Fall colors are fading away, but the bright orange-red fruits of bittersweet vines remain. Beware of impostors though, as the highly invasive oriental bittersweet (Celastrus orbiculatus) can look a lot like our native American bittersweet (Celastrus scandens). Mistaking these two plants could have grim consequences, as oriental bittersweet overruns forest understories and strangles native trees.
Once oriental bittersweet makes its way into a forest, no tree is safe. Growing as a vine to nearly 100 feet in length and 7 inches in diameter, this nasty invasive species can kill or break trees in several ways. By coiling itself around tree stems, it can strangle trees, cutting off the flow of water and nutrients. If that doesn’t finish the tree off, oriental bittersweet’s foliage can overtop and shade out trees, weakening them to other stressors. All this extra weight also increases the risk of branch or stem breakages during snow, ice, and wind storms. Plants on the forest floor or in open fields are at just as much risk, as dense mats of low-growing oriental bittersweet block out the light to shrubs, grasses, and wildflowers.
Now might seem like a good time to start chopping away at any vines with red berries, but don’t forget about American bittersweet. Fortunately, identification is simple, even when the leaves fall off – just look for the fruits! American bittersweet fruits are clustered at the tips of stems, while oriental bittersweet fruits are spread out along the stems. Another thing to look for are the capsules that cover the red fruits. Capsules are orange on American bittersweet and yellow on oriental bittersweet.
Take a look at the best control practices guide from the Michigan Department of Natural Resources.
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