September’s Weed of the Month, Oriental bittersweet (Celastrus orbiculatus), is a woody vine with colorful red fruit. It was brought to North America from Asia and used as an ornamental plant. The attractive vines have been used for wreath decorations and in floral decorations; unfortunately, the plant has escaped cultivation and has become invasive in residential and natural areas in Minnesota.
Oriental bittersweet spreads by several means. The persistent red fruit is consumed by birds, which spread the seed to uninfested areas. People trained to look for Oriental bittersweet may look for places where birds perch. The areas beneath the perches may have Oriental bittersweet seedlings, juvenile vines, or mature woody vines and would be a place to target control efforts. Humans also spread Oriental bittersweet infestations by physically moving the plants. Oriental bittersweet was commonly propagated and sold in Minnesota through nurseries and retail garden centers before 2010. Its use in floral arrangements and wreaths also increased its spread.
Despite its ornamental characteristics, Oriental bittersweet is an ecological threat to forests, grasslands, and parks in Minnesota. The vines twine around trees, girdling them in a snake-like fashion. Though it prefers forest edges and sunlight, Oriental bittersweet can grow in forest understories, eventually reaching forest canopies, shading the trees and understory and preventing native plant species from flourishing. Infestations can become so thick that wildlife, such as deer, can have difficulty navigating through wooded areas filled with Oriental bittersweet.
Oriental bittersweet has identification characteristics to help distinguish it from other woody vines. The mature fruit is a red berry with a yellow capsule. The berries are attached along the stem where the leaves meet the stem. This should not be confused by American bittersweet which has red berries with orange capsules. Additionally, dense infestations of Oriental bittersweet will give a wooded area a messy, chaotic look.
As a target weed on Minnesota’s Noxious Weed Eradicate List, it’s required by law that all above- and below-ground plant parts must be destroyed. Recommended management practices for Oriental bittersweet include the following:
To report infestations of Oriental bittersweet or any other noxious weeds on the eradicate list, please notify MDA by email at firstname.lastname@example.org , or voicemail at 1-888-545-6684 (toll-free).
See the Oriental bittersweet webpage for more detailed information.