NISAW: Invasive Plant Spotlight

Mile-A-Minute Weed (Persicaria perfoliate)

The Maine Natural Areas Program (MNAP) of the Maine Department of Agriculture, Conservation, and Forestry (DACF) encourages the public to report any sightings of the invasive mile-a-minute vine (Persicaria perfoliate), also known as devil’s tearthumb. Mostly seen in gardens from hitchhiking in nursery pots or greenhouse soil, this vine has the potential to take over several important Maine habitats if not detected and eradicated.

Images (Left) Mile-a-minute’s pea-sized fruits that ripen blue and are cradled by the circular stem leaf. (Right) The leaf shape of mile-a-minute vine is extremely triangular.

Mile-a-minute is an herbaceous annual vine that is native to Eastern Asia and can grow up to 6 inches per day. This plant has alternate light green leaves that are triangular. The vines and underside of the leaves have curved barbs that allow them to climb over trees and other plants for better access to the sun. Another identifying feature are the circular leaves that wrap around stem nodes, called ocrea, where small flowers and pea-sized fruits develop from. Fruits ripen to blue and contain a black seed, which are easily spread to new locations by deer, small mammals, and especially birds. The fruits and seeds can float in water for approximately one week, being spread by streams and rainfall. This plant has a significant potential to invade most of Maine, as it requires an 8-week cold period to flower, and the plant has been spotted and pulled from a few locations already. Mile-a-minute forms dense mats that weaken other plants and causes poor growth from blocking sunlight, ultimately decreasing native vegetation. Mile-a-minute can degrade reforestation efforts, forest stands, and invade most disturbed areas. This plant can be found in wet or dry soils, allowing it to invade many habitats in Maine.

Other vines in Maine may look similar to mile-a-minute, so be sure to identify the ocrea, the curved barbs along the stems, and the very triangular leaves. Some look-alikes include commonly found native and non-native bindweeds, and native tearthumbs such as arrow-leaved tearthumb (P. sagittate) and Halberd-leaved tearthumb (P. arifolia).

If you believe you have found mile-a-minute vine or would like to learn more, please contact [email protected] with the location and photos of your sighting. It’s encouraged to submit your sightings to iMapinvasives to further our understanding of where it is present. Please visit the Maine Natural Areas Program’s website under the Invasive Species tab to learn more about other invasive species in Maine, or read our mile-a-minute fact sheet.

Image (Above) Mile-a-minute infestation forming dense mats, taking over trees and shrubs to compete for sunlight. Image: USDA APHIS PPQ Archive, Bugwood.org