Cytisus scoparius
Midwest Noxious Weed: Do Not Plant
Common Name: Scotch broom 
Type: Deciduous shrub
Family: Fabaceae
Native Range: Europe
Zone: 5 to 8
Height: 4.00 to 8.00 feet
Spread: 4.00 to 8.00 feet
Bloom Time: May to June
Bloom Description: Yellow
Sun: Full sun
Water: Dry to medium
Maintenance: Medium
Suggested Use: Naturalize
Flower: Showy, Fragrant
Fruit: Showy
Tolerate: Drought
This plant is listed as a noxious weed in one or more Midwestern states outside Missouri and should not be moved or grown under conditions that would involve danger of dissemination.

Culture

Grow in moderately fertile, dry to medium, well-drained soils in full sun. Good drought tolerance. Grows best in full sun. Tolerates poor rocky soils (good bank cover). Avoid wet soils. Plants will spread invasively to form large stands. Invasiveness is primarily due to self-seeding. This species is marginally winter hardy to the St. Louis area.

Noteworthy Characteristics

Cytisus scoparius, commonly called common broom or Scotch broom, is a multi-stemmed, deciduous/evergreen shrub that grows 4-8' tall and features generally upright, broom-like, slender green branching and bright yellow flowers. Green-ribbed branches are sparsely clad (but are often leafless), with small, alfalfa-like, trifoliate leaves (with 1/2" long leaflets). Fragrant, sweet pea-shaped, bright yellow flowers (to 1" long) appear in late spring in an often showy bloom. Flowers are mostly solitary or in pairs. Fruit is a flattened, pea-like, green seed pod (to 2" long) with hairy margins. Pods mature to brown/black in fall and will snap open when ripe, explosively ejecting seeds several yards away. This shrub fixes nitrogen on root nodules. Common broom is native to central and southern Europe. It was introduced into the U.S. in the early 1800s as an ornamental shrub and for erosion control use. Over time, it has escaped gardens and naturalized in the East, far West and Hawaii. Plants have generally proved to be less aggressive in the East than in the West where they are listed in several states as invasive weeds.

Genus name comes from the Greek word kytisos used by the Greeks for several kinds of woody legumes.

Specific epithet means broom-like.

Problems

No serious insect or disease problems. In some environments, common broom can spread invasively to form dense stands that crowd out native plants. It is considered to be an invasive species in California and the Pacific Northwest (Class B noxious weed in Washington and Oregon). A mature broom shrub can produce up to 12,000 seeds per year which can remain viable in the soil for up to 20 years.

Garden Uses

Cultivars of this plant are much less aggressive (some do not produce seed). Where winter hardy, common broom makes an interesting addition to landscapes and garden areas. It can also provide good erosion control on slopes or hilly areas.