History and Impact
A perennial, evergreen shrub, Spanish broom is often mistaken for Scotch broom (Scot's broom) but can be distinguished by the fragrant flowers and rounded, bright green stems. It is a noxious weed because of its prolific seed production and aggressive replacement of native plants. As a Class A noxious weed, its eradication is required in King County.

Biology and Morphology
Spanish broom can grow 6 to 10 feet tall, in poor, rocky soil, and is common in disturbed areas such as roadsides, trails, state parks and vacant lots. The mainly leafless stems branch off at the top, ending with flowering clusters on leafless racemes (stalks). The leaves are simple and one-parted (as compared to the three-parted leaves of Scotch broom) and are alternate and less than 1 inch long. The leaf shape is linear to lanceolate, and hairs are present on the lower surface. Fragrant, bright yellow and pea-shaped, approximately 1 inch long, the flowers grow in clusters at the branch ends on stalks that can be 18 inches long. They can bloom from July to frost. The fruits are hairy seed pods, flat and linear, up to 3 inches long. Spanish broom spreads by seed.

For information on Spanish broom identification and control, please download our Spanish broom weed alert (166 KB Acrobat file).

For in-depth information on history, impacts, biology and control of Spanish broom in King County, please read the Spanish Broom Best Management Practices (420 KB Acrobat file).

For additional information about Spanish broom, please follow this link to the WA State Noxious Weed Control Board.

If you find Spanish broom in King County, please notify us through our online infestation form.

To find out where we have records of this weed in King County, use our interactive noxious weed map and search for Spanish broom.