Photo courtesy of Brother Alfred Brousseau, St.Mary's College of California

 

Description: Scotch broom is a perennial shrub six to ten feet tall. Its sharply angled branches generally have fine green ridges with hairs on them when young; as the branches mature the hairs fall off, and the branches become tan and lose the distinct ridges. Pods have hairs along the seams only. One or two golden yellow pea-like flowers cluster between the leaf base and stem. 

 

Habitat: Scotch broom is common in disturbed places, such as river banks, road cuts, and forest clearcuts, but can rapidly colonize undisturbed grasslands, shrublands, and open canopy forest below 4,000 feet. It tolerates a wide range of soil moisture conditions and is competitive in low-fertility soils.

 

Distribution: Scotch broom is native to Europe and North Africa. Its natural range is broad, from Great Britain to the Ural Mountains and from Sweden to the Mediterranean. Introduced to California in the 1850's as an ornamental in the Sierra Nevada foothills, it was later used to prevent erosion and stabilize dunes. Scotch broom is now found along the California coast from Monterey north to the Oregon border.   Scotch broom is also prevalent in the interior mountains of northern Californian on lower slopes and very prevalent in the Sierra Nevada foothills. 

 

Flowering period: Blooms in late March to April inland, April to June on the coast. Long-lived seeds are copiously produced (to 12,000+ seeds/mature shrub) and mature in June and July. Seeds disperse from the pod with an audible pop, and are further dispersed by ants and rain wash on the ground. Seeds are known to survive at least five years in the soil and possibly as long as thirty years. The seed bank can build to over 2,000 seeds/square foot.

 
Eradication note: Manually pull these plants prior to seeding or flowering. For large infestations, a Weed Wrench™ is recommended. Do not allow these plants to seed as they have a persistent seed bank that will require subsequent treatments. Cutting the plant off at the base will not kill it as is readily resprouts. The entire plant with root system must be pulled.