Buckthorn berries are not safe for consumption. The small, dark fruits produced by the invasive species Rhamnus cathartica and Frangula alnus are toxic to humans and many animals. These berries contain potent chemical compounds that function as powerful purgatives, violently stimulating the digestive system. Understanding the plant’s appearance and toxicity mechanism is important for public safety.
Identifying Buckthorn Species
The two most common invasive buckthorn species in North America are Common Buckthorn (Rhamnus cathartica) and Glossy Buckthorn (Frangula alnus). Both produce dark fruit but have distinct physical characteristics. Common Buckthorn is typically a large shrub or small tree reaching up to 25 feet in height. Its leaves are oval, dark green, and have finely serrated edges, often appearing in sub-opposite arrangements. This species is unique for having a short, sharp spine or thorn at the tip of its twigs and a vibrant yellow-orange inner bark when scraped.
Glossy Buckthorn, also known as Alder Buckthorn, is usually a thornless shrub with a different leaf structure. Its leaves are alternate, shiny, and have smooth margins, lacking the serrated edges of Common Buckthorn. A distinguishing feature is the prominent, parallel veins that curve toward the leaf tip, giving the leaves a ribbed appearance. Both shrubs produce berries that ripen to a deep purplish-black color in late summer or fall. These dark berries are round, small (about a quarter-inch in diameter), and grow in clusters near the base of the leaves.
The Chemical Reason for Toxicity
The toxic nature of buckthorn berries and bark stems from anthraquinone glycosides. These chemicals are the plant’s natural defense mechanism and cause the severe laxative effect. When consumed, these anthraquinone glycosides enter the gastrointestinal tract in a relatively inactive state.
The chemical structure changes when the compounds reach the large intestine and are metabolized by intestinal flora. Bacterial enzymes perform hydrolysis, separating the sugar portion from the anthraquinone molecule. This process converts the anthraquinone glycosides into their active metabolites: anthrones and anthranols.
Anthrones and anthranols are highly irritating to the lining of the colon, triggering a powerful physiological response. They stimulate the nerve endings in the gut wall, which increases the rhythmic muscular contractions known as peristalsis. This increased motility rushes intestinal contents through the digestive tract. These metabolites also interfere with water and electrolyte absorption in the colon, increasing the fluid content of the stool and causing the characteristic purgative effect.
Symptoms Following Ingestion
Consuming buckthorn berries results in a rapid and intense reaction focused on the digestive system. Immediate symptoms include severe abdominal cramping, intense nausea, and violent vomiting. The powerful purgative action of the anthraquinones then leads to significant diarrhea.
The severity of the reaction relates directly to the amount of berries consumed and the size of the individual. Children and small pets are at a heightened risk because a smaller dose represents a higher concentration of toxin relative to their body weight. Although the symptoms are intensely uncomfortable, they usually resolve within 24 to 48 hours as the body expels the toxic material.
The rapid loss of fluids through vomiting and diarrhea can lead to dehydration and an electrolyte imbalance. Anyone who has ingested buckthorn berries, particularly children, should be monitored closely for signs of severe dehydration, such as lethargy or reduced urination. Immediate consultation with a medical professional or contact with a regional Poison Control Center is advised following any known ingestion.
Common Look-Alikes and Misidentification
Buckthorn berries are often mistaken for the fruit of several non-toxic or edible native shrubs, posing a risk for accidental ingestion during foraging. One frequent confusion is with Chokecherry (Prunus virginiana) berries, which are edible when processed. A key difference is fruit arrangement: Chokecherry fruit grows in long, drooping clusters called racemes, while buckthorn berries are found in small clusters near the base of the leaves. Furthermore, Chokecherry fruit contains a single large pit, whereas buckthorn berries contain two to four small, hard seeds.
Another dark fruit that causes misidentification is the Black Chokeberry (Aronia melanocarpa). Although Black Chokeberry leaves can appear similar to Common Buckthorn, they have tiny, dark glandular hairs along the midrib that are absent on buckthorn leaves. Invasive Honeysuckle shrubs (Lonicera species) are also frequently mistaken for buckthorn. Honeysuckle berries are typically red or orange and grow in distinct, paired arrangements, unlike the single, dark berries of buckthorn. Learning these specific identifying features ensures that only safe plants are consumed.