By Max Kornetzke, land manager

Originally brought to North America as a quick growing hedgerow, common buckthorn (Rhamnus cathartica) is one of the more menacing plants you will encounter invading natural spaces across Wisconsin and the Northeastern part of the country. It has sharp thorny spikes, dark green, serrated, oval leaves, and inconspicuous green flowers in spring that lead to hundreds of dark blue-black berries in late summer and early fall. Seeds can be dispersed by birds, but they make for poor quality food. The berries produce laxative effects that help spread seed further into our natural areas. They’re also low in protein and high in carbohydrates.

If left alone, it will create dense monocultural stands with some individuals becoming small trees with scaly bark that look somewhat similar to the mature black cherry. It is also allelopathic, meaning it produces compounds that prevent other species seeds from germinating.

Recently, research out of University of Minnesota has helped dispel some common myths about common buckthorn, namely, that the seed bank is long lived. Researchers have found that once fruit bearing trees are cut and light is able to hit the ground, the majority of those blue-black berries will germinate within the first year, with the rest mostly germinating within the second.  This is hopeful news for those looking to make an impact on buckthorn infestations and promote native plant diversity. With data that shows a shorter-lived seed bank, more people should feel encouraged to start working on what can seem like a daunting project.

If you’re interested, you can read more about this research here: Uprooting decades of buckthorn management practices: no long-lived seedbank | Minnesota Invasive Terrestrial Plants and Pests Center (umn.edu).

If you’re looking to offer food options that are healthier for birds and the environment, consider planting native shrubs and small tree species such as black chokeberry (Aronia melanocarpa), chokecherry (Prunus virginiana), elderberry (Sambucus canadensis), Service berries (Amelanchier sp.), or dogwoods (Cornus sp.).

Photo of common buckthorn by Ian Redding