buckthorn

Buckthorn is a common name for several shrubs and small trees in the genera Rhamnus and Frangula. The best-known species are common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus; formerly Rhamnus frangula). Native to Europe and western Asia, many buckthorn species have become invasive in North America and elsewhere, where they can form dense thickets in woodlands, wetlands, and along edges.

Buckthorn species are deciduous and typically 3–9 m tall, with simple, oval leaves. Rhamnus cathartica often has finely serrated margins and distinct venation; Frangula alnus has glossy leaves with entire margins. Flowers are small and inconspicuous in spring; berries mature from green to black or dark purple in late summer or autumn. Fruits are eaten by birds, aiding dispersal.

In introduced ranges, buckthorn forms dense understories that shade native shrubs and saplings, reducing forest regeneration and altering wildlife habitat. It can modify soil moisture and microbial communities, and its shade tolerance helps it persist after canopy gaps. Birds disperse berries widely, contributing to rapid spread.

Early detection and removal are advised. Small plants can be pulled; larger plants may require cutting and treating stumps or repeated cutting to exhaust the root system. Follow-up is needed to prevent resprouting. Avoid spreading berries by cleaning equipment and clothing. Buckthorn berries are mildly toxic to humans and pets if ingested.