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Bristly locust or Rose Acacia

(Robinia hispida)

Photo of Bristly locust
Photo credit: Wisconsin DNR

Perennial shrub in the pea family with rose-colored flowers and red bristly stalks.

Overview

Other names for this plant include:
  • Common names: Rose acacia, mossy locust
  • Scientific names: R. hispida var. fertilis, R. hispida var. hispida, Robinia grandiflora
Ecological threat:
  • Invades numerous habitat types: upland forests, forest edges, prairies, forested dunes, grasslands, roadsides, disturbed vacant areas.
  • Previously planted as fence rows, escaping cultivation.
  • Tolerant of many soils, but most readily colonizes light-textured soils with good drainage, preferring sandy and silt loams.
  • Nitrogen-fixing microbial symbionts alter soil chemistry.
  • Expands creating dense thickets.
  • Seeds remain viable in the soil for 1-10 years.
  • Multiple sterile and nonsterile varieties exist, with both varieties naturalizing.
Overview map of bristly locust classification in WI
Restricted (orange) counties

Classification in Wisconsin: Restricted

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for bristly locust was based upon this literature review [PDF] developed by the department.

Identification

Leaves & stems: Alternate, pinnately compound leaves. Small round leaflets are bright green and paler on the underside. Stems covered in thick red bristles. The bark is grey-brown covered in raised lenticels.

Flowers, fruits & seeds: Rose-colored pea flowers. Seed pods are brown and flat, covered in dense reddish bristles.

Roots: Spreads by root suckering.

Control

Mechanical:
  • Pull small plants, use weed wrench on larger shrubs.
  • Remove all roots if possible and monitor for resprouts.
Chemical:
  • Use cut stump or basal bark herbicide techniques in fall with glyphosate or triclopyr.
  • Monitor for resprouts.

Photos

View bristly locust pictures in our photo gallery!

Resources

Sources for content:
  • University of Wisconsin - Stevens Point; Robert W. Freckmann Herbarium.
  • Virginia Tech Department of Forest Resources and Environmental Conservation.
Links for more information: