Oriental bittersweet leaves and fruits

Oriental bittersweet, Asian bittersweet (Celastrus orbiculatus, Celastrus loeseneri)

Perennial, woody climbing vine. Prolific producer of red-orange berries. Stems may reach 6” in diameter. Male and female flowers usually borne on separate plants.

Overview

Regulated areas of Oriental bittersweet
Oriental bittersweet (C. orbiculatus) is Restricted (Orange counties)

Asian bittersweet (C. loeseneri) is Proposed as Prohibited

Other names for this plant include:

  • Common names: Asian bittersweet, Asian loeseneri bittersweet, Japanese bittersweet, round leaf bittersweet
  • Scientific names: Celastrus rosthornianus var. loeseneri, C. orbiculata; C. articulatus

Ecological threat:

  • 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, Prohibited

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. The recommendation for Asian bittersweet was based upon this literature review developed by the department.

Identification

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.

Distribution

Known county distribution of Oriental bittersweet
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.

Control

Mechanical:

  • Dig out or hand pull seedlings.
  • Cut the base of the vines strangling trees, allowing upper foliage to die back.

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.

For more information on control techniques, visit the bittersweet factsheet [exit DNR] by University of Wisconsin-Extension.

Photos

View Oriental bittersweet pictures in our photo gallery!

Resources

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 [exit DNR]. Last updated June 2006.

Links for More Information

Last revised: Tuesday October 22 2013