A growing and reproducing machine, common buckthorn is, so to speak, a nearly perfect invasive plant. It tolerates a wide variety of environmental conditions, including shade and wet or dry sites. It grows quickly. It forms dense stands that crowd out everything else, including native plants. It produces copious berries that are eaten by birds and other animals that then spread the seed to the four corners. There is even evidence showing that common buckthorn is allelopathic—producing chemicals that inhibit the growth of other plants. It’s a doomsday invasive plant.
Once you see common buckthorn you won’t forget what it looks like. There are plenty of clues. The leaves stay green and persist into late fall and even early winter. In the spring common buckthorn leafs out early. In summer and fall clusters of dark-purple or nearly black berries cover the branches. Twigs may have a thorn at the tip. Inner bark is orange.
Effective control includes removal of fruit-producing plants, mechanical pulling of seedlings, and, often, targeted application of herbicide to the cut surfaces of stumps. These processes will likely need to be repeated multiple times.