The leaves of Rhamnus cathartica are simple and finely toothed and may be arranged both alternately and oppositely on the same branch. The small thorns at the tips of most branches are unique among our trees. The dark colored fruits are juicy with several seeds inside.

Rhamnus cathartica is a troublesome invasive species introduced from Europe. It is found throughout Wisconsin, although it is more numerous in the south. The incomplete distribution shown on the map is in part a function of its rapid, recent spread. The fruits are eagerly eaten by birds and the seeds are thereby spread widely. When the trees reach maturity they produce abundant fruit and within a few years there are commonly thousands of seedlings around the base of each mature tree. Cut stumps sprout vigorously.