Oriental Bittersweet
Do we need another invasive plant pest?
No, but we have one invading our parks and woods. It’s called Oriental Bittersweet (Celastrus orbiculatus). It has lovely berries and, as seems to be the case so often, was viewed as a nice ornamental plant to have in the landscape. Like Common Buckthorn, those berries are super spreaders. The plant can grow 15 feet per year and reach stem thickness of 5 inches. As it climbs trees in search of light, it girdles the tree and eventually smoothers it. In 2015 Jim Proctor of the Friends Invasive Plant Action Group reported finding it in Wirth Park near the Garden. It is now known in a number of Hennepin County Parks - but there is still a chance to eliminate it unlike Buckthorn which can only be controlled.
The plant was brought into North America in the late 19th Century. It is now endemic and out of control in a number of eastern states. The University of Minnesota Plant Checklist states it was first collected in Minnesota in 2002 in a Hennepin County Park. The Minnesota DNR plant survey from 2019 reports it in Anoka, Hennepin and Ramsay Counties. The EDDMapS site reports more counties but until the DNR confirms that, it could be a case of mistaken identity.
Here is the current distribution map posted by EDDMapS.
So - how do you distinguish it from our native American Climbing Bittersweet (Celastrus scandens)?
This quick chart from the Minnesota Department of Agriculture gives the basics. Then refer to this comprehensive key from the USGS.
Oriental Bittersweet was classified as a noxious weed in Minnesota in 2011. Volunteers can help find and mark this plant for eradication. Winter is the best time when the fruits can be identified. Three Rivers Park Districtruns such a program. Findings can also reported directly to the Minensota DNR at "Report a Pest" and also individuals can log it on the EDDMapS site.