Locust, Idaho Flowering
Robinia x ambigua
Fabaceae - Legume
Description
Leaves: Presumably similar to the leaves of black locust: dark green in summer, yellow-green fall color, hairless; alternate; pinnately compound, 8" to 14" long; 7 to 19 elliptical and ovate-oblong or ovate leaflets, 1-1/2" to 2" long, entire margins; deciduous.
Twigs/buds: Similar to black locust: twigs moderately stout; often zigzag; generally have short, stiff spines, 1/4" to 1/2" long, in pairs at bases of leaves. No terminal bud; lateral buds hidden under cracks of bark near leaf scar.
Flowers/fruit: Flowers perfect; rose-pink; occur in late spring (May to June); fragrant; 1" long, but part of longer (6" to 8" in length), hanging racemes. Fruit similar to black locust; dark brown, flat legume; 3" to 5" long; containing 4-8 flat brown seeds.
Bark: Red-brown to nearly black; deeply furrowed into cris-crossing scaly ridges; inner bark may be poisonous.
Wood: Unimportant; presumably similar to that of black locust.
General: Probably a hybrid of black locust (R. pseudoacacia) and bristly locust (R. hispida) or R. viscosa. Often reaches heights of around 25' to 40' and a spread of 15' to 30', with a medium growth rate. Tough and tolerant of difficult conditions, including heat, dryness, and cold. Will get borers like other Robinias.
Landscape Use: Popular in the semiarid West, it differs from R. pseudoacacia in having beautiful pink flowers and a more open growth habit. Zones 3-8.
Cultivar: 'Idaho'.
Characteristics
General
Family | Fabaceae - Legume |
---|---|
Cultivar Availability | Yes |
Hardiness Zone | 3-8 |
Type | Broadleaf |
Utah Native | No |
Growth
Growth Rate | Medium |
---|---|
Mature Height | Medium |
Longevity | Medium |
Is Good Under Power Lines | No |
Crown Shapes | Oval |
Ornamental
Bark | No |
---|---|
Fall Color | No |
Flowers | Yes |
Foliage | Yes |
Fruit | No |
Tolerance
Shade | Low |
---|---|
Salt | High |
Drought | High |
Poor Drainage | Medium |
Alkalinity | High |
Transplanting | High |