An exotic invasive species that you will see throughout the park is common buckthorn. Buckthorn was brought to the United States from Europe to be used as a shrub or hedge and has taken over in many forested areas throughout the United States. Buckthorn plants are shrubs or small trees that produce a dense thicket and often can be seen lining the pathways through the park like a wall of green. These plants grow into what is called a monoculture where one plant predominates and ruins the biodiversity of the area. Buckthorn plants produce dark blue berries that birds eat and spread the seeds through their droppings. You can identify buckthorn plants later in the fall as their leaves remain green and on the plant long after other plants have lost their leaves. These plants secrete substances from their root
systems that inhibit the growth of other plants. Removing buckthorn allows the seed bank in that area to then germinate. Buckthorn is difficult and costly to remove and efforts to control it can be seen in various areas throughout the park. Stacks of cut branches are signs of buckthorn removal efforts. The Friends of Sunfish Lake Park hold periodic volunteer buckthorn removal events to control the spread of buckthorn in the park. For more information on how to volunteer, call or text George at 651-757-5610.

Buckthorn leaves are rounded, with a finely toothed edge, have a central main vein with a half-dozen branches, and attached to the stem not quite across from each other. Buckthorn berries are blackish-blue and occur only on female trees.