Bill Johnson

Japanese Honeysuckle

Lonicera japonica Thunb.
Honeysuckle family (Caprifoliaceae)

Origin: Eastern Asia

Background
Japanese honeysuckle was introduced to Long Island, New York, in 1806 for ornamental, erosion control and wildlife uses.

Distribution and Habitat
Japanese honeysuckle is one of the most recognizable and well established ornamental vines in the U.S. It is documented to occur and reported to be invasive throughout the eastern U.S. from Maine to Florida and west to Wisconsin and Texas, with scattered occurrences in the Southwest. It is adapted to a wide variety of habitats from full sun to shade.

Ecological Threat
It is a fast-growing vine that twines around stems of shrubs, herbaceous plants and other vertical supports. In full sun it forms large tangles that smother and kill vegetation. It can kill shrubs and saplings by girdling.

Description and Biology

• Plant: perennial, deciduous to semi-evergreen twining vine; stems are pubescent and reddish brown to light brown.
• Leaves: paired (opposite), ovate to oblong-ovate, about 1-3 in. long by ½-1½ in. wide, entire-margined except for young leaves which are often deeply toothed.
• Flowers, fruits and seeds: flowers are bi-lobed, white turning yellow, highly fragrant and with nectar, produced in June; fruits are black, about ¼ in. diameter, paired, produced in the fall.
• Spreads: by seed that is dispersed by birds.
• Look-alikes: native trumpet honeysuckle which has red or yellow, long tubular flowers.

Prevention and Control
Small infestations can be controlled by hand removal of vines. Large infestations require mowing twice or more per year or treatment with systemic herbicides like those containing glyphosate or triclopyr (see Control Options). No biological controls are available.

Native Alternatives
Coral honeysuckle (Lonicera sempervirens), hairy honeysuckle (L. hirsuta), crossvine (Bignonia capreolata) and trumpet creeper (Campsis radicans).