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December 04, 2016
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New invasive plant: Battling mile-a-minute vine

The mile-a-minute vine has been classified as an invasive plant. (Photo by Les Merhoff)

UPPER DELAWARE RIVER VALLEY — A new non-native plant species has arrived in the Upper Delaware River valley region—mile-a-minute vine (MAM). This plant is listed on the Pennsylvania Noxious Weed List because it can “directly or indirectly injure crops, other useful plants, livestock, poultry or other interests of agriculture, including irrigation, navigation, fish and wildlife resources, or the public health.” Early detection and rapid response is the best defense to the spread of this aggressive invader. Summer is the ideal time to enlist the aid of the public in documenting the location of MAM infestations as they enjoy the outdoors and recreate along the river.

Mile-a-minute vine gets its name from the fact that this annual vine can grow up to six inches in one day and can reach over 20 feet long in one growing season. Also known as Asiatic tearthumb, the barbed stems and prickly leaves allow the vine to easily climb over surrounding vegetation, forming dense, tangled mats that shade out the sun and choke underlying plants. It is considered an invasive species because of its superior competitive ability compared to the local native plant community. In addition to a rapid growth rate, mile-a-minute vine produces numerous fleshy, berry-like, iridescent blue seeds from June through the first fall frost. These seeds are easily dispersed by water, birds, mammals and humans and they can also float.

Mile-a-minute vine was accidentally introduced to York County, PA in the 1930s, when it hitched a ride with nursery stock imported from eastern Asia. Within the Delaware River Valley, the National Park Service at Upper Delaware Scenic & Recreational River (UPDE) discovered MAM for the first time in 2011 growing on the riverbank just downstream of the Lackawaxen boat access. In 2012, Wayne Conservation District (WCD) found the unusual vine growing along the Lackawaxen River in Honesdale. In September, 2013, the National Park Service noticed that this pesky plant had jumped the state line and was growing in close proximity to the Delaware River, in Cochecton, NY. This discovery was the first documented location for MAM in Sullivan County, NY and was promptly reported to the Catskill Regional Invasive Species Partnership (CRISP). Now all three organizations are partnering to find out if there is more mile-a-minute vine growing in our region, get it mapped and documented, and assist in its removal when possible.

Officials urge residents to report sightings of the plant. Mile-a-minute should be easy to spot, especially now. The vine is producing its pea-sized green fruit, which will soon be turning into the blue, iridescent seeds once fully ripe. The characteristic pale green triangular leaves (approximately two to three inches long and two to three-and-a-half inches wide) alternate along a narrow reddish stem armed with downward pointing barbs and distinctive funnel-shaped leafy structures, called ocrea, surrounding the stem at the leaf nodes.
Report any discoveries to resource management staff at Wayne Conservation District, Catskill Regional Invasive Species Partnership and/or Upper Delaware Scenic & Recreational River. If a resident spots mile-a-minute vine growing in the Upper Delaware River region, or if residents think they have it growing on their property, they can call 570/253-0930 for WCD, 845/586-2611for CRISP, especially if found in Sullivan County, NY, or 570/729-7842 for UPDE.

For more information on the biology and distribution of MAM in the eastern United States visit For a story on knotweed, another dangerous invasive in the region, see this week’s Our Country Home supplement.