|Foliage and flowers in spring|
Lonicera maackii (Overgrowing Choke-plant or Amur honeysuckle) is a species of honeysuckle in the family Caprifoliaceae, native to temperate Asia in northern and western China (south to Yunnan), Mongolia, Japan (central and northern Honshū, rare), Korea, and southeastern Russia (Primorsky Krai).
This overpopulated plant in North America is causing the destruction of many native species. It may be listed as an endangered species in Japan, but has been the bane of many botanists and biologists in North America due to its invasive nature. It has escaped from cultivation and become naturalized in New Zealand and the eastern United States; in the forests of the latter, it has become an important invasive species.
It is a deciduous large shrub growing to 6 m tall with stems up to 10 centimeters diameter. The leaves are oppositely arranged, 5–9 cm long and 2–4 cm broad, with an entire margin, and with at least some rough hairs on them. The flowers are produced in pairs, commonly with several pairs grouped together in clusters; they are 2 cm long, two-lipped, white later turning yellow or light orange in color; flowering is from mid spring to early summer.
The fruit is a bright red to black semi-translucent berry 2–6 mm diameter containing numerous small seeds; they ripen in autumn, and are eaten by birds, which disperse the seeds in their droppings. It is fast growing and favours shady habitats such as the forest understory, neglected urban areas, and fence rows. It can form extremely dense thickets.
Cultivation and uses
It is grown as an ornamental plant for its attractive flowers, and also as a hedge. A number of cultivars have been selected for garden use, including 'Erubescens' with pink flowers, and 'Rem Red' with erect habit.
The flowers are sometimes used by children, who remove the blossom by hand, and pull off the bottom to suck out the sweet nectar in the center. The red berries are mildly poisonous to humans and should not be eaten.
As an invasive species
Spread of this plant is illegal or controlled in some areas of the United States due to its well documented invasive character. It is listed as a "invasive, banned" species in Connecticut, "prohibited" in Massachusetts, and a "Class B noxious weed" in Vermont. It is also officially listed as an invasive species by government agencies in Wisconsin and Tennessee.
This plant is adaptable and successful in a wide range of conditions. In the United States, Amur honeysuckle was once planted to control erosion, and as hedges. It spread quickly as birds eat the fruit and disperse the seeds, and was soon naturalized. Notably, in deciduous forest understories of the eastern United States it forms dense growths with thick canopies that shade out native shrubs, young trees, and wild flowers. Uncontrolled, these growths create a near monoculture of Amur honeysuckle. This species poses a serious threat not only to the diversity of the ecosystems which they invade but also to forest regeneration itself, as the plant is known for reducing the growth and diversity of native seedlings. Moreover, studies have shown that the plant is responsible for having a negative impact on birds, and tadpoles. In 2010 a study in the St. Louis area showed that the plant increases the risk of tick-borne diseases such as Erlichiosis and Lyme disease in suburban natural areas, by attracting deer activity and increasing the number of infected ticks. Furthermore, experimental removal of the plant was shown to reduce deer activity and number of infected ticks, through the shifting of ticks' blood meals away from deer.
Honeysuckle can be controlled by cutting, flaming, or burning the plant to root level and repeating on two-week increments until nutrient reserves in the roots are depleted. To ensure eradication, newly cut stumps should be treated with herbicide. Control through prescribed burning has been found to be most effective during the seed dispersal phase (late summer and early fall). Honeysuckle can also be controlled through annual applications of glyphosate which thoroughly soak the leaves, or through grubbing of the shallowly rooted young plants. Both of these methods are only practical if high labor costs and soil damage are not of concern.
Due to the invasive nature of this species and the ecological threat it poses, it may be inadvisable to cultivate this plant in climates similar to those found where this species has become invasive (e.g. eastern United States). It has been suggested that existing specimens found outside of their native range in east Asia should be removed and replaced with alternative non-invasive species. Possible alternative fast growing, shade tolerant, deciduous shrubs include Calycanthus floridus, Cornus mas, Cornus sericea, Forsythia hybrids, Hydrangea spp., Syringa vulgaris, Viburnum cassinoides, Viburnum dentatum, Viburnum dilatatum, Viburnum opulus, Viburnum prunifolium, Viburnum trilobum, Weigela florida.
The common name Amur honeysuckle comes from the Amur River which is the world's eighth longest river. This river forms the border between the Russian Far East and Manchuria in China. L. maackii is native to the area surrounding this river. The species name maackii is derived from Richard Maack, a 19th-century Russian naturalist.
|Wikimedia Commons has media related to Lonicera maackii.|
- "The Plant List: A Working List of All Plant Species". Retrieved 7 December 2014.
- Germplasm Resources Information Network: Lonicera maackii
- Ministry of the Environment (Japan): Red List of Threatened Plants of Japan (excel spreadsheet)
- Red Data Book (Japan): Lonicera maackii (in Japanese, with map; google translation)
- USDA Forest Service Weed of the Week Fact Sheet (pdf file)
- Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.
- Missouriplants: Lonicera maackii
- Invasive.org: Lonicera species (pdf file)
- Annotated Bibliography of primary research on invasive qualities of L. maackii in the USA: National Biological Information Infrastructure
- University of Connecticut Plant Database: L. maackii
- Ohio State University Pocket Gardener: L. maackii
- USDA PLANTS DATABASE: L. maackii