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Oriental bittersweet (Celastrus orbiculatus)
Woody, perennial, climbing vine. Stems may reach 6” in diameter. Male and female flowers usually borne on separate plants.
Oriental bittersweet is Restricted (Orange counties)
Other names for this plant include:
- Common names: Asian bittersweet, Japanese bittersweet, round leaf bittersweet
- Scientific names: C. orbiculata; C. articulatus
- Invades forests, woodlands, fields, hedge-rows, and coastal areas and can grow in open sites or under closed forest canopy.
- Oriental bittersweet grows rapidly and is tolerant of a wide range of habitats.
- May damage trees by girdling trunks with its woody stem, shading out the tree’s leaves, or weighing down its crown, making it susceptible to damage from wind or heavy snowfall.
- It is widely planted as an ornamental vine, and is sometimes planted accidentally when mistaken for American bittersweet.
Classification in Wisconsin: Restricted
Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for Oriental bittersweet was based upon this literature review developed by the department.
Leaves: Alternate, glossy, and round with a pointing tip and shallow-toothed margins, 2-5” long.
Flowers: Small, inconspicuous, 5-petaled, greenish-yellow flowers in clusters of 3-7 at leaf axils. Most plants dioecious.
Fruits & seeds: Showy, round capsules, clustered in leaf axils. Green in summer, yellow-orange in fall. Split open at maturity to reveal three red-orange, fleshy fruits, each containing 1 or 2 seeds. Dispersed by birds and small mammals.
Roots: Spreading underground roots can sprout to form new stems.
Similar species: American bittersweet (Celastrus scandens; native) has fewer, larger clusters of fruits or flowers, which are terminal rather than at leaf axils. Its leaves are less rounded and nearly twice as long as wide. Hybrids of the two occur, which may make identification difficult.
Counties in WI where Oriental bittersweet has been reported (as of July 2011). Both vouchered and unvouchered reports included.
Do you have Oriental bittersweet in your county but it isn't shaded on the map? Send us a report.
Mechanical: Dig out or hand pull seedlings.
Chemical: Basal bark with triclopyr ester plus a surfactant. Cut stem treatment with glyphosate or triclopyr amine. Foliar spray with triclopyr ester or triclopyr amine plus a non-ionic surfactant.
View Oriental bittersweet pictures in our photo gallery!
Sources for content:
- Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. University of Wisconsin Press. 2005. Pg. 45-46
- Swearingen, Jil M. Plant Conservation Alliance, Alien Plant Working Group. Least Wanted: Oriental bittersweet. Last updated June 2006.
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