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Invasive Species of the Month: June 2012

Scotch broom (Cytisus scoparius)


Also Known As

English broom, broomtops, commom broom, European broom, Irish broom

General Description

Scotch broom is a long living perennial shrub that is native to western and central Europe. It can form dense, impenetrable stands that displace native species, degrade rangeland and wildlife habitat, and increase the risk of wildfires. Scotch broom reproduces by seed and can be toxic to humans and livestock when ingested.

Growth Habit

Dark green stems are 5–angled with smooth, sharply angled branches. The plant usually grows 3–9 feet tall, but can reach up to 13 feet. Scotch broom has an aggressive root system that consists of a deep, branched taproot and large, shallow lateral roots.

Leaves

Leaves are small, alternate, and comprised of 3 oval leaflets. The leaves may not be noticeable due to the plant's dark green stems, and are absent from late summer to early spring.

Flowers

Bright yellow flowers are approximately 1 inch long, sometimes with red or purple petals. Flowers have 5 petals, occur individually or paired in the leaf axils, and bloom from March through June.

Seeds and Fruit

Flat seedpods are 1–2 inches long and dark brown to black with fine white hairs along the edges. Seedpods burst when mature, scattering 5–9 bean-like seeds over several feet.

Habitat

Scotch broom can rapidly invade disturbed areas and thrives in dry, sandy soils with full sun. It can be found in both mountainous regions and cool coastal areas and is usually found in open forests, grasslands, pastures, meadows, dry riverbeds, and along roadsides.


Additional Resources

Species Identification and Characteristics
BugwoodWiki
Invasive.org Images and Overview
Montana State University Extension Fact Sheet (PDF)
Montana Weed Control Association Fact Sheet
The Nature Conservancy Canada Fact Sheet (PDF)
USDA Forest Service Fact Sheet (PDF)

Management and Control Resources

Biology, Ecology, and Management of Scotch Broom: Montana State University Extension (PDF)
Scotch Broom: Biology and Management in the Pacific Northwest: Oregon State University Extension (PDF)
USDA Forest Service Species Information

 

Past "Invasive Species of the Month" Profiles