Japanese Honeysuckle (EwA Guide to Common Invasive Species in Middlesex County (MA, US) )

Japanese Honeysuckle

Lonicera japonica

Summary ⁶

Lonicera japonica, known as Japanese honeysuckle and golden-and-silver honeysuckle, is a species of honeysuckle native to eastern Asia, including many parts of China. It is often grown as an ornamental plant, but has become an invasive species in a number of countries. Japanese honeysuckle is used in traditional Chinese medicine.

Short Description ⁷

A twining vine that spreads by seeds dispersed by birds. The stems are reddish brown to light brown. Opposite, entire margined ovate to oblong-ovate leaves. Young leaves are often deeply toothed. White, very fragrant bi-lobed flowers that turn yellow.

Source: EwA Invasive Pocket Fieldguide | © Earthwise Aware

Description ⁶

Lonicera japonica is a twining vine able to climb up to 10 m (33 ft) high or more in trees, with opposite, simple oval leaves 3–8 cm (1.2–3.1 in) long and 2–3 cm (0.79–1.18 in) broad. When its stems are young, they are slightly red in color and may be fuzzy. Older stems are brown with peeling bark, and are often hollow on the inside.

The flowers are double-tongued, opening white and fading to yellow, and sweetly vanilla scented. The fruit, which is produced in fall, is a black spherical berry 3–4 mm (0.12–0.16 in) diameter containing a few seeds. While the nectar from the flowers can be safely consumed by humans, all other parts of the plant have the potential to be toxic.

Invasiveness ⁸

Japanese honeysuckle has become naturalized in Argentina, Australia, Brazil, Mexico, New Zealand, and much of the US, including Hawaii, as well as a number of Pacific and Caribbean islands. It is classified as a noxious weed in Texas, Illinois, and Virginia, and is banned in Indiana and New Hampshire. It is listed on the New Zealand National Pest Plant Accord as an unwanted organism.

Lonicera japonica was initially brought to the United States from Japan in the early 1900s as an ornamental plant. It is still deliberately planted in the United States for reasons such as erosion control or forage for deer, but has become invasive in many areas. It prefers to invade areas that have been disturbed, such as roadsides or floodplains. It will generally only invade forests when the canopy has been opened by logging or fallen trees, as it grows less vigorously in the shade. Once it has invaded an area, Lonicera japonica grows rapidly and outcompetes native plants for sunlight and nutrients. It proliferates using both sexual and vegetative reproduction, producing seeds that are spread by animals and expanding locally via rhizomes. Eventually, it will form a dense thicket which prevents other plant species from germinating in that area. Due to its suppression of germination in the understory, Lonicera japonica also prevents the regeneration of trees.

Management of invasive Lonicera japonica has been achieved through a variety of means. Small patches can be removed by hand, or using simple digging tools, but all plant parts including roots and rhizomes must be removed to prevent resprouting. Larger patches can be removed through repeated mowing, but application of herbicide is also recommended to prevent regrowth. There has been some study of using controlled burns to remove Lonicera japonica, but the underground portion of the plant is usually able to survive and resprout, limiting the effectiveness of this method. Browsing by herbivores may limit its growth, but is unlikely to fully eliminate it. There is currently no known biological control for Lonicera japonica.

🚧 Control Methods (EwA Content Development in Progress) ⁷

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Sources and Credits

(c) Claire O'Neill, some rights reserved (CC BY-NC), uploaded by Claire O'Neill, https://www.inaturalist.org/observations/50334141
(c) Bill MacIndewar, some rights reserved (CC BY-NC), uploaded by Bill MacIndewar, https://www.inaturalist.org/observations/143894856
(c) Deana Tempest Thomas, some rights reserved (CC BY-NC), uploaded by Deana Tempest Thomas, https://www.inaturalist.org/observations/82626565
(c) kathymcg, some rights reserved (CC BY-NC), uploaded by kathymcg, https://www.inaturalist.org/observations/79666220
(c) Claire O'Neill, some rights reserved (CC BY-NC), uploaded by Claire O'Neill, https://www.inaturalist.org/observations/77392255
(c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Lonicera_japonica
(c) Claire O'Neill, some rights reserved (CC BY-SA)
Adapted by Claire O'Neill from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Lonicera_japonica

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