Japanese honeysuckle (Lonicera japonica) can outcompete native vegetation in various plant communities including but not limited to prairies, barrens, glades, savannas, and bottomland and upland forests. It can send out lengthy runners, creating a dense mat which can completely cover woody species, making it a serious competitor for light. It can also create competition for resources in the soil, as it has been known to send roots out up to 15 feet horizontally and 3 to 4 feet deep. In forest settings, it can prevent new tree seedlings from growing, threatening future forests, by smothering them out.
Japanese honeysuckle is native to Japan and other areas of eastern Asia. It was introduced to the U.S. in 1806 for ground cover in horticultural settings and became widely established in the eastern U.S. by the early 1900s.
The Illinois Exotic Weed Act lists Japanese honeysuckle as an invasive plant.
Japanese honeysuckle has oppositely arranged ovate leaves which get up to 3 inches long. Leaves typically have a smooth edge or margin, but young plants can have leaves with lobed margins. Leaves are somewhat evergreen, persisting late into the winter. Younger stems are flexible, can be slightly fuzzy, and are rusty to light brown in color while older stems are more brittle and are brown to gray in color. Flowers are tubular and appear in pairs in May and June. The fruit are small black berries which persist into the winter.
For more information, explore Management of Invasive Plants and Pests of Illinois.
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