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Common buckthorn is an invasive plant in Illinois and should not be planted. It forms dense thickets and reproduces very freely, crowding out other plants and disrupting  ecosystems in forest preserves and other natural areas. In woodlands it can completely replace existing understory plants, including native wildflowers. Buckthorn has berries that are spread by birds.The seeds germinate at a very high rate and remain viable in soil for two to three years. Buckthorn is very common in gardens and yards in the Midwest, but should be removed where it is found. Buckthorn is a large shrub or tall tree with glossy oval leaves that can easily be recognized in fall, when it remains green after most other leaves have fallen. Under the Illinois Exotic Weed Act, buckthorn cannot be sold in Illinois.

  • 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 (Chicago), Zone 6, 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

Native geographic location and habitat:

Native to Europe

Bark color and texture:

The tree’s bark is brown to gray in youth, rough and peeling with prominent whitish lenticels and yellow coloration on the inside. The stems may form dense thickets.

Leaf or needle arrangement, size, shape, and texture:

Leaves are opposite to sub-opposite; 1 ½ to 3” long and ¾ to 1 ½” wide. They are elliptical in shape with minute teeth on margins and rounded to pointed tips. Leaves remain bright green in fall for some weeks after most other shrubs and trees have lost their leaves.

Flower arrangement, shape, and size:

Male and female flowers are on separate plants (dioecious). The flowers are small, green and fairly inconspicuous.

Fruit, cone, nut, and seed descriptions:

Berry-like fruits are in clusters on female plants only. They are dark blue in late spring and early summer, turn black in August and persist throughout the winter.

Plant care:

This is an invasive plant. It is illegal to sell in Illinois.

However, if the plant is already persisting, there are several management methods.The buckthorn can be managed culturally by pulling small plants and seedlings or mowing them over. Large plants can be girdled by removing 2 inch strips of bark from each stem and applying herbicide to the girdled surface.  The buckthorn can also be controlled chemically in late fall. Systemic chemicals can be sprayed on the plant to be drawn down into the plant’s roots.  Furthermore, a stump treatment can be implemented by using glyphosate or triclopyr paint or spray on a freshly cut stump.

List of pests, diseases, and tolerances:

Buckthorn is susceptible to rust and powdery mildew.  

Buckthorn is on Illinois’ exotic weed list due to its high germination rate in a variety of habitats including gardens, fence rows, pastures, prairies, and abandoned farm fields. In woodlands it can completely replace existing understory plants, including native wildflowers. Seeds remain viable in soil for 2 to 3 years which contributes to the invasive nature of this plant.

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