Native Range

Europe

Appearance

Scotch broom is a shrub typically growing 3–10 ft (1–3 m) from a forked taproot. Stems are green, star-shaped in cross section, and hairy when young, but less hairy as the plant ages. Leaves are alternate, divided into three segments, and are deciduous. Flowers are usually yellow, up to 1 in (2½ cm) long, and are characteristic of the pea family by being two-parted with an upper and lower lip. Seed pods can grow up to 3 in (7½ cm) long; they are flattened and have hair on the margins, turning brown at maturity. This plant reproduces only by seed.

Impact

Scotch broom competes aggressively with other plants for nutrients, light, and water. It displaces native and/or more desirable species, reducing range, pasture, and commercial forest production. Older growth is unpalatable to grazing animals, and toxic compounds in seeds have resulted in livestock death. Although goats, sheep, and wildlife will browse young growth and flowers, the negative impacts outweigh the positive because dense stands of Scotch broom form impenetrable thickets that block access to water and more desirable forage. The high oil content of Scotch broom foliage and seeds and the large amount of dead growth beneath their canopies make Scotch broom an extreme fire hazard.

Reference

Andreas, J.E., M.J. Pitcairn, and P.D. Pratt. 2022. Scotch Broom (Cytisus scoparius): History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2022-7-SCOTCH BROOM-P. https://bugwoodcloud.org/resource/files/25361.pdf

Resources

• Element Stewardship Abstract - The Nature Conservancy

Selected Images

Maps

Invasive Listing Sources

• California Invasive Plant Council
• California Noxious Weeds
• Georgia Exotic Pest Plant Council - Category 4
• Hawaii Noxious Weeds
• Idaho Noxious Weeds
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Maryland Code and Regulations of Invasive Plants
• Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Massachusetts Invasive Plants Advisory Group List
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• Montana Noxious Weeds
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Native Plant Society of Oregon, 2008
• New Hampshire Invasive Plant Species Watch List
• New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture,  Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Reichard, Sarah. 1994.  Assessing the potential of invasiveness in woody plants introduced in North America. University of Washington Ph.D. dissertation.
• Utah Noxious Weeds - Prohibited
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States
• Wisconsin Noxious Weeds
• Wisconsin's Invasive species rule – NR 40

References