Buckthorn, An Invasive Species. What It Is and How To Get Rid Of It.
Buckthorn, An Invasive Species. What It Is and How To Get Rid Of It.
Submitted by Bob Breisblatt, Glencoe Sustainability Task Force Member
During autumn, when you arrive home from your daily walk, you may have noticed something odd. You come in the front door and you notice you are tracking into your house a purple stain caused by a berry that has stuck to the bottom of your shoe. It is a rite of autumn in the village because of an unwanted invader, the common buckthorn. Buckthorn, once it has established itself, can take the shape of a large shrub or small tree that can grow to heights of 25 to 30 feet. Its bark is gray to brown. The dark green leaves are shiny. The berries form as individual berries in the clusters in the leaf axis.
Its rapid growth and prolific seed production make the plant an aggressive invader. It prevents native plants and trees from establishing themselves and deprives native animal life of its habitats. It can form dense thickets that shade and displace native understory plants, shrubs and tree seedlings. To view an extremely dense thicket just visit the bus stop on the west side of Green Bay Road by Westley Road, then proceed north on the west side of Green Bay until you reach the start of the fenced Chicago Botanical Gardens (CBG) land cleared of buckthorn by the staff of the CBG. The buckthorn has made as shown below an impenetrable thicket. 
Part of the thicket along the West side of Green Bay Road, North of Wesley Road
The Botanical Garden has cleared the area north of the thicket and the result is open land with native trees growing on it.
This picture shows the end of the Buckthorn thicket and the beginning of the land cleared of buckthorn by the Botanic Gardens.
More of the land cleared of Buckthorn, north of the buckthorn thickets.
The invasive buckthorn was native to Europe and was introduced into the United States in the mid-1800s as an ornamental hedge. Birds and other wildlife eat the berries and disperse the seeds. It is difficult but not impossible to remove. It can regenerate after cutting so a herbicide may be needed to rid the buckthorn completely.
Around the village, many homeowners do not recognize buckthorn as an invasive species and treat it as a bush or hedge allowing it to spread outside their property lines. These are not hedges. In fact, their spread prevents higher-quality bushes, native plants and trees from growing. As a homeowner, one should identify if there is buckthorn growing on your property. If it is, you should remove it and replant the area with noninvasive hedges or native plants. Buckthorn is easy to identify in the fall by its bark as shown in the below pictures, again taken along Green Bay Road:
If it is growing on the parkway in front of your house, work with the Village arborist to have it removed. The Village has categorized buckthorn as a removable tree, and planting replacement trees is not required.
The State of Illinois has recognized the threat buckthorn represents to Illinois and its communities and has amended the Illinois Exotic Weed Act, to treat buckthorn as the danger it is to the public and private lands of the State. The amendment to the Illinois Exotic Weed Act went into effect on January 1, 2023. It reads as follows:
(525 ILCS 10/4) (from Ch. 5, par. 934)
Sec. 4. Control of exotic weeds.
* * * * *
(d) Notwithstanding any other provisions in this Section for
the control of exotic weeds, a municipality may adopt an
ordinance to eradicate common buckthorn (Rhamnus cathartica),
glossy buckthorn (Rhamnus frangula), saw-toothed buckthorn
(Rhamnus arguta), dahurian buckthorn (Rhamnus davurica),
Japanese buckthorn (Rhamnus japonica), and Chinese buckthorn
(Rhamnus utilis) on all public and private property within its
geographic boundaries.
(Source: P.A. 102-840, eff. 1-1-23.) (Emphasis added)
This statute gives municipalities in Illinois the authority to enact a program to eradicate buckthorn on all public and private property. In giving municipalities (including Glencoe) throughout the state such extraordinary power, the State of Illinois has recognized the threat buckthorn presents to our lands both public and private.
As residents, we can act on our own. We can remove buckthorn from our property and replace it with non-evasive hedges and native plants.
The question remains: how does one get rid of buckthorn on their property?
1. Chain saw to cut the largest branches and trunks.
2. Branch cutters to cut the thinner branches.
3. Paint the stump with glyphosate to kill the roots.
Illinois and other states have provided guides for buckthorn management:
Illinois Department of Natural Resources Buckthorn Fact Sheet
Morton Arboretum Information on Buckthorn
Minnesota Department of Natural Recourses Buckthorn Management
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