Common Name: Common buckthorn, European buckthorn
Scientific name: Rhamnus cathartica
Identification: Common buckthorn is a tall shrub to small tree that can reach up to 25’ in height with one to multiple stems. Leaves are oval, 1 – 2 ½” long, are finely toothed along the edges, and have 2 – 3 pairs of prominent veins curving toward the leaf tip. The leaves can be directly opposite each other, nearly opposite, or alternate. The bark is gray to brown with prominent, dark, eye-shaped pores called lenticels, becoming roughened with age. Cutting the bark exposes yellow sapwood and orange heartwood. Twigs often end in sharp spines that are 1/5 – 9/10” long. Common buckthorn is most frequently dioecious, meaning that male and female flowers usually occur on different plants. However, male and female flowers are very similar in appearance. They emerge in the spring in clusters of 2 – 6 and have four pale green petal-like sepals. Each flower is ¼” in diameter. Inflorescences are fragrant. Abundant clusters of round, pea-sized fruit appear green on female plants in July to August, ripening to black in early fall. Fruits contain 3-4 seeds and can remain on plants into winter (Dirr 2008, Hilty).
Look-alikes: Common buckthorn can look similar to invasive glossy buckthorn (Frangula alnus). It can be differentiated by its spines (absent on glossy buckthorn) and finely toothed leaf edges. There are two species in the Rhamnus genus that are native to parts of the Great Lakes Basin. They are alder-leaved buckthorn (R. alnifolia), and lance-leaved buckthorn (R. lanceolata). Alder-leaved buckthorn is smaller than common buckthorn, only reaching a maximum of 3’ in height at maturity. Its flowers have five petals rather than four and it has small green appendages at the base of each leaf stem called stipules, which common buckthorn does not have. Lance-leaved buckthorn has a longer and narrower leaf shape, more than three pairs of veins, and more pointed leaf tips when compared to common buckthorn (Hilty).
Common buckthorn is reported frequently across the entire Great Lakes region. On a continental scale it is most common in the Great Lakes region and Northeastern U.S., but is also found in the Mid-Atlantic, northern Great Plains, and on the West Coast. Common buckthorn is considered hardy to Zone 3, but populations have been observed to tolerate temperature extremes from 104 °F to -53 °F (Zouhar 2011). It is often found near urban areas where it was used as an ornamental plant.
Additional invasive species distribution data for specific Great Lakes jurisdictions is available via:
- Midwest Invasive Species Information Network (Michigan)
- iMapInvasives (New York and Pennsylvania)
- EDDMapS Ontario
Buckthorn seeds are spread over distance by birds that eat the fruit.
Common buckthorn invades many plant communities in the Great Lakes region including oak forests, woodlands, savannas, prairies, riparian areas, and wetland edges. It has a preference for disturbed sites, and is frequently a problem in urban parks, bike trails, and forest preserves. However, it can also establish populations in less disturbed natural areas. Areas with high populations of non-native earthworms may be particularly vulnerable to invasion by common buckthorn (Heneghan et al. 2007).
Once established, common buckthorn maintains large populations through prolific seed production and high rates of germination, even under shade. It out-competes other plant species by growing very quickly and by leafing out very early in the spring and retaining its leaves late into the fall, effectively extending its growing season. Its biological advantages often allow common buckthorn to form a dense single-species stands that prevent regeneration of native species. Buckthorn also alters its habitat to favor its own growth by influencing nitrogen cycling (Heneghan et al. 2006). It may also exude chemicals that prevent the germination of some native plant species (Warren et al. 2017, Klionsky et al. 2010). Its chemical activity may also prevent native amphibian eggs from hatching, further disrupting ecosystems (Sacerdote and King 2014). Buckthorn also appears to negatively impact the bird species that use it for nesting and food (Knight 2005).
Common buckthorn negatively impacts agriculture by acting as a host for crop pests. It is a known host plant of crown-rust, a fungal disease of oat crops, and the soybean aphid. Without treatment, soybean aphids can reduce soybean crop yields by 26% (Kim et al. 2008).
Common buckthorn was introduced to the U.S. in the early 1800s for use as an ornamental shrub and small tree in parks and gardens. It was also often recommended for wildlife habitat plantings, hedges, and windbreaks until it was recognized as an alternate host for the oat crown rust fungus (Archibold et al. 1997). It was recognized as naturalizing in the upper Midwest and northeastern parts of North America in the early 1900’s (Knight 2005). Today, common buckthorn is broadly recognized as an invasive species and is no longer available in trade. However, it persists as a legacy of past planting in many urban areas. The 2010 Chicago-area census of urban trees found that common buckthorn accounted for 28.2% of the trees in the region (Nowak et al. 2012).
None. Male common buckthorns do not produce fruit, but there are no male cultivars in trade.
Please see our Landscape Alternatives pages for more information about how the WIGL Collaborative selected alternatives.
|Alternatives for Common Buckthorn
Common name (Latin name)
|Tall shrub or small tree;
good for screening
good for hedging
|Fruit attracts birds||Very cold-hardy
|American hornbeam (Carpinus caroliniana)||✔||✔||✔|
|American hazelnut (Corylus americana)||✔||✔|
|Northern spicebush (Lindera benzoin)||✔||✔|
|Alder-leaved buckthorn (Rhamnus alnifolia)||✔||✔||✔|
|American arborvitae (Thuja occidentalis)||✔||✔||✔||✔|
|Arrowwood viburnum (Viburnum dentatum)||✔||✔||✔|
|Blackhaw viburnum (Viburnum prunifolium)||✔||✔||✔|
|Carolina allspice (Calycanthus floridus)||✔||✔|
|Vernal witchhazel (Hamamelis vernalis)||✔||✔||✔|
|Boxwood (Buxus sp.)
|Sweetshrub hybrid (Calycanthus x)
|Blood-twig dogwood (Cornus sanguinea)
‘Cato’ ARCTIC SUN™, ‘Winter Flame’
|Anglo-Japanese yew (Taxus x. media)
~ = trait is somewhat present but not as pronounced as in check-marked examples
a ‘Green Mountain’ is a tall boxwood cultivar and may eventually grow to 7’, though it is slow-growing
bAnglo-Japanese yew is sold as dioecious (male or female) clones, and only the females will produce fruit. ‘Densiformis’ is female.
Green = native to part of the Great Lakes Basin
Yellow = native to the United States but not to the Basin
Blue = not native but not invasive
The WIGL Collaborative’s decision trees are designed to help site users, who are perhaps newly discovering that plants that are part of their home landscaping are invasive, prioritize which species should be removed first based on risk to the surrounding environment, economy, and occasionally, to human health. In a perfect world, everybody would remove all invasive plants from their landscaping right away, but in reality, removing mature woody plants involve a hefty investment of time and/or money. These diagrams can help people with multiple woody invasives in their landscaping prioritize to get the most benefit for their efforts.
To learn more about the methodology and information used to develop the decision trees and for helpful hints on how to answer the questions, please see the full report here (PDF).
The following is a brief overview of management techniques shown to be effective on common buckthorn. For more detailed information on how to use these techniques, please visit our Control and Management page. For technical assistance with managing woody invasive species, please get in touch with a local cooperative invasive species management group or university extension program.
Timing and spread concerns: Whenever possible, individual plants should be controlled before they are able to fruit in order to prevent spread. If resources are limited, managers might prioritize removal of female plants to prevent further spread. If control is undertaken after plants have fruited, it is best not to remove the plants from the site to avoid spreading seed.
Physical control: Small plants are easily hand-pulled from moist soil; larger plants can sometimes be dug or pulled using equipment. The root crown must be removed to prevent regrowth. Top-killing methods such as mowing, grazing, and prescribed fire are rarely effective by themselves unless repeated multiple times a year for multiple years. However, top-killing methods followed by foliar herbicide treatment of regrowth can be highly effective (see combined approaches below).
Some landowners are experimenting with a non-chemical variation on the cut stump method for common buckthorn where the freshly cut stump is covered with a tin can or fully opaque plastic bag instead of applying herbicide. If installed correctly and left in place for one to two years, this method can prevent regrowth by blocking light to the cut surface (Minnesota Department of Natural Resources). If light is blocked for long enough, the roots will eventually die.
Chemical control and combined approaches: Foliar spray is the most feasible method for managing a large, dense buckthorn infestation, and is effective anytime plants are actively growing and fully leafed out. Foliar application can also be used as a follow-up to mowing or grazing when foliar herbicide is applied to regrowth later in the season or during the subsequent season. Cut stump, basal bark and stem injection herbicide treatments are all effective on buckthorn and can be applied during most of the year outside of early spring. In all cases, herbicide should be selected carefully based on site conditions, and label directions read and followed carefully.
With any treatment it will be necessary to monitor for and treat regrowth in subsequent years. This is especially true for common buckthorn whose seeds persist in the soil for a number of years. Managers should expect treatment of dense buckthorn infestations to be a long-term commitment.
Resources on management of common buckthorn:
- Archibold OW, Brooks D, and L Delanoy. 1997. An investigation of the invasive shrub European Buckthorn, Rhamnus cathartica L., near Saskatoon, Saskatchewan. Canadian Field-Naturalist, 111(4):617-621.
- Dirr, MA. 1998. Rhamnus cathartica. In: Manual of Woody Landscape Plants, Fifth Edition. Champlain, IL: Stipes Publishing. 839-840.
- Heneghan, L, Steffen, J, and K Fagen. 2007. Interactions of an introduced shrub and introduced earthworms in an Illinois urban woodland: Impact on leaf litter decomposition. Pedobiologia 50(6): 543-551.
- Heneghan, L, Fatemi, F, Umek, L, Grady, K, Fagen, K and M Workman. 2006. The invasive shrub European buckthorn (Rhamnus cathartica L.) alters soil properties in Midwestern U.S. woodlands. Applied Soil Ecology 32(1): 142-148.
- Hilty, J. Rhamnus cathartica. In: Illinois Wildflowers. 4/10/20.
- Kim, CS, Schaible, G, Garrett, L, Lubowski, R, and D Lee. 2008. Economic impacts of the U.S. soybean aphid infestation. Agricultural and Resource Economics Review. 37(2): 227-242.
- Klionsky, SM, Amatangelo, KL, and DM Waller. 2010. Above- and belowground impacts of European buckthorn (Rhamnus cathartica) on four native forbs. Restoration Ecology 19(6): 728-737.
- Knight, KS. 2005. Buckthorn biology and invasion history. In: Proceedings: Symposium on the Biology, Ecology, and Management of Garlic Mustard (Arrialia petiolata) and European Buckthorn (Rhamnus cathartica). St Paul, MN: USDA Forest Service. 30-33.
- Minnesota Department of Natural Resources. Buckthorn management. 1/22/19.
- Nowak, DJ, Hoehn, RE III, Bodine, AR, Crane, DE, Dwyer, JF, Bonnewell, V, and G Watson. 2012. Urban Trees and Forests of the Chicago Region. Newtown Square, PA: United States Forest Service, Northern Research Station.
- Sacerdote, AB and RB King. 2014. Direct effects of an invasive European buckthorn metabolite on embryo survival and development in Xenopus laevis and Pseudacris triseriata. Journal of Herpetology. 41(1): 51-58.
- Warren II, RJ, Labatore, A, and M Candeias. 2017. Allelopathic invasive tree (Rhamnus cathartica) alters native plant communities. Plant Ecology. 218(10): 1233-1241.
- Zouhar, Kris. 2011. Rhamnus cathartica. In: Fire Effects Information System (Online). U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. 1/22/19.
Photo: Rob Routledge, Sault College, via bugwood.org