
Lonicera maackii, the Amur honeysuckle, is a species of honeysuckle in the family Caprifoliaceae that is native to temperate eastern Asia; specifically in northern and western China south to Yunnan, Mongolia, Primorsky Krai in southeastern Siberia, Korea, and, albeit rare there, central and northern Honshū, Japan. Lonicera maackii is a listed endangered species in Japan. It has escaped from cultivation and naturalized in New Zealand and the eastern United States; in the woodlands of the U.S. it is a significant invasive species. The plant is a large, deciduous shrub that grows a maximum of 6 metres (20 ft) tall with stems of a maximum of 10 centimetres (4 in) in diameter. The leaves are oppositely arranged, 5–9 centimetres (2–3+1⁄2 in) long and 2–4 centimetres (3⁄4–1+5⁄8 in) broad, with an entire margin, and with at least some rough pubescence. The flowers are produced in pairs; they are 2 centimetres (3⁄4 in) long, have two lips, begin white and later turn yellow or pale orange in color; they bloom from middle of spring to early summer. The fruit is a bright red to black, semi-translucent berry, 2–6 millimetres (5⁄64–15⁄64 in) in diameter, that contains numerous small seeds. The species name "maackii" is derived from Richard Maack, a Russian naturalist of the 19th century. Its common name "Amur honeysuckle" is from its native range surrounding the Amur River, which demarcates the border between Siberia and Manchuria. Some Internet sources name the species authority as "(Rupr.) Herder", but the correct authority is "(Rupr.) Maxim". Amur honeysuckle is cultivated as an ornamental plant for its attractive flowers and as a hedge. Many cultivars have been selected for horticulture, including "Erubescens" with pink flowers and "Rem Red" with an erect form. The plant is adaptable and flourishes in a wide range of conditions. In the United States, it was planted to control erosion and to form hedges. It readily self-propagates via birds dispersing its seeds, and quickly spreads into habitats for which it has no community connectivity. It grows rapidly and prefers shady habitats such as woodland understories, neglected urban areas, and fence rows. It can form very dense thickets.