Japanese Honeysuckle

Lonicera japonica

Kindgom: Plantae
Phylum: Angiosperms
Class: Eudicots
Order: Dipsacales
Family: Caprifoliaceae
Genus: Lonicera
Species: L. japonica

All in the Family
The Caprifoliaceae or "Honeysuckle" Family is comprised of 800 species. They are mostly ornamental shrubs and vines. Their leaves are either evergreen or decidiuous. The Honeysuckle family has flowers that are tubular bell- shaped with five outward spreading lobes per flower. The fruit is usually a berry or a drupe.

Specifically, the Japanese Honeysuckle has evergreen leaves and berry fruits. The genus Lonicera is comprised of 180 species of arching shrubs and twining vine. Japanese Honeysuckle is a twining vine, which means its stems wrap around a structure. The genus Lonicera was named after Adam Lonicer, a Renaissance botanist from Germany.
Adam Lonicer (1528- 1586)

The Invasion
Japanese Honeysuckle is native to the continent of Asia, specifically the countries of Japan and Korea. In 1806, the plant was introduced to Long Island, New York for the purpose of erosion control and wildlife forage control. Japananese Honeysuckle was chosen because it is an ornamental plant. Not only is it aesthetically pleasing to the eye, the plant smells of a sweet aroma that enticed small children to sample a drop of the honey- flavored nectar.

Although once adored for its beautiful appearance and smell, Japanese Honeysuckle is now seen as an invasive species. The vine- like plant has certain physiological tolerances that allows it to thrive in many types of habitats such as fields, forests, wetlands, barrens, and disturbed lands. 200 years after its introduction, Japanese Honeysuckle is found in 29 states from Texas to the Great Lakes Region to New England. Smaller populations have even been found in Hawaii. Fortunately, severe winter temperatures and low precipitation protect northern latitudes in the West from invasions. Japanese Honeysuckle is considered as a noxious weed in Texas, Illinois, Virginia, and banned in New Hampshire. According to the Invasive Plant Species Assessment Working Group (IPSAWG), Japanese Honeysuckle is most common in Indiana because this state has a lot of naturalized woodland edge zones where this plant typically grows.

Distribution of Japanese Honeysuckle in the U.S

Friend or Foe?
Unfortunately, Japanese Honeysuckle is a friend in Asia but a foe in the U.S. This is because the vine has natural enemies in Asia that helps control its growth, whereas the plant has few known predators in the U.S. These predators include deer, rabbits, and hummingbirds.

Because of this, Japanese Honeysuckle has been able to spread widely and harnesses the ability to outcompete native plants for several reasons. First, it is a psuedo- evergreen, it never loses its leaves and thus maintains its canopy throughout the winter. Secondly, the vines girdle and twist tightly around stems, trunks, shrubs, and young trees which cuts off the flow of water through the plant system. Thirdly, Japanese Honeysuckle grows over vegetation and shields it from sunlight. This prevents vegetation for absorbing its necessary amount of light energy, and consequently the vegetation is unable to photosynthesize and produce sugars. Finally, Japanese honeysuckle outcompetes native plants by engaging in aggressive root competition with neighboring vegetation for the nutrients and minerals in the soil.
Japanese Honeysuckle girdling a red maple sapling. (photo cred Thomas Scheitlin)

Identifying the Foe

The Japanese Honeysuckle is a perennial vine that will return year to year. The vine prefers to grow on a medium with vertical structures such as limbs, trunks, shrubs, and small trees. It will climb by twisting its stems. The vine's leaves occur in pairs along the stem and are oblong to oval in shape. Soft hairs cover the stems and leaves..In southern and mid- Atlantic status, the vine is evergreen and color and its leaves remain attached throughout the winter season. In northern regions, the cold causes the leaves to fall after prolonged exposure to winter temperatures. The Japanese Honeysuckle has flowers that are tubular in shape and white or pink in color, yellow when aged. They are of the eudicot class and have five fused petals that give off a sweet vanilla scent. Flowers appear in pairs along the steam at leaf junctures. Japanese Honeysuckle grows in the spring and blooms in the spring and summer. In the autumn, dark blue globose berry fruits are produced which contain 2-3 oval to oblong, dark brown seeds about 1/4 inch in size.

Flower -------------------------------------------------------------------------------------------------------- Fruit

How it Spreads

This perennial vine is able to grow and spread through two mechanisms: (1) vegetative plant growth and (2) sexual seed dispersal. Long vegetative runners develop roots where steam and leaf junctions touch the moist soil. Rhizomes, the symbiotic partner of the vine's root system, helps to establish and spread the plant locally. Rhizomes fix nitrogen from the atmosphere into a form that the plant can use to form proteins and nucleic acids. In terms of seed dispersal, birds and other wildlife cosume the fruits and defecate the seeds at various locations near the parent plant. In order to stop the growth and spread of Japanese Honeysuckle, several methods have been identified including chemical and non- chimcal options.
Landscape Horticulture at Auburn University

Non- Chemical Management

The management option depends on the size of the infestation and how many people can offer their labor. For small infestations, repeated pulling of entire vines and root systems can be effective. Hold low onto the stem and remove the whole plant including roots when the soil is still moist. To maintain, cut and remove twining vines to prevent them from girdling other plants. Besides manual labor, rake the mass of vines covering the ground and use a chain saw operator to cut the stems low to the ground. Mowing can also be helpful if you mow twice a year, first in mid- July and again in mid- September. Digging tools such as a pulaski can also remove Japanese Honeysuckle, but it is not all that effective. In some situations, tethered goats have been used, but the goats must be watched or they will escape and create another ecological threat.
Volunteer swinging a pulaski, digging tool

Chemical Management

The best time to apply herbicides is during the autumn when other native species are dormant, but the Japanese Honeysuckle is still continuing to photosythesize. The vine needs to have healthy green leaves in order for the herbicide to be effective. Systemic herbicide, such as glyphosate and triclopyr, move through the leaves and stems to the roots. Herbicides vary in application methods so make sure you read the label guidelines.

Alternative Plants
Gelsemium sempervirens, False jasmine
Campsis radicans, Trumpet creeper
Bignonia capreolata, Crossvine
Wisteria frutescens, Native Wisteria
Jackman clematis, Clematis jackmanii
BELOW: Lonicera sempervirens, Trumpet Honeysuckle
a native vine with coral flowers loved by hummingbirds and butterflies!

Ways to Help Out
As a Public Service Major, we are always looking for cool ways to bring people together rooted in a common cause. Lets say a community is outraged by the amount of nitrogen run off in their town due to the use of chemical herbicides which were used to eradicate the invasive species of Japanese Honeysuckle. In order to exercise non- chemical management control option, you have to have a lot of people willing to perform manual labor. A local nursery or florist shop could organize monthly clean- up days in which you travel around and take out the invasive species. For every clean up, you get a discount at the florist shop so there is an incentive to serve your community. They would need the most amount of volunteers during the peak seasons of mid- July and mid- September when the plant is in bloom. It would take a lot of effort to organize volunteers and make sure each clean- up day had enough people, but in the end it would be worth it.


Uses for Good
Although Japanese Honeysuckle is detrimental to native plant species in the U.S, the plant is beneficial to human health. Traditional Chinese medicine called the vines "ren dong teng" translating to "winter enduring vine." The flowers are called "jin yin hua" meaning "gold and silver flowers." The vines and flowers contain consitituents including luteolin, alkaloids, and chlorogenic acid. Cholorogenic acid gives Japanese Honeysuckle its anti-bacterial properties whereas luteolin gives anti-inflammatory properties. The flowers are mixed with Forsythia powder to create a formula that is used to cure fevers, headaches, coughs, thirsts, and sore throats. Japanese Honeysuckle and Forsythia are combined because the Chinese believe they have "synergistic medicinal effects." They are considered "paired herbs."

Today, Japanese Honeysuckle is a proven antibiotic for bacteria such as staphylococcus, aureus, escherichia coli, vibrio cholera, salmonella typhi, diplococcus pneumoniae, to name a few. The plant prevents serious illnesses that cause death in humans. Japanese Honeysuckle is also used as a mild laxative to cleanse the digestive tract. It promotes bowel movements and acts as a diuretic that promotes urine flow.