Scotch Broom

Cytisus scoparius

Family: Fabaceae

Other common names: broomtops, common broom, European broom, Irish broomScottish broom

Weed Class: B

Year Listed: 1988

Native to: Europe

Toxic: livestock

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Why is it a noxious weed?

It displaces native and beneficial plants, causing loss of grassland and open forest. It aggressively spreads to form monocultures, replacing desirable forage grasses and young trees. Seeds are toxic to livestock and horses.

How would I identify it?

General Description: Scotch broom is a perennial, many-branched, shrub ranging in height from 3 to 10 feet tall.

Flower Description: Flowers are typical of those in the pea family. They are bright yellow, about 3/4 inches long and have 5 petals.

Leaf Description: There are few leaves. The upper are simple and the lower are 3 parted. They are deciduous and pointed at both ends.

Stem Description: Stems are woody and dark green. Young branches have 5 green ridges with hairs. When mature, stems become glabrous and ridges disappear. Young stems remain green throughout the year.

Fruit/Seed Description: Seed pods are brown-black, legume-like, flattened and have hairy margins with several seeds per pod.

May be confused with: From a distance Spanish broom (Spartium junceum), a Class A noxious weed in Washington, and gorse (Ulex europaeus), a Class B noxious weed in Washington, look similar to Scotch broom. If you need help with plant identification, please contact your county noxious weed coordinator.

How does it reproduce?

Scotch broom reproduces by seed. Each seed can remain viable for up to 80 years.

Where does it grow?

Scotch broom can be found on roadsides, pastures, grasslands, open areas and areas of recent soil disturbance. Please click here to see a distribution map of Scotch broom in Washington.

How do I control it?

General Control Strategy

Because of lengthy time of seed viability, as well as large seed production, methods must be repeated for many years.

Mechanical Control

Hand pulling and digging may be an option for small infestations. Chopping, cutting or mowing is an option for flat areas. Cutting is recommended before herbicide application.

Biological Control

The Scotch broom seed weevil, Exapion fuscirostre, larvae feed on seeds of Scotch broom in developing seed pods. The adults also feed on flowers and the tips of stems, though their damage is not significant. The Scotch broom bruchid, Bruchidius villosus, larvae feed on developing seeds and impact the plant's reproduction. For more information about the biological control of Scotch broom, please visit WSU Extension Integrated Weed Control Project.