Buckthorn: How to identify, remove invasive plant

By Tom Boisvert

Conservation Program Manager, Lincoln County Conservation Department

MERRILL – So what is buckthorn anyways?

Buckthorn is an invasive plant that most commonly looks like a shrub, but once mature can form into a small tree. There are two main varieties of buckthorn that are of concern in Wisconsin: common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus).

In general, common buckthorn tends to invade forest understories and other upland settings, while glossy buckthorn tends to invade wetter settings which may include lowland and some wetland habitats. Both common and glossy buckthorn can reach heights of 10 to 25 feet and create a dense canopy that allows for little to no forest undergrowth. Beyond this, simply walking through a patch of the stuff can be a nightmare.

Besides limiting forest undergrowth, these plants also provide very little value to wildlife. The berries from buckthorn appear to be enjoyed by birds; however, they actually act as an uncomfortable laxative, which causes the seeds to spread easily. These berries also release a toxin into the soil that limits other plant growth – a process similar to black walnut trees.

Fall is a great time to assess if you have buckthorn on your property. Buckthorn stays green and holds on to its leaves late into the fall, when most other plants have already dropped their foliage. This unique characteristic of buckthorn makes it very easy to locate and confirm they are buckthorn before treatment.

Buckthorn is recognized by its dark green round leaves and red-to-black berries, and occasional terminal thorns (see photo).

Young buckthorn sprouts can be hand-pulled, and treatment of older buckthorn can include a variety of methods, including mechanical and herbicidal. To help determine what treatment method is best, the Wisconsin Headwaters Invasives Partnership (WHIP) can assist in this process.

WHIP coordinator Rosie Page can be reached at [email protected]. WHIP may also be able to assist with the control of buckthorn on your property. By removing buckthorn on our properties, we are all contributing to a healthier, more diverse and more enjoyable forest landscape.

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