Purple Robe Locust

Robinia x ambigua 'Purple Robe'

Robinia x ambigua (Purple Rob Locust) - full view

Full view

Robinia x ambigua (Purple Rob Locust) - leaves

Foliage detail

Robinia x ambigua (Purple Rob Locust) - bark

Bark detail

  • Size:

    Height: 40'; Spread 30'

  • Growth:

    Fast

  • Character:

    Deciduous; upright, open canopy with arching branching habit.

  • Foliage:

    12-18" pinnately compound with 17-21 paired oval leaflets. Dark green.

  • Flower:

    8" long hanging clusters of fragrant, pink to dark purple 1/2-3/4" flowers.

  • Fruit:

    1.5-2.25" long, narrow, dark brown seed pods.

  • Bark:

    Gray to red-brown with scaly ridges and cracks.

  • Watering:

    In general, 15-20 gallons per week for the first 2 years; 15-20 gallons twice a month for the 3rd year; as needed after 3 years (varies by soil, sun, and wind conditions).

  • Tree Care:

    Moderate. Early pruning needed to train a good shape; pruning needed less frequently with age.

  • Tolerance:

    Drought (once established), any soil, some shade, and medium winds.

  • Special Considerations:

    Overwatering after 3rd year may cause rangy growth. Too much pruning promotes unnatural branching structure. Older trees may experience branch breakage.

  • Notable Traits:

    Hybrid of Robinia ambigua 'Decaisneana' and R. hispida 'Monument'. Known for beautiful flowers and winter silhouette.