The problem is extensive in the metro area, the southeast, and many other parts of the state. Wood lots, trails, roadsides, and back yards can have heavy infestations. Originally imported as an ornamental, it has not been sold since the 1930s, when it was found to be a carrier of oat crown rust, an oat disease. Several Twin Cities nurseries have voluntarily stopped selling this tree because of its ability to escape cultivation. A problem in wetlands, glossy buckthorn will also spread into upland sites.
European buckthorn has small alternate simple leaves, black berries, and a flaky bark.
The side branches have short terminal spurs, or thorns, which are literally a pain if you try to remove the plant. Glossy buckthorn has leaves similar to those of European buckthorn, but it has smooth bark and no spurs. The fruits are less numerous than those of European buckthorn. During the summer, buckthorns sometimes resemble a number of small trees, including wild plum and some cherry trees. Fall is the easiest time to identify buckthorn.