom,” said Sullivan. “You can see it everywhere as you drive those corridors.”
It’s a highly aggressive, invasive species that has a number of negative impacts. It reduces wildlife habitat, hinders native plant growth in meadows and riparian boundaries, and delays the establishment of new trees in areas clear-cut.
“Broom thrives in clear cuts,” said Sullivan. “Once the trees are gone, up comes the broom. Once it takes root, then the trees won’t grow.”
The plant’s seeds can be viable for decades due to their hard, pod casing.
Adult plants produce seeds by the third and fourth years, and after eight years, the plant begins to degrade. Scotch broom has a lifespan of 10 to 15 years.
While completely eradicating Scotch broom and many other invasive species may not be feasible in the foreseeable future, control is certainly possible.
“What we want people to do is just pick an invasive species they want to attack,” said Sullivan. “Do some research. It’s important to be educated. Then pick a spot — making sure to ask the land owner if it is on private property — then go to work. Adopt that particular area and once you’ve cleared it out, then it’s just a matter of doing follow-ups.”
Both Mead and Sullivan perceive broom as a personal offense. They see attacking it as a way to give back.
“You’re outside, doing what you can to help the environment and native species of plants,” Sullivan said.
n Vince Richardson can be reached at 360-416-2181 or by email at email@example.com.