Texas Invasive Species InstituteCelastrus orbiculatus
Oriental Bittersweet
Class: Magnoliopsida
Order: Celastrales
Family: Celastraceae
Photographer: James H. Miller Photographer: James R. Allison
Source: USDA Forest Service, Bugwood.org Source: Georgia Dept. of Natural Resources
Description: Celastus orbiculatus is a woody perennial plant that grows as a climbing vine or ground shrub. Leaves are alternate, round with finely toothed margins and glossy. There are separate plants with female plants being the ones that bear fruit (pictured right) and male plants are non-fruiting. Besides fruiting the male and female plants also have different morphologies with female plants producing clusters of small greenish flowers in axillary clusters. The abundance of red and orange fruits allows this plant to proliferate quickly and has also made Oriental bittersweet extremely popular in flower arrangements.
Ecological Threat: Oriental bittersweet is a vigorously growing vine that climbs over and smothers vegetation because it deprives the plant from sunlight, preventing photosynthesis. When bittersweet climbs high up on trees it adds weight which can then lead to uprooting and blow-over during high winds and heavy snowfalls. Also, Celastus orbiculatus is displacing our native American bittersweet (C. scandens) through competition and hybridization.
Biology: This vine produces many seeds that are dispersed into new areas by small mammals, and birds including, mockingbirds, blue jays and European starlings. Since the seeds can be dispersed by birds this allows the plant to spread quickly and over long distances. The seeds germinate in late spring; but the vine can expand vegetatively through rootsuckers.
History: Since Celastrus orbiculatus has eye-catching fruit it was imported from Asia as an ornamental for gardens and florists in 1860. Naturalized plants were fist collected in Connecticut in 1916. Now the plant has become naturalized in 21 of the 33 states it is present in.
U.S. Habitat: Forests, woodlands, fields, coastal areas and salt marsh edges; usually those lands that have been disturbed.
Distribution
Native Origin: Eastern Asia, Korea, China and Japan
U.S. Present: AR, CT, DC, DE, GA, IA, IL, IN, KY, MA, MD, ME, MI, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WI and WV
Resembles/ Alternatives
Oriental bittersweet can be confused with the American bittersweet (C. scandens). However, American bittersweet has fewer and larger clusters of fruits whereas Oriental bittersweet is a prolific fruiter with lots and lots of fruit clusters emerging at many points along the stem. Additionally, American bittersweet has terminal flower clusters while Oriental bittersweet have auxiliary flower clusters. Unfortunately, hybrids of the two occur which may make identification more difficult.
Management
Celastrus orbiculatus can be treated by herbicides including Glyphosate and Triclopyr. It can be applied to cut stems or to the leaves. Sometimes on new stems a foliar application may be needed later. The ideal time to spray is after surrounding native vegetation has become dormant (October- November) to avoid affect them.
Text References
Clement C.; Warren, R.; Dreyer, G.; Barnes, P. 1991. Photosynthesis, water relations and fecundity in the woody vines American and Oriental bittersweet (Celastrus scandens and C. orbiculatus). Annual Meeting Botanical Society of America. Journal of Botany 78 (6 suppl.): 134-135.
Dreyer, G. 1988. Efficacy of triclopyr in root-killing Oriental bittersweet and certain other woody weeds. Proceedings of the Northeastern Weed Science Society Vol. 42:120-121.
Hutchison, M. 1992. Vegetation management guideline: round-leaved bittersweet (Celastrus orbiculatus Thunb.). Natural Areas Journal 12(3):161.
Wheeler, L. 1987. Oriental bittersweet: avian dispersal in winter in relation to other species of fruiting plants. Undergraduate Individual Study Report, Zoology Department, Connecticut College, Unpublished.
Internet Sources
http://plants.usda.gov/core/profile?symbol=CEOR7
http://invasive.org/browse/subinfo.cfm?sub=3012
http://www.nps.gov/plants/alien/fact/ceor1.htm
http://www.invasive.org/weedus/subject.html?sub=3012.
