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Common buckthorn

(Rhamnus cathartica)

Photo of Common buckthorn
Photo credit: Wisconsin DNR

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.

Overview map of common buckthorn classification in WI
Restricted (orange) counties

Other names for this plant include:

  • Common names: Carolina buckthorn, European buckthorn

Classification in Wisconsin: Restricted

Ecological Threat
  • 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.
  • Creates dense shade, eliminating the regeneration of tree seedlings and understory species.
  • Allelopathic; produces chemical compounds that inhibit the growth of other vegetation.

Leaves & stems: Ovate or elliptic, with prominent veins curving toward the tip. Mostly opposite leaves, 1-2.5” long, with tiny teeth. Leaves remain on plants and stay green into fall. The bark is gray to brown with prominent light-colored lenticels. Cut bark exposes an orange inner cambium layer.

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. Birds and mammals disperse them. Fruits remain on plants into winter after all the leaves have fallen.

Roots: Extensive, black fibrous root system.

Similar species: Glossy buckthorn (Rhamnus frangula; invasive) is identical to common buckthorn. Leaves are mostly opposite, with a more significant number of veins. The upper surfaces of leaves are shiny with the 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.

  • Small plants may be hand-pulled and prescribed fire for seedlings. Larger plants can be dug or pulled using a leverage tool such as a weed wrench.
  • Girdling trees require stripping the bark to expose the inner hardwood at a minimum of six inches. Adequate any time of year.
  • 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.

For more information on control techniques, visit the Common buckthorn factsheet [exit DNR] by the University of Wisconsin-Extension.

Sources for content:
  • Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. The University of Wisconsin Press. 2005. Pg. 35-41
  • University of Wisconsin-Extension. Common buckthorn factsheet [exit DNR].
Links for more information: