Common buckthorn | The Morton Arboretum

Common buckthorn is an exotic weed in Illinois. The Illinois Exotic Weed Act prohibits the sale or distribution of this plant in Illinois. This shrub spreads by seed, which is dispersed through consumption by animals. It commonly grows in forests, but can also grow in grasslands, riparian areas, and disturbed sites. It originated in Eurasia, and was introduced to the United States as an ornamental, and today is found across most states in the United States.

Common buckthorn is also an invasive species. An invasive plant is a plant species that is non-native to the location being considered and whose presence and spread negatively impacts (or is likely to impact) ecological, economic or human health. Common buckthorn should not be planted because it can form dense, spreading vegetative thickets that restrict other plants’ access to the sunlight, nutrients, and space that they need for growth. This reduces biodiversity and habitat availability. Data collected at The Morton Arboretum show that this tree is invasive on the Arboretum grounds.

As an alternative, common chokecherry (Prunus virginiana) is a good option for its similar appearance and size. There are a number of native and non-native species that could be used in place of common buckthorn. More desirable species may be found using the online Search Trees and Plants page of the Arboretum website. Before purchasing or planting, be sure to check for any local or state guidelines on these species, and ensure that the plant is suitable for its habitat by checking its attributes at mortonarb.org or plants.usda.gov.

Family (English) Buckthorn
Family (botanic) Rhamnaceae
Tree or plant type Tree, Shrub
Foliage Deciduous (seasonally loses leaves)
Native locale Non-native
Size range Large shrub (more than 8 feet), Compact tree (10-15 feet), Small tree (15-25 feet)
Light exposure Full sun (6 hrs direct light daily), Partial sun / shade (4-6 hrs light daily), Full shade (4 hrs or less of light daily)
Hardiness zones Zone 3, Zone 4, Zone 5 (Northern Illinois), Zone 6 (City of Chicago), Zone 7
Soil preference Acid soil, Alkaline soil, Dry soil, Moist, well-drained soil, Wet soil
Tolerances Alkaline soil, Dry sites, Road salt, Wet sites
Flower color and fragrance Inconspicuous, Orange
Shape or form Multi-stemmed, Round
Growth rate Fast, Moderate

More Information

Size and Method of Spreading

Common buckthorn typically grows to be 15 to 25 feet tall. The broad branches form dense thickets.

Bark Color and Texture

The bark is brown to gray in youth. Rough and slightly peeling, the stems have prominent white lenticels and the interior wood is yellow. Stems often have scattered thorns.

Leaf Description

The green leaves are opposite to sub-opposite, 1 ½ to 3 inches long, and ¾ to 1 ½ inches wide. They are long and oval-shaped (elliptical) with minute teeth on the edges (leaf margins), and a pointed tip. The leaves of buckthorn often remain green well into autumn after other trees have dropped their leaves.

Flower Description

Common buckthorn’s flower heads develop in clusters of small florets near the branches (raceme inflorescence). Each flower is light green, and has four sepals, forming a crosslike (cruciform) shape. Each plant bears either male or female flowers (dioecious), but some may produce perfect flowers, with both genders as well. Flowering time is early summer.

Fruit Description

Female plants bear ¼-inch berrylike fruits (drupes) in clusters. They are green in summer and turn dark blue to black in August.

Related Species

Sharp-Tooth Buckthorn

Sharp-tooth buckthorn (Rhamnus arguta) is an exotic weed and invasive plant in Illinois. This shrub spreads by seed. It commonly grows in wooded areas and disturbed sites. It is found within the Midwest (USDA Zones 5-7). The shrub typically grows to about 10 feet tall. The bark is dark brown, and there are thorns along the stem. The simple, dark green leaves are heavily serrated around the edges, with less distinct venation than common buckthorn. The small flowers are white to light green, and the berrylike drupes are dark blue. Nannyberry (Viburnum lentago) is a good alternative.

Japanese Buckthorn

Japanese buckthorn (Rhamnus japonica) is an exotic weed and invasive plant in Illinois. This shrub spreads by seed. It is found in wooded areas such as forests or disturbed sites. The species is native to Asia, and today can be found throughout Illinois and Missouri. It grows to a height of about 20 feet. The leaves, flowers, and fruit are relatively similar to that of common buckthorn. Common chokecherry (Prunus virginiana) is a good alternative.

Chinese Buckthorn

Chinese buckthorn (Rhamnus utilis) is an exotic weed in Illinois. This shrub spreads by seed. It commonly grows in wooded areas such as forests or disturbed sites. The species is native to China, and today can be found throughout Illinois. The flowers, fruit, and leaves are similar to that of common buckthorn, but the leaves are typically longer. New Jersey tea (Ceanothus americanus) is a good alternative.