Common buckthorn or European buckthorn (Rhamnus cathartica) and glossy buckthorn (Rhamnus frangula or Frangula alnus) originated in Eurasia and were brought to the Midwest to be used as hedges and for landscaping. Both species have a long growing season and a dense growth pattern that allows them to out-compete native vegetation. In the fall the yellow leaves on buckthorn plants are easily seen in the understory after most other plants have dropped their foliage. Buckthorn produces many dark berries that either drop to the ground and germinate or are eaten by birds and small mammals and spread across the landscape. Common buckthorn grows in open woodlands and on woodland edges, although it can also be found in prairies, yards, and along roads. Glossy buckthorn can grow in full sun and in heavily shaded areas. Although both species can be found in drier areas, common buckthorn prefers well-drained soils and glossy buckthorn thrives in wet soils. The ability of buckthorns to grow so quickly and in such a wide variety of habitats and soil types makes them particularly concerning exotic invasive species. Additionally, buckthorn is the host plant for soybean aphids, which makes it even more problematic in Iowa. Common buckthorn is listed in Iowa as a primary noxious weed.
Habitat: Both common and glossy buckthorn can be found in a wide variety of habitats from prairies to woodlands though their impacts are greatest in wooded areas.
Hardiness: Zone 3
Mature Shape: Small tree or tall dense shrub
Height: 25 feet
Width: Trunk up to 10 inches in diameter
Site Requirements: Common buckthorn prefers well-drained soils; glossy buckthorn can be found in drier areas but does best in wet soils.
Leaves: Common buckthorn leaves are 1-1.5 inches long, simple, opposite or sub-opposite (occasionally alternate), hairless, round or oval with a pointed tip, and have finely toothed margins. Common buckthorn has 3-4 pairs of veins. Glossy buckthorn leaves are 1-3 inches long, simple, usually alternate, and oblong with smooth margins. Glossy buckthorn leaves have 6-9 pairs of veins.
Flowering Dates: Common: May-June; Glossy: May to first frost
Buckthorn flowers emerge from the leaf axils and are small with white or greenish yellow petals. Common buckthorn flowers have 4 petals and glossy buckthorn flowers have 5 petals. Buckthorn fruit are pea-sized, berry-like, drupes that start out as red and turn black as they ripen in the late summer to early fall. Glossy buckthorn can have branches with fruit in varying stages of ripeness throughout the summer and fall.
Common buckthorn has gray-brown bark that becomes flaky and darker gray-black as the plant ages. Common buckthorn often resembles the bark of plum and cherry trees. Both species have prominent lenticles, yellow sapwood, and pinkish orange heartwood. Common buckthorn has thorns but glossy buckthorn does not.
Removing buckthorn plants early, before they produce fruits is the most effective way to prevent them from spreading. If the plants are still within their first year of growth but there are too many seedlings to remove by hand, prescribed fire in the fall or early spring can be effective. A prescribed fire may need to be performed for two to three years in a row depending if there are seeds in the soil that will sprout the year following the initial burn. Caution should be taken to make sure native plants can tolerate repeated burning. Combining fire with grazing goats can also be effective. Once buckthorn has formed dense thickets, fire is generally not an effective control method. If manual control is not practical, see our Chemical Control of Unwanted Vegetation article for specific herbicides and application methods.