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Last year we reported on oriental bittersweet (Celastrus orbiculatus), a uniquely noxious invasive woody vine. Today we’re bringing it back for another look, with some ID tips and other details.
Oriental bittersweet is found in many different habitats. To complicate matters, its native cousin, American bittersweet (Celastrus scandens) looks similar to orbiculatus but without its aggressive growth rate and size.
Orbiculatus can grow up a tree to nearly 100 feet, with a “trunk” that may reach a diameter of 5 inches. Its extensive vines smother and strangle by cutting off water and nutrient flow to the tree. In what might be a supreme example of botanical irony, oriental bittersweet has even been observed smothering another invasive plant!
Just Say No
At farmers markets, oriental bittersweet is sometimes seen in holiday decorations or wreaths that may spread seed when it falls off the wreath outside. Most likely it is orbiculatus. If you see it for sale at a farmers market or other location, just say no and gently alert the vendor that they might have an invasive plant for sale.
To do that with confidence you’ll need a few ID tips. According to the USDA:
  • Oriental bittersweet’s fruit and flowers are located in the leaf axils along the length of the stem. American bittersweet has fruit and flowers in terminal clusters.
  • Oriental bittersweet has yellow capsules surrounding the fruit, while those of American bittersweet are orange.
  • The pollen of oriental bittersweet is white while that of American bittersweet is yellow.
  • Oriental bittersweet’s roots are orange.
How to remove oriental bittersweet? Matthaei-Nichols Natural Areas Manager Steve Parrish says that a very judicious application of an herbicide to the just-cut surfaces of a branch can be one of the most effective eradication techniques. Start by pulling or digging up sprouts and seedlings. Mowing may work but most be done regularly, otherwise intermittent mowing may stimulate regrowth. Finally, apply an herbicide only to cut branches as a last resort.
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