French broom identification and control
Genista monspessulana, Fabaceae Family
Legal status in King County, Washington
Public and private landowners are required by state law to eradicate this plant when it occurs on their property. French broom is a Class A Noxious Weed in Washington due to its limited distribution in the state and the potential for significant impact to state resources. It was added to the state list in 2013. It is on the King County list of Regulated Class A Noxious Weeds. For more information see Noxious Weed Lists and Laws.
- Large tap-rooted shrub with yellow, pea-type flowers and small oval leaves in groups of three
- Older stems are brown and more or less round; younger stems are green, ridged and very leafy
- Leaves and young stems covered with silvery hairs
- Flowers are small and in clusters of 4-10 on ends of small branchlets
- Seeds are in small brown pods, 0.4 to 1.2 inches (1-3 cm) long, covered with silky, silvery to reddish gold hairs
- Can be distinguished from Scotch broom by its brown stems, leaves always in threes (some Scotch broom leaves are single), smaller flowers, and seed pods entirely covered by hairs (Scotch broom pods are only hairy on the edges)
Habitat and impact
French broom is a woody, tap-rooted shrub that reproduces by seed. It doesn't spread vegetatively from its roots, but plants can survive cutting and tend to re-sprout from the crown when cut or burned. Seeds are produced in hard, dry legume pods that burst open when mature. Seeds are generally dispersed close to the parent plant unless soil is moved through erosion, flooding or other means. Similar to other broom species, French broom seeds are hard and long-lived. Plants can produce over 8000 seeds a year.
Small patches: Plants can be hand-pulled when young or mechanically pulled with a weed wrench or similar tool when larger. Look for seedlings wherever plants have gone to seed in past years.
Larger patches: This plant can generally be controlled with the same methods as for Scotch broom. If applying herbicide, the best timing is when plants are most actively growing in the spring or early summer, before the dry season. On the other hand, cutting plants is most effective during the dry season, usually from late July to mid-September in this area. Please refer to herbicide labels for site specific control information and refer to the PNW Weed Management Handbook for additional information on herbicide use.
Additional information on French broom
- Washington State Noxious Weed Control Board (external link)
- Oregon Department of Agriculture Noxious Weed Program French Broom Info Page (external link)
- California Invasive Plant Council Genista Monspessulana Information (external link)
- Photos and Distribution from the University of Washington Burke Museum (external link)
- Genista monspessulana images from CalPhotos (external link)
What to do if you find this plant in King County, Washington
Please notify us if you see French broom growing in King County. Our program staff can provide the property owner or appropriate public agency with site-specific advice on how best to remove it. Also, because French broom is not generally established in King County, we have an opportunity to stop it from spreading if we act quickly. We map all known locations of regulated noxious weeds such as flowering-rush in order to help us and others locate new infestations in time to control them.
Report French broom in King County, Washington
- Please notify us through our online infestation form
Locate French broom in King County, Washington
- Use our interactive noxious weed map and search for French broom