Japanese Honeysuckle (Lonicera japonica)
Japanese honeysuckle (Lonicera japonica) is a semi-evergreen, woody, trailing or climbing vine native to Eastern Asia. Introduced to Long Island, New York in 1806, Japanese honeysuckle has been used for a variety of purposes, including as an ornamental for its beautiful and fragrant flowers, planting along highways for erosion control, and even by wildlife managers as winter forage for deer. Despite its many uses, Lonicera japonica has the ability to spread quickly choking out native vegetation in the process; it is considered an invasive pest because of these characteristics. Japanese honeysuckle invades a wide variety of habitat types, from the forest floor to the canopy, roadsides, wetlands, and areas where the native vegetation has been disturbed. Lonicera japonica is in the SLELO PRISM and is on the General Species of Concern List.
Lonicera japonica crowds out native species. It outcompetes them both for light (shoot competition) and below-ground resources (root competition). Japanese honeysuckle will grow during part, if not the entire, winter when many native species are dormant. Because it can be either a trailing or climbing vine, Japanese honeysuckle is able to grow by twining up other more established plants ultimately suffocating them. If its density of growth is high enough, Lonicera japonica can even topple trees and shrubs purely from the weight of its biomass. Due to the ability of Lonicera japonica to create large mono-cultural stands, this species can open the door for other invasive species to become established and thereby further reduce native biodiversity when present.
Japanese honeysuckle prefers partial sun, moist to dry conditions and fertile loamy soil. It is common in southern states as well as, northern Washington state and northeastern US.
Leaves: Japanese honeysuckles possess oval, pubescent (hairy) leaves that are 1-3 inches in length, in an opposite leaf arrangement. The margins are normally smooth, but young leaves may be lobed or toothed.
Stems: Lonicera japonica has a woody stem. Young stems may be pubescent, while older stems are always glabrous (smooth).
Flowers: Japanese honeysuckle flowers between April and July. The whitish-pink flowers are very fragrant, tubular in shape, and turn a creamy-yellow with age. This plant is named after the nectar produced by its flowers, which is sweet tasting and can be suckled from the plant when flowering.
Mechanical: Hand-pulling, grubbing with a hoe or shovel, and removal of trailing vines is practical for small infestations. Pulled plant matter should be removed and destroyed after to prevent rooting and reinfestation.
Fire: In fire-dependent natural communities, prescribed burns are capable of curbing Japanese honeysuckle growth and spread. Although above-ground vegetation is susceptible to fire management techniques, roots and shoots may survive and resprout.
Chemical: Because of its evergreen/semi-evergreen nature, application of herbicides on Japanese honeysuckle is possible when many native species are dormant. A foliar application of 1.5-3% glyphosate or 3-5% triclopyr shortly after the first frost. Monitoring is necessary to determine if a second herbicide application is required.
Title photo and plant identification photos: Victoria Nuzzo, Global Invasive Species Team, The Nature Conservancy. Habitat/Distribution map: USDA Plants Database.
Bravo, Melissa A. “Japanese Honeysuckle.” Plant Conservation Alliance. National Park Service, n.d. Web. <http://www.nps.gov/plants/alien/fact/loja1.htm>.
MacDonald, Greg, Brent Sellers, Ken Langeland, Tina Duperron-Bond, and Eileen Ketterer-Guest. “Japanese Honeysuckle.” Center for Aquatic and Invasive Plants. University of Florida, n.d. Web. <http://plants.ifas.ufl.edu/node/239>.
Nuzzo, Victoria. “Lonicera Japonica.” Bugwood Wiki. Center for Invasive Species and Ecosystem Health at the University of Georgia, n.d. Web. <http://wiki.bugwood.org/Lonicera_japonica>.