Invasive Japanese Honeysuckle

First introduced to North America from east Asia in 1806, Japanese honeysuckle (Lonicera japonica) has proven itself to be an aggressive and persistent non-native invasive species.

In appearance, Japanese honeysuckle is similar to other native and introduced honeysuckle species, with narrow funnel-shaped white to yellowish-white flowers opening to widely curling “lips” and simple, dark green oval leaves arranged in opposite pairs along the stem. However, Japanese honeysuckle can be told from native vine honeysuckles by the last pair of leaves on each stem. In native honeysuckles, these leaves are fused to encircle the stem, but they are separate in Japanese honeysuckle. Unlike Japanese honeysuckle, which is a vine, the other two non-native honeysuckle species commonly found in Pennsylvania, Morrow's honeysuckle (Lonicera morrowii) and Amur honeysuckle (Lonicera maackii), are woody shrubs.

Japanese honeysuckle's seeds are dispersed by birds that eat its fruit, but it also spreads vegetatively. Its stems can take root wherever they contact moist soil and it can climb surrounding vegetation, shading and choking its neighbors to reach better sunlight. Japanese honeysuckle climbs better than native vine honeysuckle species, and is tolerant of the filtered sunlight in mature forests, conditions which limit invasion by most other exotic plants. Japanese honeysuckle also retains its leaves longer into the winter than most native broadleaf plants, which allows it to keep growing after its competition has gone dormant for the season.

Today's photos of Lonicera japonica are: flower by James R. Allison Georgia Dept. of Natural Resources; fruit by Ted Bodner, Southern Weed Science Society; and infestation by Chuck Bargerson, University of Georgia.

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