IDAHO LOCUST
Robinia × ambigua 'Idahoensis'
FAMILY Fabaceae
SYNONYMS
ADDITIONAL COMMON NAMES
See: all Robinia
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by M. Ritter
GENERAL INFO
Flowers are a bright magenta rose color. This is one of the showiest locusts in bloom.
Native range: Eastern and Central United StatesHorticultural use: Screen
Native range: Eastern and Central United StatesHorticultural use: Screen
TREE CHARACTERISTICS
Tree Shape: RoundedFoliage Type: DeciduousMaximum Tree Height: 40 feetCanopy Width: 30 feetGrowth Rate: ~24-36 in/yearLeaf Arrangement and Leaf Form: Alternate, Pinnately CompoundLeaf Shape: OblongLeaf color: GreenFall Color: YesFlowers: ShowyFlower Color: Pink or Purple or RoseFlower Type: Has male and female reproductive parts in each flower (perfect)Flower Time: Spring or SummerFruit: Large Brown LegumeFruiting time: Fall or SummerBark Color: Light Green, FissuredLitter Type: Dry Fruit
SITE CONDITIONS
Recommended Planting Area: 4' to 7'Water Use Rating: MediumSunset Climate Zone: 2 - 24Shade Tolerance: NoUSDA Hardiness Zone: 4, 5, 6, 7, 8, 9, 10Soil Texture: Loam or Sand or ClaySoil pH: Very Acidic to Very AlkalineSalt Tolerance: Moderate
CONSIDERATIONS
Branch Strength: Medium WeakRoot Damage Potential: HighPotential health issues: No known hazardsWildlife interactions: Attracts birdsDisease and Pest susceptibility: Fusarium, Armillaria, Root Rot and AphidsUtility Friendly: NoWCISA Appraisal: Suggested LCANT 24" box, Group 2, Approx. cross sectional area 2.24 sq. in.
External Resources
CITE THIS TREE
"SelecTree. UFEI. "Robinia × ambigua 'Idahoensis' Tree Record." 1995-2025. Cal
Poly State University, San Luis Obispo. Accessed on May 22, 2025."
< https://selectree.calpoly.edu/tree-detail/1288 >
< https://selectree.calpoly.edu/tree-detail/1288 >
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