Buckthorn berries are toxic and not edible for humans, leading to adverse health effects if consumed. They contain anthraquinone glycosides, including emodin and rhamnicin, which are responsible for their purgative effects. Ingesting even small quantities of these berries can lead to significant gastrointestinal distress.
The Inedibility of Buckthorn Berries
Common symptoms of buckthorn berry ingestion include severe nausea, vomiting, abdominal cramps, and diarrhea. These reactions can be quite intense, making the berries an effective laxative. In some cases, the glycosides in common buckthorn may contribute to liver inflammation and jaundice, with potential for progressive liver damage over time.
Both common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus) produce berries that are toxic to humans. While birds consume these berries and disperse the seeds, the berries offer poor nutritional value and can have a strong laxative effect on them as well. This laxative property contributes to the plant’s rapid spread in various environments.
Identifying Buckthorn Varieties
Common buckthorn (Rhamnus cathartica) is a deciduous shrub or small tree, typically growing between 10 to 25 feet tall. Its leaves are dark green, oval-shaped with finely serrated edges, and have 3 to 5 pairs of prominent veins that curve towards the leaf tip. The bark is gray to brown, often rough, and a distinguishing feature is its bright orange inner bark when cut. Common buckthorn twigs often have a sharp thorn at their tips. Its berries are small, round, and ripen from green to purplish-black, typically appearing in dense clusters.
Glossy buckthorn (Frangula alnus) can also reach heights of 15 to 20 feet and up to 10 inches in diameter. Its leaves are oval, smooth, and glossy with untoothed margins, featuring 8 to 9 veins that radiate from a central mid-vein. Unlike common buckthorn, glossy buckthorn twigs generally do not have terminal thorns. The bark is brown with elongate silvery corky projections, and its cut stems reveal orange heartwood and yellow sapwood. Berries on glossy buckthorn ripen from green to red, then to dark purple or black, and are often found in clusters with a mix of ripened and unripened fruits.
Both varieties can be found in a wide range of habitats, including woodlands, roadsides, and disturbed areas, with glossy buckthorn often preferring moist to wet sites.
Buckthorn’s Broader Environmental Impact
Buckthorn species, particularly common buckthorn and glossy buckthorn, are recognized as invasive plants across North America. They were introduced from Europe and Asia as ornamental plants and for hedgerows.
Their aggressive growth and early leaf-out in spring, coupled with late leaf retention in fall, allow them to outcompete native plants for sunlight and resources. This creates dense thickets that reduce the abundance and diversity of native species, including wildflowers and tree seedlings.
Buckthorn also alters soil chemistry, increasing nitrogen levels and potentially impacting soil moisture and pH. These changes can favor other invasive species and make it difficult for native plants, which are adapted to different soil conditions, to re-establish.
The plant provides poor habitat and food for native wildlife, as its berries are low in nutritional value. Management efforts, such as manual removal or targeted cutting, are necessary to control its spread and mitigate its negative ecological effects.