Laburnum alpinum
Common Name: Scotch laburnum
Type: Tree
Family: Fabaceae
Native Range: Southern and central Europe
Zone: 4 to 7
Height: 15.00 to 30.00 feet
Spread: 15.00 to 30.00 feet
Bloom Time: May
Bloom Description: Yellow
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Suggested Use: Hedge, Flowering Tree
Flower: Showy

Culture

Best grown in organically rich, medium moisture, well-drained soils in full sun to part shade. Best in full sun, but appreciates some part afternoon shade in hot summer climates such as the St. Louis area. Performs poorly in the heat and humidity of the deep South (south of USDA Zone 7). Best performance generally occurs in climates such as the Pacific Northwest where both summer and winter temperature are moderate. In St. Louis, it is best sited in a protected location to minimize risk of damage from sub-zero winter temperatures. If trained as a small tree, root suckers must be removed as they appear. Also consider removing the seedpods as they appear because they are not particularly ornamental, they consume plant energies and they are quite poisonous.

Noteworthy Characteristics

Laburnum alpinum, commonly called scotch laburnum, is a small deciduous tree or large shrub that is most noted for its pendulous axillary racemes of yellow, wisteria-like flowers that bloom in spring. It typically grows 15-25’ tall as a rounded tree and somewhat shorter as a shrub. Bright yellow, pea-shaped flowers in drooping racemes to 15” long bloom in mid-spring. Flowers give way to winged seed pods (2-3” long). Trifoliate, clover-like, glossy, medium to dark green leaves (to 3” long) produce little fall color. All parts of the tree are poisonous if ingested. Notwithstanding the common name, this species is not native to Scotland. It is native to the southern Alps, Czechoslovakia and Yugoslavia.

Genus name is the Latin name.

Specific epithet means alpine.

Problems

Twig blight is an infrequent but potentially serious disease. Canker and leaf spot are lesser disease problems. Watch for aphids and mealybugs.

Garden Uses

Small specimen tree or shrub for location around residential homes. Shrub borders. Group as a shrub to maximize effect of the spring bloom. Good background plant.