Scotch broom is a perennial shrub native to Europe. Along with other brooms, it is considered an invasive species by many communities, since it grows aggressively and it can quickly dominate the landscape. The plant is in a paradoxical position, as many invasive species are; some people think of Scotch broom as an obnoxious and irritable plant, while others deliberately cultivate it as an ornamental. Around the world, large amounts of money and energy are expended in attempts to eliminate Scotch broom.
The plant's formal name is Cytisus scoparius, and it is placed in the pea family. The shrub has leathery greenish branches and small leaves, with bright yellow flowers which appear in the late spring and summer. The flowers are replaced by brown seed pods, which will ultimately split with an explosive crack to eject the seeds. The seeds are small and copious, leading to serious problems for people who try to eradicate Scotch broom.
Scotch broom was carried to many communities around the world as an ornamental plant. Many cultivars are quite beautiful, with two toned yellow and red flowers or distinctive branching patterns. As Europeans traveled to new places, they may have brought the plant with them because it carried a familiar sense of home; this is how many invasive species reached delicate ecosystems. Once the plant is established, it can spread quickly, thanks to the small and rugged seeds.
Seeds are picked up by birds and other animals, or tracked on the bottom of feet. Scotch broom requires little to germinate beyond a small amount of moisture, and it can quickly overrun an area. The more plants appear, the more serious the problem is, as each plant will produce thousands of seeds in the late summer. Scotch broom tends to grow in very dense thickets, choking out native plants which cannot force their way through the thick branches. The timber industry particularly loathes Scotch broom, since the plant will take over in a clearcut area, preventing saplings from thriving.
The plant is a nitrogen fixer, which means that it can beneficial to the soil. However, the pernicious growth habit generally outweighs this benefit in the minds of most people. The only way to successfully eradicate Scotch broom is to pull it up before the seeds emerge, making sure to take up the entire root. The plants can be dried and then burned; burying or mulching is not recommended, since the roots may revive and start growing again.