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Woody > Robinia > Robinia pseudoacacia > Robinia pseudoacacia 'Purple Robe'

Robinia pseudoacacia

'Purple Robe'

Black Locust Tree

Origin:  Horticultural origin.
'Purple Robe'
Tree (deciduous)
USDA Hardiness Zone
4 - 8
Canadian Hardiness Zone
2a - 8a
RHS Hardiness Zone
H4 - H7
Temperature (°C)
-35 - (-9)
Temperature (°F)
-30 - 20
9 - 15 m
6 - 9 m
Description and Growing Information
Flowering Period
General Description
A fast-growing medium-sized tree with thin, weak branches. It has a fast spreading root system that will frequently pop up new shoots and can be beneficial in that regard for erosion control and soil fixation.
Improvement in soil-eroded environments due to its root formation. Only use in an urban setting for wind cover, accent or its pleasant fragrance if left to an open space due to its intricate root formation.
Can tolerate high saltine soils, drought, and poor soil (acidic or alkaline). It can grow in, but is not limited to, full sun and partial shade.
Upright compact oval position.
ID Characteristic
Identifiable by the seed pods, which are a leather type seed pod, and appear in a range from red to black. Channeled bark with spines on either side of lateral buds. Long,raceme-shaped purple flowers with a strong fragrance.
Caterpillars, weevils, scales, whiteflies, or the locust borer. Prone to cankers, leaf spots, powdery mildew, wood rot and verticillium wilt. Locust leaf miner is common but only browns the foliage on the tree.
Horticultural origin.
Bark/Stem Description
Exceptionally hard, strong and thorny bark. Brittle thorny branches.
Flower/Leaf Bud Description
Apical buds of this cultivar are missing while the other buds appear small and in clusters. They have 2 spines that appear on either side of the bud, framing it.
Leaf Description
Leaves appear in an alternate style. They are an entire, odd-pinnately compound leaf with pinnate venation. The individual leaflets are considered to be elliptical or oval shape that are less than 5cm long.
Flower Description
Impressive, fragrant pink-to-dark purple flowers that measure 10 - 20 cm across. The flowers bloom in May, lasting between 10 - 14 days.
Fruit Description
Dry leathery seed pods. They contain 4-8 seeds in each pod and can remain on the tree through winter. The pods themselves are measured between 5 - 10 cm and are a black-red colour.
Colour Description
Grey-brown trunk with darker grey-brown thorns. Branches are a slightly paler grey-brown. New branch growth appears as a red-gold colour which turns to grey-brown with age. Foliage colour varies through the seasons from purplish-red, to dark green at the beginning of the year, blue green into summer and yellow in autumn.
Texture Description
Coarsely textured bark that remains deeply furrowed through the seasons.
Notable Specimens
Laking Garden in Royal Botanical Gardens, Burlington, ON, Canada.
Propagation by seed and cuttings.
dward F. Gilman; D. G.Watson (November 1993). Robinia pseudoacacia ‘Purple Robe’: ‘Purple Robe’Black Locust. Florida: University of Florida. Retrieved from CSU/ Denver County. (2010, 05 01). colostate. Retrieved from Purple Robe Locust (Robinia pseudoacacia 'Purple Robe'):