Buckthorn is an invasive species manger's worst nightmare. This plant can grows incredibly fast, spreads by dispersal of birds, and can regenerate or reproduce underground. Unfortunately to make the problem even worse there are actually two different species of buckthorn. One is known as Common buckthorn, and the other is Glossy buckthorn. To tell the difference would be easiest in the leaves. Below are some resources on how to tell the difference. These plants were introduced to act as privacy hedges however now they take over forests and and swamp habitats. The plant produce black-purple berries that you may see birds commonly eating. However the berries provide little nutritional value to the native birds and actually can make the birds very sick. This eventually spread the seeds into new forests, or protected areas. Not only that but it can be very expensive to treat because once an individuals starts producing seeds they can remain dormant for several years. The seeds can germinate very successfully without any kind of disturbance necessary unlike many other invasive plant species.