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Invasive Species |
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Tree Killers
Siberian Peashrub
(Caragana arborescens)
 Photo 26: Kitty Kohout, Wisconsin State Herbarium Biology
- a perennial, woody shrub that grows to four metres tall (12 ft)
- belongs to the Pea family
- four to six pairs of small leaflets make up each compound leaf
- pairs of sharp spines occur at the base of the leaves
- fragrant, bright-yellow flowers are produced in spring that develop later into long bean-shaped pods containing many seeds
- when mature, the pods turn brown and pop open, ejecting the seeds away from the parent shrub
- drought and salt tolerant and able to grow in poor, dry soil
- has a very dense and extensive root system
- can reproduce from seeds and from root suckers
 Photo 27: John M. Randall/The Nature Conservancy History in Canada
- commonly planted for hedges and windbreaks, especially on the prairies
- escaped from Alberta to Quebec but mainly a problem on the prairies
Impact on Trees
- may grow in dense stands in open woodland, forest openings, or woodland edges
- suppresses native tree seedlings due to shade
 Photo 28: Dave Powell, USDA Forest Service Control
- cutting trunks followed by herbicide application to the cut trunks
- herbicide application to the entire shrub
- several years of control may be needed since the seeds are unaffected by the above methods and seedlings can recolonize an area
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