Invasive Species

The spread of invasive species is a major factor contributing to ecosystem change and instability throughout Chicagoland. Invasive species displace or wipe out native species, damage infrastructure, and threaten human livelihoods.

In Lake County, the invasive species common, or European, buckthorn (Rhamnus cathartica) is of particular concern. Buckthorn accounts for 52.2% of the county’s trees. We aim to eliminate buckthorn from all forest preserves and reduce it by 50% countywide by reaching out to private landowners, working with Lake County schools, and teaming up with partners.

The Buckthorn Stops Here

Join The Movement

TEDx VernonAreaLibrary

Former Public Affairs Manager Allison Frederick describes how to join forces and stop buckthorn in our own yards. This talk was given at a TEDx event using the TED conference format but independently organized by a local community.

Learn More in our Horizons Magazine

Identify Buckthorn

Fall is a good time to identify buckthorn and plan for removal efforts over the winter. Manager of Restoration Ecology Matt Ueltzen shares tips on buckthorn identification, buckthorn berries, and a simple strategy to get started with buckthorn removal.


One buckthorn identification tip is to look for plants that are still green well into November. Even as native oak, hickory, maple and other types of trees are changing color and dropping their leaves, buckthorn holds on to its green leaves for quite a while past that point. In late fall, look for a dense thicket of green vegetation shorter than the canopy trees above. Many of these plants are likely buckthorn.


Look for quarter-inch, glossy, black-purple berries or fruits ripening from September through November. Buckthorn is a dioecious species, which means male and female plants are separate. Only female plants produce berries, which contain three to four seeds each and have a laxative effect on birds that eat them. We recommend removing female plants first, since they produce the berries that keep buckthorn populations going and growing.


Buckthorn has oval- or egg-shaped, shiny, small-toothed leaves with prominent veins and a pointed tip. They grow in a subopposite pattern. When you look at a branch, the leaves and twigs on either side of it grow both directly opposite and alternate from one another.


Also look at buckthorn bark. On the outside, young stems have gray-brown bark with small, horizontal, white-gray dots called lenticels. As plants age, the bark turns a dark charcoal gray-to-black color. The lenticels grow and split, as well, causing a flaky appearance. If you cut into a buckthorn plant, the interior of the bark is a distinctive orange color, not found in any other woody plant in Lake County.


Once you’re confident you have buckthorn on your property, mark the plants you want to remove over the winter. You may want to tie small, colored ribbons around branches or stems, place pin flags at the bases of the plants or apply spray paint to branches or stems.

Remove Buckthorn

Matt Ueltzen, manager of restoration ecology, and Stewardship Ecologist Kelly Schultz share tips on how to remove buckthorn safely and effectively from a home landscape.

Herbicide Tips and Tricks

Learn important tips and procedures to properly obtain and apply herbicide during efforts to remove buckthorn and other invasive species.

Buckthorn Herbicide Guide

Native Landscaping Resources

Ready to get started with native landscaping and invasive species removal and replacement? Visit our digital resources hub and join the Healthy Hedges movement.

Native Plant Resources

Before and After Buckthorn Removal´╗┐

Use the arrows below to view three areas in the preserves before and after buckthorn removal. The difference is significant!


A New Fall Fashion

Environmental Communications Specialist Brett Peto shares how you can help make buckthorn eradication a new fall fashion in our Lake County Nature blog archive.

Learn More on our Blog

Buckthorn Removal in Progress Sign

Are you in the process of removing buckthorn from your property, but not quite buckthorn-free? Download, print and display this “Buckthorn Removal in Progress” sign to let your neighbors know you care about the health of plants, animals—and people!

Buckthorn Removal in Progress Sign

Buckthorn-Free Garden Flags

Native gardens are something to see. Is your property buckthorn-free? Do you live in Lake County, Illinois? Are you proud of the ecological health of your yard and garden?

If you answered yes, apply below to receive a FREE commemorative garden flag set. 

Garden flag sets are supported by a grant from the Preservation Foundation of the Lake County Forest Preserves.

Buckthorn-Free Flag Details

The 12.5”x18” flag is made of durable vinyl resistant to fading in the sun and features original watercolors of native plants by Forest Preserves staff. The accompanying metal stand is three feet tall, made of powder-coated iron and comes in one piece—no assembly required! Two rubber stoppers and one anti-wind clip are also included.


Buckthorn-Free Qualification

To qualify for a flag set, you must upload two to six photos of your property demonstrating that it is free of invasive buckthorn. One flag set per property. Qualified landowners may pick up their flag set at our General Offices, 1899 W. Winchester Road, Libertyville, IL 60048.

Buckthorn-Free Application Form

If you are unable to fill out the form or have questions, please call 847-367-6640 or email

Buckthorn Eradication Pilot Project

In 2015, we began a pilot project to eradicate buckthorn in a 2,900-acre landscape surrounding Middlefork Savanna in Lake Forest. Bounded by I-94 and Routes 176, 43 and 60, this area contains the 687-acre preserve and about 700 public and private properties. We are working to include these landowners in a large-scale push to eradicate buckthorn locally, called the Buckthorn Eradication Pilot Project.

A 50/50 cost-share program, supported by a grant from the National Fish and Wildlife Foundation Chi-Cal Rivers Fund, is available to assist landowners in the project area with removing buckthorn and replacing it with beneficial native plants. Please fill out the contact form to inquire about grant funds for your property.

Learn More in our Horizons Magazine

Frequently Asked Questions

I understand the ecological impacts of buckthorn, but it offers privacy screening. What can I do to preserve privacy?

This is a common perspective. For many people, their yards are a reflection of who they are and an important part of what makes their property feel like home. The good news is buckthorn removal can be completed over time; it doesn’t have to be an overnight project. Additionally, native shrubs and trees can provide privacy screening once they are established in your yard. You can remove invasive species like buckthorn and still preserve the aesthetics of your home.

I heard buckthorn is actually good for animals. Is that true?

Unfortunately, this is inaccurate. Buckthorn can be quite harmful to many animals that live on or near your property. For example, its fruits offer little nutritional value for wildlife and have a diuretic effect on birds, which often spread buckthorn seeds across property lines.

Isn’t it bad to remove trees, even if they are buckthorn?

While removing trees can feel counterintuitive, buckthorn is uniquely suited to outcompete many species that are native to our region, which severely degrades the overall health of local ecosystems. Entire woodlands, habitats and even yards can become infested with buckthorn overgrowth. This can choke out the next generations of native plants, particularly oaks. Removing buckthorn and replacing it with native plants is beneficial to the local landscape.

What are some of the alternative plants available?

There are great alternative, low-maintenance, native plants you can plant in your yard. Consider native plants such as wild plum (Prunus americana), any native species of hawthorn (Crataegus spp.), American hazelnut (Corylus americana), wild black currant (Ribes americanum), witch hazel (Hamamelis virginiana) and butterfly weed (Asclepias tuberosa). See more recommendations on our Native Plants and Healthy Hedges webpage.

What is the Lake County Forest Preserves’ role in buckthorn removal?

As principal guardian of Lake County’s open space and natural areas since 1958, we are focused on preservation, restoration, education and recreation. The reality is that buckthorn does not observe property boundaries. To most effectively tackle the issue, we want to encourage private landowners to remove buckthorn from their properties and communities as we remove it from the preserves.

Contact Us

Need help with invasive species removal and replacement or another landscaping issue? Please fill out the contact form below. If you are unable to fill out the form or prefer to inquire another way, please call 847-367-6640 or email



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