Family: Honeysuckle Family (Caprifoliaceae)
Origin and Distribution: Japanese honeysuckle was introduced into New York from East Asia in 1806 as an ornamental. The first report that it escaped from cultivation did not appear until 1898 after which it quickly spread throughout the eastern U.S. It now occurs most abundantly in an area extending north to Long Island, west to central Illinois, and south to Florida. Japanese honeysuckle is naturalized throughout Ohio with the exception of a few northwestern counties. The plant is frequently found growing beside roads, railroads, fences, fields, and woods. Japanese honeysuckle is an invasive plant when growing on fertile soils in full sun. It grows less vigorously on poor soils or in shade.
Plant Description: Japanese honeysuckle is a twining woody vine. Unlike native honeysuckles, this introduced species grows so rapidly that it overwhelms and literally smothers other plants. Identifying features include woody vines that trail or climb by twining around objects (other vines climb by way of tendrils, adhesive discs, or aerial roots), yellowish flowers located in pairs at leaf axils, opposite leaves that are separated rather than joined at the base as in other honeysuckle vines, and small black berries. The plant reproduces by seeds and creeping, above-ground stems that can root at the nodes and develop into new plants.
- Root system - The root system is extensive and may be over 10 feet across and 3 feet deep.
- Stems - Vines grow vertically by climbing and horizontally along the soil surface. Young stems are green and finely hairy while older stems are woody, hollow, and have brown bark that may peel off in shreds. Creeping above-ground stems can grow 30 feet or more in a year.
- Leaves - Leaves are opposite (2 leaves per node), 3 inches long, egg-shaped, hairy, and smooth-edged. Leaves are semi-evergreen, so they persist in the south. During mild winters in the north, plants shed leaves late in the season and new leaves appear early in spring.
- Flowers - The 2-lipped flowers are comprised of 5 petals united into a 1- to 2-inch-long tube. When young, flowers are white tinged with purple or pink and they become yellowish with age. Flowers form in pairs on short stalks arising from the leaf axils of young branches.
- Fruits & Seeds - Fruit is a black, shiny, firm berry containing several seeds that are dark gray-brown and less than 1/8 inch long. One side of each seed is 3-ridged while the other is either flat or concave.
Similar Species: Trumpet honeysuckle (Lonicera sempervirens) and wild honeysuckle (L. dioica) are native honeysuckles that grow as vines so they could be confused with Japanese honeysuckle except their uppermost pairs of leaves fuse together at the base forming a double-leaf and their berries are red to orange. Amur honeysuckle (L. maackii), belle honeysuckle (L. bella), Morrow's honeysuckle (L. morrowi), and tatarian honeysuckle (L. tatarica) are difficult to separate from each other, but their shrub-like growth habit makes them easy to distinguish from Japanese honeysuckle.
Biology: Japanese honeysuckle flowers are produced from April until July and fruits ripen in September to November. Some people plant the vine in their gardens for the ornamental value of its fragrant flowers and fast-growing vines. It is also used as ground cover for soil erosion control and to provide food and shelter for wildlife. Birds eat the berries sparingly and then disseminate the seeds and the semi-evergreen foliage is a primary source of winter forage for white-tailed deer. Regardless of possible benefits, Japanese honeysuckle remains a potentially serious pest because of its tendency to strangle out native species. The plant can be controlled by foliar applications of herbicides in late fall after frost when other deciduous species have dropped their leaves. Japanese honeysuckle does not survive repeated cultivation and it generally fails to establish or is less invasive under shaded conditions such as beneath a grass or forest canopy. Pulling, cutting, mowing, or burning generally leave roots that sprout producing dense re-growth.
Toxicity: Ingestion of the berries in large quantities is reported to cause sickness that may lead to a coma.
Facts and Folklore:
- The flowers are used in China as a folk remedy for snakebites.