TREES & plants

Bristly locust

Flowers and leaves of bristly locust.

Bristly locust is an upright, suckering shrub used to stabilize slopes. The purplish-pink pendulous flowers, blue-green foliage, bristle seed pods add seasonal interest. May be difficult to find in nurseries.

Botanical name: 
Robinia hispida
All Common Names: 
bristly locust; rose acacia; roseacacia locust
Family (English): 
Family (Botanic): 
Tree or Plant Type: 
  • Shrub
  • Deciduous (seasonally loses leaves)
Native Locale: 
  • Non-native
Landscape Uses: 
  • Hedge, 
  • Massing, 
  • Screen, 
  • Windbreak
Size Range: 
  • Large shrub (more than 8 feet)
Mature Height: 
6 to 10 feet high
Mature Width: 
10 to 15 feet wide
Light Exposure: 
  • Full sun (6 hrs direct light daily), 
  • Partial sun/shade (4-6 hrs light daily)
Hardiness Zones: 
  • Zone 5 (Chicago), 
  • Zone 6, 
  • Zone 7, 
  • Zone 8
Soil Preference: 
  • Alkaline soil, 
  • Dry soil, 
  • Moist, well-drained soil, 
  • Sandy soil
Acid Soils: 
  • Tolerant
Alkaline Soils: 
  • Tolerant
Salt Spray: 
  • Tolerant
Soil Salt: 
  • Tolerant
Drought Conditions: 
  • Tolerant
Poor Drainage: 
  • Intolerant
Planting Considerations: 
  • Dangerous thorns, 
  • Excessive sucker growth, 
  • May be difficult to find in nurseries
Ornamental Interest: 
  • Spring blossoms, 
  • Persistent fruit/seeds, 
  • Showy flowers, 
  • Attractive bark
Season of Interest: 
  • Late spring, 
  • Early summer, 
  • Mid summer, 
  • Late summer
Flower Color & Fragrance: 
  • Purple
Shape or Form: 
  • Irregular, 
  • Multi-stemmed, 
  • Round, 
  • Thicket-forming, 
  • Upright
Growth Rate: 
  • Fast
More Information: 

Tree & Plant Care

A large, suckering shrub up to  8 feet high with a spreading fan-shaped crown. Spreads by suckers creating thickets.
Best planted in full to part sun in all soils, including those that contain clay or sand. 
Prune regularly to keep in bounds.
Bristly locust has appeared on some invasive lists.

Disease, pests, and problems

Stem canker, mildew, leaf spots, leaf miner, scale, and borer

Disease, pest, and problem resistance

Tolerant of salt spray

Native geographic location and habitat

Native to North America

Attracts birds, pollinators, or wildlife

The nectar of the flowers attracts honeybees, bumblebees, and other long-tongued bees; occasional butterflies (which are poor pollinators), and possibly the Ruby-throated Hummingbird.

Bark color and texture 

The bark of the trunk and larger branches is gray and fairly smooth. Young branches are zigzag, green with very bristly-hairs. These long bristly hairs are purple-brown and sticky.

Leaf or needle arrangement, size, shape, and texture

Alternate, pinnately compound with elliptical 7 to 15 leaflets. The green stalk (rachis) is sticky, hairy and has a pair of sharp spines at the base. Upper leaves are medium green while their lower surfaces are pale green.

Flower arrangement, shape, and size

Attractive, rose-colored, pea-like flowers in hanging clusters are located in leaf axis and at the end of branches. Bloom period is late spring to mid-summer.

Fruit, cone, nut, and seed descriptions

Fertile flowers are replaced by flat pod, 2 to 3 inches long and very bristly.  Not very prolific.

Robinia hispida or Bristly locust