Buckthorn

By PAM BERNSTOCK, Ohio Chapter Volunteer

About 78 percent of the 2,300 species of plants in the wild in Ohio are native or occurred in Ohio before the time of substantial European settlement, about 1750. It is the other 22 percent, more than 500, of non-native species that can cause problems when they are invasive. The glossy buckthorn and the common buckthorn (Rhamnus frangula and R. cathartica, respectively) are two non-native, invasive plants that we are battling on our preserves. They are most prevalent in central and northern Ohio.

Buckthorn grows rapidly in a wide range of habitats and many different soil conditions (from well-drained sand to poorly drained clay). Both species of buckthorn can be found in the same habitat, though glossy buckthorn thrives in wetlands - such as swamps, bogs and fens - and common buckthorn tends to grow in lightly shaded upland habitats including woodland edges, forests, fencerows, prairies, and old fields.

The seeds of the buckthorn often fall directly beneath the shrub and, in part because of their shade tolerance, begin to grow. This type of seed deposition leads to dense patches of buckthorn, which makes it difficult for the native shrubs and herbs to find room to grow in the same area. In addition, buckthorn secretes chemicals from its roots which deter other plants from germinating in the surrounding soil. As a result, many native plants are not only sparse, but often completely absent from the habitat. Many native trees are also unable to regenerate in this setting. This causes a problem in fire-adapted ecosystems like savannas and prairies because there isn’t enough proper native vegetation to help spread the much needed fire.

So how did the non-native, invasive buckthorn get here? In America, in the mid-nineteenth century, people’s taste in gardens began to change and become more sophisticated. In response, many nursery catalogs began to offer non-native ornamental plants. One such plant was buckthorn, native to North Africa, Asia and Europe. It became popular because it is such a hardy plant. Gardeners found it to be a good choice for ornamental shrubs for fence rows and wildlife habitats. It is still being used today.

What does it look like? Buckthorns are tall shrubs or small trees that grow up to 20 feet tall. The bark on a mature common buckthorn is rough and peeling and the glossy buckthorn is smooth. Both have what a botanist would call light-colored lenticels, which look like white dashes. Common buckthorn has dull green, smooth leaves and produces black fruits. Glossy buckthorn has shiny leaves with smooth edges and produces solitary red to purple berry-like fruits.

Cutting and treating stumps or spraying foliage with a systemic herbicide is the best method of control. Buckthorns are very difficult to control due to vigorous resprouting and a large seed bank.

Register today to participate in a project battling buckthorn! Come out to the preserves to see the buckthorn in person. This quarter we will be controlling it at Beck Fen, Morgan Swamp and Herrick Fen. Sign-up by mailing in a sign-up form or going to the Volunteer projects and Sign-up page in the Volunteer section of the Ohio Chapter website.