Alder buckthorn (Frangula alnus) is a common shrub or small tree found in wetlands, woodlands, and hedgerows across Europe, northern Africa, and western Asia. It produces small berries that undergo a distinct color transformation as they mature. Accurate identification of these berries is important due to their distinguishing characteristics.
Identifying Alder Buckthorn and Its Berries
Alder buckthorn berries are small and round, typically pea-sized, about 0.25 inches across. They develop through a distinct color progression, starting as green, then transitioning to yellow and red, and finally maturing to a dark purple or black. These berries often appear in clusters along the branches.
The plant is a non-spiny deciduous shrub, usually growing 10 to 20 feet tall. Its oval-shaped leaves are 1.25 to 2.75 inches long by 1 to 1.6 inches wide, with smooth margins and prominent parallel veins that do not curve towards the tip. The bark is dark blackish-brown, revealing a bright lemon-yellow inner bark when cut.
Toxicity and Health Implications
Alder buckthorn berries are poisonous to humans if ingested. They contain anthraquinone glycosides, which act as strong purgatives. The bark and other parts of the plant also contain these toxic chemicals.
Symptoms of ingestion include severe stomach cramps, nausea, vomiting, and diarrhea. These symptoms usually appear several hours after consumption. While not life-threatening for adults in small quantities due to induced vomiting, the symptoms can be distressing, and dehydration is a concern, particularly for children or vulnerable individuals.
If ingestion is suspected, contact a poison control center or seek medical attention immediately. Replacing lost fluids is a primary component of treatment.
Differentiating from Similar Berries
Distinguishing alder buckthorn berries from other black berries is important for safety. Common buckthorn (Rhamnus cathartica) is a related species that also produces toxic berries and can be confused with alder buckthorn. Common buckthorn has finely toothed leaf margins and may have thorns, unlike the smooth-margined, thornless leaves of alder buckthorn. The leaves of common buckthorn are sub-opposite, while alder buckthorn leaves are alternately arranged.
Other black berries, such as elderberries and blackcurrants, might be mistaken for alder buckthorn berries. Elderberries grow in larger, umbrella-shaped clusters, and while their uncooked berries are poisonous, they are processed for consumption. Blackcurrants are found on smaller shrubs, known for their distinct aroma and taste, and their berries are edible. If there is any doubt about the identity of a berry, it should not be consumed.
Ecological Significance and Historical Uses
Alder buckthorn plays a role in its ecosystem, serving as a food source for various birds, which are unaffected by the toxins in the berries and help disperse the seeds. It is also a larval host plant for certain butterflies, such as the brimstone butterfly. Its flowers provide nectar for bees.
Historically, alder buckthorn has served various purposes. Its bark was traditionally used as a strong purgative, though this practice is not recommended due to overdose risks and severe side effects from fresh bark. The wood was highly valued for charcoal production, particularly for gunpowder, due to its even burn rate. Berries were used to produce yellow or green dye, and the bark could yield red or orange dye.