I first encountered buckthorn when I volunteered for prairie and savanna restoration in the Cook County, Illinois, Forest Preserve District. A dense, nearly impenetrable cover of buckthorn shrubs had completely shaded our native prairie and savanna plants. But after many years of cutting, applying herbicide and burning massive buckthorn brush piles, the forest preserves now offer expansive vistas of beautiful prairies and savannas.
That buckthorn was called “common buckthorn.” The species we have in Beverly Shores is glossy buckthorn (Frangula alnus), but it is just as threatening. You will most often see glossy buckthorn growing in moist soil. It grows along Beverly Drive and in wetlands and woodlands throughout Beverly Shores. Glossy buckthorn is such a concern that it is illegal, without a permit, to sell or plant it in Illinois under the Illinois Exotic Weed Act. It is a “restricted noxious weed” in Minnesota and “restricted” in Wisconsin.” These are just the states nearest to us. Many states have restrictions on glossy buckthorn. Numerous organization condemn the plant and the Indiana Department of Natural Resources lists glossy buckthorn as an “invasive.” In Indiana you are still free to buy, sell and plant this invasive shrub, but please don’t. Like so many invasives, glossy buckthorn has few natural enemies, produces many viable seeds distributed by birds and animals, and spreads rapidly. It is also shade tolerant, readily re-sprouts if cut down, and out competes and overcrowds our native plants.
Recognizing glossy buckthorn can be challenging until it has become so abundant that it is almost too late. Buckthorn has small, oblong leaves with no serration or teeth on the edges. The leaves are glossy on the upper surface and dull on the lower surface. The leaf veins are prominent, occurring in eight or nine pairs. While these prominent leaf veins are what make it immediately recognizable to me, it takes some practice to see them. The leaves are arranged alternately on the stems (not in pairs). The berries are red this time of year but gradually ripen to deep purple or black and occur along the stems and not in clusters at the stem tips. The flowers are quite small and indistinct with five greenish white petals.
Don’t confuse glossy buckthorn with our beautiful and less common native, winterberry (Ilex verticillata) to which it bears a superficial resemblance. Winterberry has very fine teeth on the leaves and the fruit appears in bright red clusters close along the stem. Winterberry is a prized native, good for birds and wildlife, and pleasing to the eye.
To control buckthorn, it is easiest to remove it when the plants are small and can be pulled out by hand. But populations are often discovered much later than that. Cut larger shrubs down to a short stump and apply Roundup or another glyphosate-containing herbicide to the stump. Be sure to carefully follow all label directions for the herbicide, as required by state and federal law. If the glossy buckthorn is in a wetland, be sure to use a glyphosate product that is labeled for use near or in wetlands.
For native replacements of glossy buckthorn, besides for winterberry, already mentioned, try red osier dogwood (Cornus sericiea) whose red stems provide interest all year around. It also does well in moist soils.
The Environmental Restoration Group (ERG) will be glad to help identify plants for you and make suggestions for removal and for native replacements. Don’t hesitate to contact Terry Bonace (firstname.lastname@example.org), Candice Smith (email@example.com), or Bill Schaudt (firstname.lastname@example.org) for assistance.