YELLOWSTONE ARBORETUM
" Stewards of the Natural Environment "
Billings, Montana @ ZooMontana
Black Locust
Purple Robe
Catalogue A#2004-009 Z16
GPS 45D 43' 56" N / 108D 37' 15" W
2004-009
Robinia ambigua 'Idahoensis' 'Purple Robe', Robinia pseudoacacia
Family: Fabaceae (Leguminosae)
Origin: North America
Common Name: Purple Robe Locust
Location: Plaza-East side pathway just before brick walkway
Number in accession: 1
This specimen has survived whereas others planted in the past (in different areas) have not
This 13 inch Black locust provides overall benefits of: $109 every year.
Black locusts have invasive traits that enable them to spread aggressively. While these trees have demonstrated invasive traits, there is insufficient supporting research to declare them so pervasive that they cannot be recommended for any planting sites. Review of risks should be undertaken before selecting these trees for planting sites. Black locust produces hanging clusters of very fragrant white flowers in spring. This fast-growing native tree can form colonies and has brittle wood. Sharp spines may be present, especially on sucker growth. They are also susceptible to locust borers.
Tree or Plant Type: Tree
Foliage: Deciduous (seasonally loses leaves)
Native Locale: North America
Size Range: Large tree (more than 40 feet), Medium tree (25-40 feet)
Mature Height: 30-50 feet
Mature Width: 20-35 feet
Light Exposure: Full sun (6 hrs direct light daily), Partial sun/shade (4-6 hrs light daily)
Hardiness Zones: Zone 4, Zone 5 , Zone 6, Zone 7, Zone 8
Soil Preference: Moist, well-drained soil
Acid Soils: Tolerant
Alkaline Soils: Tolerant
Salt Spray: Tolerant
Soil Salt: Tolerant
Drought Conditions: Tolerant
Poor Drainage: Intolerant
Planting Considerations: Aggressive, Excessive sucker growth, Highly susceptible to ice damage, Messy fruit/plant parts, Weak wood and branch structure
Ornamental Interest: Spring blossoms, Fragrant flowers, Persistent fruit/seeds, Showy flowers, Attractive bark
Season of Interest: Late spring
Flower Color & Fragrance: Fragrant, White
Shape or Form: Oval, Thicket-forming
Growth Rate: Fast
Transplants Well: Yes
Wildlife: Insect pollinator