Common Buckthorn
Common buckthorn is a species of small tree in the flowering plant family Rhamnaceae. It is native to Europe, northwest Africa and western Asia. It was introduced to North America as an ornamental shrub in the early 19th century and it is classified as an invasive species.
It is a deciduous, dioecious shrub or small tree growing up to 10 meters (33 ft) tall, with gray-brown bark and often thorny branches.
The seeds and leaves are mildly poisonous for humans and most other animals, but are readily eaten by birds, who disperse the seeds in their droppings.