Biology and Biological Control of Common Gorse and Scotch Broom

“Common gorse (Ulex europaeus L., Figure 1-1a) and Scotch broom (Cytisus scoparius [L.] Link, Figure 1-1b) are related woody shrubs native to Europe. Both species were introduced to North America in the 1800s as ornamentals and later widely used in erosion control and as natural livestock fences. Both species escaped cultivation and are now invasive throughout western and eastern North America. Common gorse (hereafter referred to simply as gorse, its most common name) and Scotch broom continue to be available for purchase in the United States, though the sale of these two species is now illegal in states where they are classified as regulated plants or noxious weeds.

Although several exotic broom species have been intentionally or accidentally introduced to North America, Scotch broom is by far the most common and problematic for land managers. Gorse and Scotch broom have been the primary targets of biological control efforts in the United States, and are the focus of this manual. Additional information for understanding and differentiating other related broom species is given in Chapter 2.”