Frangula alnus

An ornamental European species that is considered a level 1 invasive in our region. Birds and wildlife spread the seeds. Shrubby plant that grows to 6 - 24 feet tall with stems up to 10" diameter. The leaves are alternate and there are no "thorns". Its bark is gray to brown with white lenticels. Tends to be in moist-wet disturbed sites and along waterways, but tolerates a wide variety of conditions and forms dense thickets, aggressively crowding out native species. See also Rhamnus cathartica, the common (non-native, invasive) buckthorn.  There is also a native buckthorn (Rhamnus alnifolia), so verify identification prior to removal.