| Lonicera japonica | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Dipsacales |
| Family: | Caprifoliaceae |
| Genus: | Lonicera |
| Species: | L. japonica |
| Binomial name | |
| Lonicera japonica | |
| Synonyms[1] | |
| |
Lonicera japonica, known asJapanese honeysuckle[2] andgolden-and-silver honeysuckle,[3] is a species ofhoneysuckle native to East Asia, including many parts of China. It is often grown as an ornamental plant, but has become aninvasive species in a number of countries. It is used in traditional Chinese medicine.
Lonicera japonica is a twiningvine[4] able to climb up to 10 m (33 ft) high or more intrees, with opposite, simple ovalleaves 3–8 cm (1+1⁄4–3+1⁄4 in) long and2–3 cm (3⁄4–1+1⁄4 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.[5]
Theflowers are double-tongued, opening white and fading to yellow, and sweetly vanilla scented. Thefruit, which is produced in fall,[5] is a black sphericalberry3–4 mm (1⁄8–3⁄16 in) diameter containing a fewseeds.[6]
Lonicera japonica containsmethyl caffeate,3,4-di-O-caffeoylquinic acid,methyl 3,4-di-O-caffeoylquinate,protocatechuic acid,methyl chlorogenic acid, andluteolin. The two biflavonoids,3′-O-methyl loniflavone andloniflavone, along with luteolin andchrysin, can be isolated from the leaves.[7] Other phenolic compounds present in the plant arehyperoside,chlorogenic acid, andcaffeic acid.[8] The two secoiridoid glycosides,loniceracetalides A andB, can be isolated, together with 10 known iridoid glycosides, from the flower buds.[9] The plant also contains the saponinsloniceroside A andB[10] and the anti-inflammatoryloniceroside C.[11]
There are threesubspecies ofLonicera japonica:
| Image | Subspecies | Description | Distribution |
|---|---|---|---|
 | Lonicera japonica var.chinensis(P.Watson) Baker | Corolla purple outside, white inside. Usually diploid 2n=18 | China (Anhui, 安徽省 in Chinese) around 800 meters[12] |
 | Lonicera japonica var.japonica | Vigorous vine, Corolla white, later yellow-white. Usually diploid 2n=18 | Grows on the edge of forest in China, Japan, and Korea[13] |
| Lonicera japonica var. miyagusukianaMakino | Tetraploid with chromosome number of 2n=36 | Found in tops of exposed windy limestone cliffs in Ryukyus Islands, Japan[14] |
The flowers can also be a significant source of food for deer, rabbits, hummingbirds, and other wildlife.[15]
Japanese honeysuckle has become naturalized in Argentina, Australia, Brazil, Mexico, New Zealand, and much of the United States, including Hawaii, as well as a number of Pacific and Caribbean islands. It is classified as a noxious weed in 46 states, Prohibited to be bought and sold in Connecticut, Illinois, Massachusetts, and Vermont, and banned in Indiana and New Hampshire.[16][17][18] It is listed on the New ZealandNational Pest Plant Accord as an unwanted organism.[19]
Lonicera japonica was initially brought to the U.S. from Japan in the early 1800s as an ornamental plant. It is still deliberately planted in the U.S. for reasons such as erosion control or forage for deer, but has become invasive in many areas.[5] 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.[20] Once it has invaded an area,Lonicera japonica grows rapidly and outcompetes native plants for sunlight and nutrients.[5] It proliferates using bothsexual andvegetative reproduction, producing seeds that are spread by animals and expanding locally viarhizomes.[21] Eventually, it will form a dense thicket which prevents other plant species from germinating in that area.[5] Due to its suppression of germination in the understory,Lonicera japonica also prevents the regeneration of trees.[22]
Management of invasiveLonicera japonica has been achieved through a variety of means. Small patches can be removed by hand, or using simple digging tools,[21] but all plant parts including roots and rhizomes must be removed to prevent resprouting.[5] Larger patches can be removed through repeated mowing, but application of herbicide is also recommended to prevent regrowth.[21] There has been some study of usingcontrolled burns to removeL. japonica, but the underground portion of the plant is usually able to survive and resprout, limiting the effectiveness of this method.[5] Browsing by herbivores may limit its growth, but is unlikely to fully eliminate it.[22]
The EPA of New Zealand approved the release ofLimenitis glorifica butterflies in 2013 as abiological control forLonicera japonica. This butterfly is host specific for Japanese honeysuckle, but it may incidentally feed on other closely related plants, including Himalayan honeysuckleLeycesteria formosa.[23]Oberea shirahatai is a Japanese honeysuckle host-specific beetle that feeds on the stems and leaves of Japanese honeysuckle. It was released in New Zealand in 2018 as anotherL. japonica-specialist biological control.[24]
Even though it is a highly invasive and destructive plant,[25] this species is often sold by American nurseries as thecultivar 'Hall's Prolific' (Lonicera japonica var.halliana),[citation needed] and in the UK as the cultivar 'Halliana'. The cultivar is also known as Hall's Japanese honeysuckle.[26] It is an effectivegroundcover and has strong-smelling flowers. It can be cultivated byseed,cuttings, orlayering. In addition, it will spread itself viashoots if given enough space to grow. The varietyL. japonica var.repens[27] has gained theRoyal Horticultural Society'sAward of Garden Merit.[28]
All parts of the plant other than the flower nectar have the potential to be toxic.[29]
Japanese honeysuckle flowers are edible to humans and appreciated for their sweet-tasting nectar.[citation needed]
Intraditional Chinese medicine,[30]Lonicera japonica is calledrěn dōng téng (忍冬藤);[30] literally "winter enduring vine") orjīn yín huā[30] (Chinese:金銀花; literally "gold-silver flower", in reference to the presence of flowers of different age on the same plant as each flower change from white (silver) to yellow (gold)).[citation needed] Alternative Chinese names includeer hua (二花) andshuang hua (雙花), meaningdouble-[color] flowers.[31][32]