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Common Buckthorn (Rhamnus cathartica) is a Eurasian shrub or small tree introduced to North America and now highly invasive across many regions.
Identification
Common buckthorn typically has dark glossy leaves with several pairs of curved veins, small greenish flowers, dark berries, and often a short thorn at twig tips. It can form dense thickets that displace native plants.
Historical Use
The berries and bark were historically used as strong cathartic laxatives. The species name cathartica reflects that reputation.
Toxicity & Safety
Common buckthorn is not an appropriate casual laxative or food plant. Berries and bark can provoke severe gastrointestinal irritation, cramping, vomiting, and diarrhea. Children and pets should be kept from ingesting the berries.
Invasive & Legal Status in Illinois
In Illinois, Rhamnus cathartica is officially listed as an exotic weed. Under the Illinois Exotic Weeds Act and implementing rules, buying, selling, offering for sale, distributing, or planting seeds, plants, or plant parts of listed exotic weeds requires a valid Illinois Department of Natural Resources permit. This is more precise than saying simple possession is universally illegal. Other states and municipalities have their own invasive-species rules, so local law should be checked before sale, distribution, or planting.
Ecology
Common buckthorn leafs out early and retains leaves late, shades native understory plants, alters soils, and spreads readily through bird-dispersed fruit. Removal is generally favored over cultivation where it is invasive.
Historical Context
Its medicinal history illustrates why an old materia-medica plant can become environmentally problematic when introduced far outside its native ecological range.
Educational information only. This article does not recommend internal use or cultivation where restricted.