INVASIVE PLANTS OF OHIO
Fact Sheet 9 - Factsheet in .pdf format
Japanese Honeysuckle & Asian Bittersweet
Lonicera japonica, Celastrus orbiculatus
Both Japanese honeysuckle and Asian bittersweet are non-native, fast-growing trailing or climbing woody vines capable of covering large areas of ground or extending into the tops of trees. Japanese honeysuckle has entire, oval-oblong, opposite leaves from 11/2 -3 inches long.
In Ohio, the leaves are semi-evergreen, persisting late into winter or early spring. The stems are usually hairy and hollow inside, reaching a length of 30 feet or more. A profusion of 2-tipped, very fragrant, white to yellow flowers is produced in pairs in the leaf axils along the stems from April through June. The fruit is a many-seeded, black, pulpy berry maturing from September to November. Native honeysuckle vines (L.dioica) differ in that they bear red fruit at the ends of stems and the upper leaves or the stem are joined together.
Asian bittersweet has finely-toothed, rounded, alternate leaves up to 4 inches long. The stems are round, often with noticeable lenticels, and may reach a length of 60 feet. Asian bittersweet produces numerous 5-petaled, greenish flowers that arise from the leaf axils. The fruit is a conspicuous, yellow, 3-valved capsule that splits open to reveal 3 bright orange-red seeds. The native bittersweet (C. scandens) can be distinguished by its elliptical shaped leaves and its flowers and fruits that arise at the tips of stems.
Both Japanese honeysuckle and Asian bittersweet thrive in disturbed areas such as roadsides, fence rows, abandoned home sites and forest gaps caused by windfalls and logging. Areas of special concern are woodland edges, early successional forests, and riparian corridors. Although preferring sunny areas, both are shade-tolerant and can live in marginal habitats until favorable conditions arise.
Japanese honeysuckle is native to eastern Asia and was introduced into New York in 1806 as an ornamental plant and ground cover. Now distributed over most of the southern and eastern United States, it is often planted as a source of food for wildlife. Asian bittersweet is also native to eastern Asia and was introduced into the United States in 1860 for ornamental purposes, for which it is still used in many areas. Having escaped from cultivation, it can be found over much of the eastern Midwest and Atlantic coast states. Both species are found throughout Ohio but seem to be more prevelant in the southern part of the state.
Japanese honeysuckle and Asian bittersweet are aggressive growers that can severely damage native plant populations by limiting needed sunlight, constricting nutrient flow in stems, and over-weighting treetops increasing the likelihood of wind damage. Both are prolific seed producers with the seeds often being dispersed by birds. The root systems are very persistent and capable of extensive root suckering. Plants tend to regenerate quickly after cutting. These vines are often able to out-compete native species for nutrients and water.
Hand-pulling with complete root removal is effective in small populations of both Japanese honeysuckle and Asian bittersweet. Mowing may also be effective in reducing the size of the plants, but often encourages extensive root suckering. Japanese honeysuckle may be controlled with prescribed burning.
Chemical control of Japanese honeysuckle and Asian bittersweet may be attained using systemic herbicides such as RoundupÂ®, GlyproÂ®, Garlon 3AÂ®, or Garlon 4Â®) on cut stems or as a foliar spray. For foliar applications, the plants should first be cut to the ground and the resprouting foliage sprayed about 1 month later. Foliage of honeysuckle can also be sprayed in the fall or early spring when other species are dormant.
Currently there are no biological controls for Asian bittersweet or Japanese honeysuckle, although animal grazing may control the spread of Japanese honeysuckle.
ADDITIONAL INFORMATION SOURCES:
Bartlow, J., K. Johnson, M. Kertis, T. Remaley, S. Ross, E. Simet, T. Smith, 13. Soehn and G.Taylor. 1996. Invasive Exotic Pest Plants in Tennessee. Tennessee Exotic Pest Plant Council.
Dreyer, G. 1994. Element Stewardship Abstract for Asiatic and Oriental Bittersweet. The Nature Conservancy.
Nuzzo, V. 1997. Element Stewardship Abstract for Japanese Honeysuckle. The Nature Conservancy.
Virginia Native Plant Society. 1995. Invasive Alien Plant Species of Virginia: Oriental Bittersweet (Celastrus orbiculatus).