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Common buckthorn (Rhamnus cathartica)
Tall understory shrub or small tree up to 20-25’ tall, often with several stems arising from the base, and spreading crown. Gray to brown bark with prominent light-colored lenticels. (Caution: native plums and cherries have a similar bark). Plants are either male or female. Cut bark exposes yellow sapwood and orange heartwood. Twigs often end in stout thorns.
Common buckthorn is Restricted (Orange counties)
Other names for this plant include:
- Common names: Carolina buckthorn, European buckthorn
- Invades oak forests, riparian woods, savannas, prairies, old fields, and roadsides. It thrives particularly on well-drained soils.
- Common buckthorn has a broad environmental tolerance. It leafs out very early and retains its leaves late into the growing season, giving them a longer growing season than native plants.
- Produces dense shade, eliminating regeneration of tree seedlings and understory species.
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 common buckthorn was based upon this literature review developed by the department.
Leaves: Ovate or elliptic, with prominent veins curving toward tip. Mostly opposite leaves, 1-2.5” long, with tiny teeth. Leaves remain on plants and stay green into fall.
Flowers: Inconspicuous, small and clustered in leaf axils. Fragrant, greenish-yellow, 4-petaled flowers that bloom in spring.
Fruits & seeds: Abundant clusters of round, black, pea-sized fruit. Ripen on female plants in late summer. Dispersed by birds and mammals. Fruits remain on plants into winter after all the leaves have fallen.
Roots: Extensive fibrous root system.
Similar species: Glossy buckthorn (Rhamnus frangula; invasive) is similar to common buckthorn. Leaves are mostly opposite, with greater number of veins. Upper surface of leaves are shiny with undersides dull.
Alder buckthorn (Rhamnus alnifolia; native) is under 3’ tall with thornless twigs. Lance-leafed buckthorn (R. lanceolata; native) is less than 6’ tall, found in wet areas and on dry limestone slopes, and has alternate leaves, 2-6” long, gradually tapering to a point at the tip. Carolina buckthorn (R. caroliniana; native), found in the southern Midwest, is 10-30’ tall with toothed, mostly alternate leaves, 2-3” long.
Counties in WI where common buckthorn has been reported (as of July 2011). Both vouchered and unvouchered reports included.
Do you have common buckthorn in your county but it isn't shaded on the map? Send us a report.
Mechanical: Prescribed fire for seedlings. Small plants may be hand pulled. Larger plants can be dug or pulled using a leverage tool such as a weed wrench. Effective girdling of trees requires stripping the bark to expose the hardwood at a minimum length of six to ten inches. This may need to be repeated.
Chemical: Cut-stump treatment with glyphosate in late fall; cut stump or basal bark spray treatment around the stem with triclopyr ester in late fall through the winter.
View common buckthorn pictures in our photo gallery!
Sources for content:
- Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. University of Wisconsin Press. 2005. Pg. 35-41
- Pennsylvania Department of Conservation and Natural Resources. Species Management and Control Information.
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