Other Common Names: weaver's broom
Weed class: A
Year Listed: 1998
Native to: Northern Africa, Western Asia and Europe
Is this Weed Toxic?:
not known to be
This plant is also on the Washington State quarantine list. It is prohibited to transport, buy, sell, offer for sale, or distribute plants or plant parts of quarantined species into or within the state of Washington or to sell, offer for sale, or distribute seed packets of seed, flower seed blends, or wildflower mixes of quarantined species into or within the state of Washington. Please see WAC 16-752 for more information on the quarantine list. For questions about the quarantine list, contact the Washington State Department of Agriculture's Plant Services Program at (360) 902-1874 or email PlantServices@agr.wa.gov.
Why Is It a Noxious Weed?
Like Scotch broom, its close relative, Spanish broom can dominate disturbed areas where it can out-compete native plants and alter soil nutrients. It does not provide good forage for wildlife and mature stands are noted to be a fire hazard in California.
How would I identify it?
Spanish broom is a perennial, evergreen shrub with round, green stems that are leafless for much of the year. It has bright yellow, irregularly shaped flowers. Shrubs can reach a height between 6 to 10 feet.
Flowers have an irregular shape, typical of flowers in the pea family (Fabaceae). They are bright yellow, about 1 inch long, and fragrant. Flowers grow in clusters at the end of stalks and the bloom time is typically between July and early frost.
Leaves are alternate and lance-shaped. They are less than 1 inch long, smooth on top and with long hairs on the leaf underside. Leaves only appear between February and early June.
Stems are bright green and round and are leafless most of the time.
Fruit Seed Description
Fruits are hairy seed pods, flat and linear, up to 3 inches long.
May Be Confused With
From a distance, Spanish broom looks very similar to Scotch broom (Cytisus scorparious), which is a Class B noxious weed in Washington. If you need help with identification, please contact your county noxious weed coordinator
Where does it grow?
Its high tolerance to drought and ability to produce nitrogen allow this shrub to grow in sunny, dry, areas with poor, often rocky soil. Like Scotch broom, it is typically found in disturbed areas including eroded slopes, vacant lots, and roadsides. Please click here to see a county level distribution map of Spanish broom in Washington.
How Does it Reproduce?
Spanish broom reproduces primarily by seed. One plant can produce between 7,000 to 10,000 seeds in just one growing season. Seeds can remain dormant for at least five years, although broom seeds have been shown to survive for over 25 years.
How Do I Control It?
General Control Strategy
Because Spanish broom produces so many seeds, it is important to watch for new seedlings, especially if the soil is disturbed. Fortunately, seeds do not appear to germinate when covered with 10 cm of soil, so heavy mulching may be an effective means to prevent new infestations.
Small plants and seedlings can be effectively controlled through hand hoeing. Hand-pulling can be effective when shrubs are still small and the entire root structure can be removed. Otherwise, the root fragments will re-sprout new plants. The best time to hand-pull is between July and September, especially when the soil is dry. The stems of large shrubs can be cut; however, re-sprouting will occur unless the cut stump is treated with herbicide.
Heavily mulching and then re-vegetating the infested area with native plants or non-invasive garden ornamentals can help prevent re-establishment of Spanish broom.
For More Information
See our postcard for early detection information about Spanish broom.
See our Written Findings for more information about Spanish broom (Spartium junceum).
King County NWCB Fact Sheet on Spanish broom
Control Options for Spanish broom from King County NWCB