Have You Seen This Plant?

Two new observations of Mile-a-Minute Vine (Persicaria perfoliata, syn. Polygonum perfoliatum) were made in Rhode Island in September 2008, resulting in a total of three known locations, in three Rhode Island municipalities.

Mile-a-Minute Vine was first reported growing wild in Pennsylvania in the late 1930’s, and has spread north from there. Connecticut has eighteen known locations; most of which occur in the southwestern part of the state. Massachusetts has two locations. No sites are known for New Hampshire, Maine or Vermont. For this reason, land conservationists are pushing to eliminate Mile-a-Minute Vine in New England before it becomes pervasive. Experience from Connecticut has shown that while seeds are dispersed by natural means (birds, rodents and water), the primary mode of distribution is through humans moving soil or plant material that contain the seed.

Mile-a-Minute Vine is a highly invasive herbaceous vine that is native to Eastern Asia. The name, Mile-a-Minute Vine, comes from the plant’s ability to grow as much as 6 inches in one day; making Black Swallowwort seem like a slow-growing lichen. By the end of the growing season, plants form dense mats over existing vegetation. Although the species is an annual, vines persist through the winter giving new seedlings an ample armature on which to grow. Successive years of growth result in the death of underlying shrubs and herbaceous vegetation. The plant has been dubbed, “the Kudzu of the north”.

Mile-a-Minute Vine is tolerant of many growing conditions, with a preference for sunny, moist soils. The stem is covered with numerous downward pointing prickles, which give the plant its alternate common name, “Asian Tear-thumb.” The leaves are 1″ to 3” wide, forming a nearly perfect equilateral triangle. Prickles also occur along the mid-vein. A distinctive, saucer shaped leaf encircles the stem at each node. Seeds germinate in early to mid-May, with vines growing throughout the summer. Small white flowers appear in late August, and by September, the plant produces bright metallic blue berries which are fed on by birds and rodents. The fruits are buoyant, so preventing spread along water courses is of primary concern. The dense, barbed growth greatly impairs access to areas for people and wildlife, and some have nick-named Mile-a-Minute Vine “The Velcro Plant” because of the clinging nature of the stems.

Control of small populations is best achieved by hand pulling plants throughout the growing season, before fruit is set (generally mid-June to late September). Seeds remain viable in the soil for about seven years, so sites need annual attention to eradicate the plant. Herbicides, in the form of pre and post-emergent sprays, have also been effective, but must be used with a surfactant, and in accordance with the Label and state pesticide regulations.

Please help find and control this invasive plant. Click on the images above to enlarge the Mile-a-Minute Vine photos taken by Kim Gaffett on Block Island last fall. For more information, or to report a citing, call the Survey office at: (401)874-5800, send an email to: hleeson@rinhs.org, or go to the “RI Invasive Species Portal” at www.rinhs.org; and follow links to “contribute data”.

Several web sites can provide useful information on control and photographs of the plant to aid in identification: www.hort.uconn.edu/cipwg and www.nps.gov/plants/ALIEN/fact/pepe1.htm. 

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