Bristly locust or Rose Acacia
(Robinia hispida)
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
- 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.
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.
- 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.