Where it came from
Europe, western Asia, and North Africa; glossy buckthorn from Europe and western Asia.
How it got here
Common buckthorn was brought over as a hedge plant in the early 1800s and sold for shelterbelts and living fences into the 1930s. Glossy buckthorn was planted for wildlife and windbreaks.
What it does to the ecosystem
Both leaf out early and hold leaves late, casting shade that eliminates the ground layer. Buckthorn litter raises soil nitrogen and favors invasive earthworms. Birds eat the berries and drop the seeds far and wide; the berries are often said to act as a laxative on birds, though extension experts disagree on how much that matters. Common buckthorn is the overwintering host of soybean aphid; glossy buckthorn hosts oat crown rust.
What it costs
Agricultural losses from the pests it harbors, plus decades of removal work in Midwestern and Northeastern woodlands.
Don’t confuse it with
- Alder-leaved buckthorn and Carolina buckthorn (native). Natives lack the thorn at the twig tip and have finely toothed leaves; common buckthorn leaves have three to five curving veins and sub-opposite arrangement, and glossy buckthorn has smooth, glossy, untoothed leaves.
How to identify it
Small trees with dark bark, sometimes a thorn at the twig tip, glossy leaves that stay green late into fall, and clusters of black berries.
What to do
Pull small plants; cut and treat stumps of large ones. Prioritize shrubs with fruit: only female common buckthorns fruit, but every glossy buckthorn can.
On Long Island
Scattered in North Shore woodlands and wet thickets. Cut and treat stumps; pull seedlings.
Worth knowing
- The berries were once the source of a yellow-green dye called sap green used by medieval illuminators.
- Common buckthorn has separate male and female plants, so only females fruit. Glossy buckthorn flowers have both parts, so every shrub can fruit. Either way, fruiting shrubs stand out in fall with their berry clusters; prioritize those.
- New York prohibited sale of both species in 2015.
