Buckthorn leafs out early and retains leaves late into the fall, creating dense shade that helps it to out-compete many native plants.
Common buckthorn (Rhamnus cathartica) was first brought to Minnesota from Europe in the mid-1800s as a very popular hedging material. Shortly after its introduction here, it was found to be quite invasive in natural areas. The nursery industry stopped selling it in the 1930s, but many buckthorn hedges may still be found in older neighborhoods throughout Minnesota.
Glossy buckthorn (Frangula alnus), also from Europe, has been sold by the nursery trade in two different forms. The cultivar Columnaris has a narrow and tall form; the cultivar Aspenifolia spreads up to 10 feet and has narrow leaves that give it a ferny texture. This buckthorn aggressively invades wetlands including acidic bogs, fens and sedge meadows.
Why is buckthorn such a problem?
•Out-competes native plants for nutrients, light, and moisture
•Degrades wildlife habitat
•Threatens the future of forests, wetlands, prairies, and other natural habitats
•Contributes to erosion by shading out other plants that grow on the forest floor
•Serves as host to other pests, such as crown rust fungus and soybean aphid
•Forms an impenetrable layer of vegetation
•Lacks “natural controls” like insects or disease that would curb its growth