Siberian peashrub

Shrub or multi-stemmed tree in the pea family, with individual yellow flowers.

Other names for this plant include:

• Common names: Siberian pea tree, pea tree
• Scientific names: Caragana arborescens var. pendula; Caragana fruticosa; Caragana arborscens var. redowskii; Caragana sibirica; Robinia altagana var. fruticosa; Robinia caragana

Classification in Wisconsin: Restricted (cultivars Lorbergii, Pendula, and Walkerii are exempt)

Ecological Threat

• Invades coniferous and hardwood forests, plantations, forest edges, savannas, trails, and right-of-ways.
• She is reportedly invasive throughout the Upper Midwest and Great Plains states.
• Extremely adaptable to a variety of soil conditions, salt and cold temperatures.
• It contains nitrogen-fixing microbial symbionts, altering natural soil chemistry and associated plant communities.
• Inhibits growth and establishment (allelopathic) of some grasses.
• Produces a chemical that reduces herbivore predation and pathogen establishment.

Identification

Leaves & stems: Shrub or multi-stemmed tree. Alternate, pinnately compound leaves with 8-12 leaflets. Young leaflets are silky in texture, while mature leaflets are hairless. Tips of leaflets contain a spine.

Flowers: Yellow, singular flowers characteristic of the pea family. Flowers are fragrant and borne on long stalks.

Fruits & seeds: Seeds are in 1-2 inch pods, smooth and brown with sharply pointed tips. Pods eject seeds when they mature.

Roots: Nitrogen-fixing symbionts form nodules on the roots.

Control

Mechanical:

• Dig up individual plants. For larger populations, mow as close to the ground as possible. Continual mowing is needed as plants rapidly re-sprout.
• When leaves emerge, cover the infestation with black landscape fabric/plastic in early spring. Keep covered for a minimum of one growing season.
• Consecutive prescribed burns may be a successful control option, with sufficient fuel loads and fire-appropriate habitats.

Chemical:

• Cut-stump treatment with glyphosate.
• Cut-stump or basal bark treatments in fall with triclopyr.

Resources

Sources for content:

• Shortt, Katelyn B., Vamosi, Steven M. 2012. A review of the biology of the weedy Siberian pea shrub, Caragana arborescens, with an emphasis on its potential effects in North America. Botanical Studies, 53:1-8.
• Minnesota Department of Natural Resources
• National Park Service

Links for more information:

• USDA PLANTS Profile [exit DNR]
• Wisconsin State Herbarium [exit DNR]