Oriental Bittersweet (Celastrus orbiculatus Thunb.)
September 18, 2007
Synonym: Asian bittersweet
History and use. Introduced from Asia in 1736. Very showy ornamental with berried vines that are traditionally collected as home decorations in winter.
Resembles American bittersweet, C. scandens L., which has only terminal flowers and fruit, and leaves usually twice as large but absent among the flowers and fruit. Hybridization suspected between the two species.
Also resembles grape vines, Vitis spp., in winter, but can be distinguished by persistent scarlet fruit versus grapes.
Ecology. Occurs on a wide range of sites mainly along forest edges. Found as scattered plants to extensive infestations in forest openings, margins, and roadsides as well as in meadows. Mostly shade intolerant. Colonizes by prolific vine growth and seedlings, and spreads by bird- and other animal-dispersed seeds and humans collecting decorative fruit-bearing vines.
Plant. Deciduous, twining and climbing woody vine to 60 feet in tree crowns, forming thicket and arbor infestations. Elliptic to rounded leaves, dangling clusters of inconspicuous yellowish flowers in spring, and green spherical fruit that split to reveal three-parted showy scarlet berries in winter.
Stem. Woody vine to 4 inches diameter, twining and arbor forming, with many alternate drooping branches growing at angles and eventually becoming straight. Olive drab with many raised whitish corky dots (lenticels) becoming tan to gray. Branch scars of fruit clusters semicircular, each with a tiny corky shelf projection.
Leaves. Alternate, 1.2 to 5 inches long. Variable shaped, long tapering tipped when young becoming larger and round tipped when mature. Margins finely blunt toothed. Dark green becoming bright yellow in late summer to fall. Base tapering into 0.4- to 1.2-inch petiole.
Flowers. May. Numerous tiny-branched axillary clusters (cymes), each with three to seven inconspicuous orange-yellow flowers. Five petals. Fruit and seeds. August to January. Dangling clusters of spherical 0.5-inch capsules, tipped with a persistent pistil. Green turning yellow orange then tan. In winter, splitting and folding upward to reveal three fleshy scarlet sections, each containing two white seeds. Persistent in winter at most leaf axils.
Recommended control procedures:
Thoroughly wet all leaves with one of the following herbicides in water with a surfactant (July to October): Garlon 4, Garlon 3A, or a glyphosate herbicide as a 2-percent solution (8 ounces per 3-gallon mix). For stems too tall for foliar sprays, apply Garlon 4 as a 20-percent solution in commercially available basal oil, diesel fuel, or kerosene (2.5 quarts per 3-gallon mix) with a penetrant (check with herbicide distributor) to the lower 16 inches of stems. Or, cut large stems and immediately treat the cut surfaces with one of the following herbicides in water with a surfactant: Garlon 4 or a glyphosate herbicide as a 25-percent solution (32 ounces per 1-gallon mix).
From: Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.
Oriental bittersweet: a patient invader. (Research news release.) http://www.srs.fs.usda.gov/news/63