Amur honeysuckle arrived in America as an ornamental shrub; it later became a major invasive concern in forests across the northern United States

Amur honeysuckle, a leafy shrub native to eastern Asia, was imported to the United States in the late 19th century as an ornamental plant, valued for the quick, dense cover it gave to new landscaping. Today it is a staple inclusion on invasive-species watch lists across the Midwest and elsewhere. If you've ever hiked a wooded trail during early spring and run into one stubborn green layer already leafed out while all the rest was still bare, you may have met it.

The scale of the cleanup effort is a sign of how far it has come. According to a 2013 U.S. Forest Service report by Cassandra Kurtz, federal researchers tracked 50 invasive plant species on forested plots across 24 northern states between 2005 and 2010, and separately included data on nonnative bush honeysuckles, the group Amur honeysuckle belongs to. A shrub that began its journey as decoration had come to be a national forest inventory's concern.

How a garden favorite began its journey


Its arrival in the United States was a matter of policy, not accident. Amur honeysuckle was introduced to the United States in 1898 as an ornamental plant, per a University of Illinois article; it was also planted for erosion control and as wildlife habitat. The U.S. Department of Agriculture went further, promoting the shrub from 1960 to 1984 and developing “improved” cultivars, selected for traits like heavier fruit production, that contributed to its invasiveness, according to the Missouri Botanical Garden.

The head start problem

Its competitive edge begins in early spring, when it leafs out before most native plants have greened and quickly forms dense thickets. Severe infestations, the Missouri Botanical Garden notes, can lead to almost complete elimination of native plants. Researchers have measured the impact at the forest-stand level: in a 1997 study titled “Invasibility and Effects of Amur Honeysuckle in Southwestern Ohio Forests,” in Conservation Biology by Todd Hutchinson and John Vankat, surveying 93 forest stands near Oxford, Ohio, found that tree seedling density, seedling species richness, and herb cover all decreased as honeysuckle cover increased. The authors described this as a potential effect on future forest structure and composition, a projection, not a certainty, but one that explains why land managers are paying attention.

Illinois is a hot spot

In the region tracked by federal researchers, Illinois led the way. A 2015 Forest Service research note by Kurtz and Mark Hansen found Illinois had the highest percentage of plots with nonnative bush honeysuckle in the region, 39.9 percent in 2013 data. That figure covers the whole group of bush honeysuckles (Amur, Morrow’s, Tatarian, and showy fly), not Amur honeysuckle alone. The same note found Amur honeysuckle specifically on 3.8 percent of the region’s plots (261 of 6,815 surveyed), and states it is most problematic in the south of the region but is spreading northward.

It's not only about plants

Then there's the connection, making it a public health story as well as an ecology one. A 2010 PNAS study titled “Invasive Honeysuckle Eradication Reduces Tick-Borne Disease Risk by Altering Host Dynamics,” led by Brian Allan, found that white-tailed deer preferred areas invaded by Amur honeysuckle, and those areas had many more ticks infected with the bacteria that cause ehrlichiosis, a tick-borne illness carried by the Lone Star tick. When researchers experimentally removed honeysuckle, deer activity and numbers of infected ticks were reduced.

This finding does not mean a honeysuckle shrub causes disease in any individual. National Geographic’s coverage of the study at the time noted the link involves a much longer chain of ecological cause and effect, and that honeysuckle invasion was one contributing factor among several, not a full explanation for rising case counts. The research was based on woodland sites in Missouri in the late 2000s, so its findings shouldn’t be assumed to apply everywhere. Taken together, the research on Amur honeysuckle shows how a 19th-century landscaping choice can still shape forest ecology, and even public health, more than a century later. Its spread across at least 26 states, and its continued expansion through Illinois and the wider Midwest, has made it one of the most closely tracked invasive shrubs in the eastern United States.