Description and Variation:   Spanish broom is a perennial, evergreen shrub that can reach six to ten feet tall. The erect, bright green stems are rounded (rush-like) and mainly leafless. The stems branch off at the top, ending with flowering clusters on leafless racemes. The leaves are simple and one-parted, (as compared to the three-parted leaves of Scotch broom); they are alternate, short-lived, and less than one inch long. The leaf shape is linear to lanceolate. Hairs are present on the lower surface. The leaves are the same bright green color as the stems. The flowers are fragrant, bright yellow, and pea-shaped, approximately one inch long. The flowers grow in clusters at the branch ends, on stalks that can be 18 inches long. The flowers bloom from July to frost. The fruits are hairy seed pods, flat and linear, up to three inches long. Spanish broom spreads by seed. Spartium junceum is the only species of this genus. Distinguishing characteristics include the round stems, the simple one-parted leaves, and the fragrant flowers.

Economic Importance:

Detrimental: Spanish broom is a close relative of Scotch broom (Cytisus scoparius), a serious weed problem in western Washington. This species is capable of crowding out desirable native plants. Spanish broom is considered a potential fire hazard in California, when mature plants form dense, woody undergrowth in hard to reach, hilly areas. All parts of the plant are poisonous if eaten.

Beneficial: Spanish broom has been introduced as a garden plant or ornamental plant. It is also used as a bank cover in areas with poor, rocky soil. The flowers yield a yellow dye. The plant is used for fiber and for weaving and cordage in southern France and Spain.

Habitat:  Spanish broom is the most drought resistant of the broom species. It establishes in areas with full sun and limited water and it can grow in poor, rocky soils. This species is common in disturbed areas, roadsides, trails, state parks, and vacant lots in California.

Geographic Distribution:  Native of the Mediterranean region and Canary Islands. Spanish broom was introduced as an ornamental for sale in a San Francisco nursery in 1858 - it has since naturalized in California. Distribution of Spanish broom is not well known, partially because of the resemblance to Scotch broom. In Oregon, all Spanish broom infestations are subject to control.

History Washington sites include roadsides along freeway interchanges in Kelso; the Montlake Cut area in King County; outside of Lacey in Thurston County; in Clallam County; and on the roadside of US 101 in Hoodsport, Mason County.

Growth and Development Spanish broom is an evergreen perennial. It establishes in disturbed areas. Improper fire management may contribute to reinvasion.

Reproduction Spanish broom spreads by seeds or stump sprouting. The seeds germinate without any pretreatment. More information needed on seed production, dispersal, viability, germination, and seedling establishment. (Hoshovsky 1986).

Response to Herbicides It is recommended to apply herbicides when the plant is in full leaf, with the best results occurring when sprayed in late summer and early autumn (Matthews 1960 as cited in Hoshovsky 1986). 2,4-D is an herbicide commonly mentioned in broom control. Broom is susceptible to picloram (Allo 1960, Elliot 1976, Watt and Tustin 1976, Balneaves 1981 as cited in Hoshovsky 1986).

Response to Cultural MethodsBroom seeds buried more than 10 cm deep do not germinate. Future site disturbance will lead to germination and seedlings. (Hoshovsky 1986).

Response to Mechanical Methods Hand pulling is effective for the control of Spanish broom. The whole root must be removed because the fragments will resprout. Mowing will encourage resprouting from the root crowns. However, mowing is effective in controlling Spanish broom if it is followed by herbicide application.

Biocontrol Potentials  There are conflicting reports of control of Spanish broom by goat grazing. Chickens will reduce the seed bank; seeds are digested and will not germinate. A broom aphid (Aphis cytisorum) and Eriophyes spartii both feed on Spanish broom (Hoshovsky 1986).

Rationale for Listing:  Spanish broom is a close relative of Scotch broom (Cytisus scoparius), a serious weed problem in Western Washington. The aggressive replacement of native plants and habitats, prolific seed production, and lack of any natural controls are characteristics of Spanish broom. This species has naturalized in many areas of the west. The limited populations and distribution of Spanish broom in Washington state meet the requirements for a Class A Noxious Weed.

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