One of the first steps in managing a buckthorn problem is confirming you're actually looking at buckthorn. It's a common plant in Northeast Illinois, but it can be confused with several native shrubs, and treating the wrong plant is wasted time and money.
Here's how to confidently identify common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus) at any time of year.
Identifying Common Buckthorn (Rhamnus cathartica)
Common buckthorn is the most widespread species in the Chicago area and the one you'll most frequently encounter on residential properties.
The thorn. The most distinctive feature is a sharp thorn at the tip of most branches. This is where the plant gets its name. Native shrubs occasionally have thorns, but the combination of a terminal thorn plus the other features below is a reliable indicator.
The bark. On mature stems, the bark is gray-brown and slightly shaggy. If you scratch the outer bark of a young stem, the inner bark is orange-yellow, which is a strong identifier year-round.
The leaves. Leaves are oval to egg-shaped with finely toothed margins and three to five prominent veins that curve toward the leaf tip. They stay green unusually late in fall.
The berries. Female plants produce clusters of small, round berries that turn from green to black in late summer and persist into fall. They're not edible for humans and have a strong laxative effect on birds (which aids in spreading seeds).
Identifying Glossy Buckthorn (Frangula alnus)
Glossy buckthorn is less common than common buckthorn but often found in wetter areas: stream edges, floodplains, and low-lying areas.
No thorns. Unlike common buckthorn, glossy buckthorn has no thorns.
The bark. The bark has distinctive white lenticels (small horizontal markings) on young stems. Scratching young stems reveals orange inner bark, similar to common buckthorn.
The leaves. Leaves are slightly more elongated than common buckthorn, with very smooth margins (no teeth) and a glossy upper surface. This glossy look is how the plant gets its name.
The berries. Berries ripen from red to black and appear at multiple stages of ripeness on the same branch simultaneously.
Year-Round Identification Tips
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Late fall and winter are the easiest time for identification. Common buckthorn holds its leaves weeks after native trees are bare. Look for green shrubs in an otherwise dormant landscape.
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Early spring is also a good window. Buckthorn leafs out earlier than most native plants, so in April, buckthorn shrubs will be fully leafed out while surrounding native shrubs are still budding.
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Scratch the bark. The orange inner bark is visible year-round and one of the most reliable field identifiers.
When in Doubt
If you're unsure whether a plant on your property is buckthorn or a native shrub, take a few photos of the bark, leaves, and berries and send them our way. We're happy to help with identification before you start any removal work.
Contact us with photos and a description of your property, and we can help confirm what you're dealing with.