French broom (Genista monspessulana) is a shrub native to the Mediterranean. It has naturalized in many areas throughout California, primarily on the coast. In Sequoia and Kings Canyon National Parks it is restricted to the Ash Mountain developed area. French broom is highly aggressive; its seeds are hardy, and are known to germinate vigorously long after the parent plants have been removed.

Identification

French broom can grow up to 3 meters (10 feet) tall. It has 3 small leaflets per leaf. The flowers are bright yellow and born in clusters. Each cluster has between 4 and 10 flowers. The bean-like pods are hairy and are generally between 15 and 25 millimeters (0.6-1 inches) long.

Look-Alikes

The only native species that may be confused with French broom in Sequoia and Kings Canyon National Parks is California broom (Lotus scoparius). California broom tends to have smaller leaves (6-15 millimeters or 0.2-0.6 inches long). The flowers of California broom are also smaller than the flowers of French broom.

Photo by Brother Alfred Brousseau, St. Mary's College

French broom produces numerous flowers and copious seeds.

Natural History

French broom reproduces entirely by seed. Each mature plant can produce hundreds of viable seeds each year. The seeds can remain viable in the soil for up to five years. Like many of the other non-native brooms in California, French broom has the ability to thrive in both disturbed and undisturbed areas at low elevations. Once established, these plants tend to exclude all others, and their seed banks can be extremely difficult to destroy.

Management

There are many populations of French broom throughout the developed area of Ash Mountain. Each year, thousands of new seedlings appear, concerned residents and employees of Ash Mountain remove many of these seedlings. It is likely that this volunteer effort has kept French broom at bay.

In 2002, Sequoia and Kings Canyon National Park Resource Management Personnel began working to eradicate French broom from the parks. Plants are being hand pulled. Annual surveys will be required to ensure that newly sprouted seedlings are removed as well. There are no known populations of French broom in Sequoia and Kings Canyon National Parks outside of the Ash Mountain area.