mile-a-minute vine

Mile-a-Minute (Polygonum perfoliatum L)
Alternate Common Names:
Mile-a-minute Weed; Mile-a-minute;
Devil’s or Asiatic Tearthumb

  • Triangular leaves—equilateral triangles
  • Tiny barbs on stems
  • Vine
IF YOU SEE IT, REPORT IT: triangles (equilateral), barbs (tiny), on a vine

Mile-a-Minute Vine can always be recognized by its equilateral triangular leaves and the tiny prickles or barbs on the stems. The size of the triangles varies with the age and vigor of the plant, but the shape remains the same. There are other vines with (almost) equilateral triangular leaves and there are other vines with tiny barbs, but only Mile-a-Minute has both.

Please report all sightings to knelson151@sbcglobal.net or donna.ellis@uconn.edu or The Connecticut Invasive Plant Working Group at 860-486-6448 so we can track the spread of MAM vine.

Mile-a-Minute seeds sprout in spring — early April in New Milford. At first the plants seem innocuous, with their thread-like stems, tiny triangular leaves, and tiny barbs. Vines are only a few inches long by mid-May, around 3 feet long in early June, and 6 feet and rising by the first day of summer. In 2007 and 2008 in New Milford, flower buds were produced as early as the 25th of June.

As the season goes on, plants grow faster and faster, up to six inches a day (think about that!), with vines climbing 20 feet or more up trees and over shrubs. Mile-a-Minute continues to produce flowers and fruits until killed by frost.

There are other distinguishing characteristics people use when searching for MAM. In spring, the leaf-like, saucer-shaped ocreae are very noticeable. They surround the stems at each point where a leaf is attached. The petiole, the tiny stem to each leaf, is attached just under the edge of the leaf, rather than to the edge. The clusters of tiny flowers aren’t showy. Clusters of bright blueberry-like ripe fruits are easily noticed, but we hope you never see them. Each fruit is about 5 mm in diameter. Stems are often reddish in color and may catch the eye in the fall after leaves are killed by frost. Note that MAM climbs by hooking its way up by the barbs — it is not a twining vine.

Two characteristics that experienced MAM searchers use are difficult to describe. One is the distinctive color, but people describe it differently. They all seem to agree on pale, but some say blue-green, others yellow-green. Look at a picture and decide for yourself what to call it.

Another useful feature for identification is the way the stems keep reaching upward. Other vines often send stems searching off to the side while MAM plants reach upward. In August, it may be possible to recognize MAM stems reaching up from a clump of multiflora rose or a forsythia hedge from quite a distance away. This doesn’t work as well in September, when another type of vine sends up vertical spikes of flowers.

Mile-a-minute Vine seeds sprout and grow almost everywhere. Some people will tell you they don’t grow in shade. Forget that. Although they may not survive really dark shade, there are many plants per square foot in one of the woodland areas where we work. They love the shade under shrubs such as multiflora rose, which is a serious problem, because they often hide within these massive shrubs until late in the season, when they burst forth into the sunlight growing 6 inches a day and dropping thousands of seeds.

Although the plants grow fastest in full sun without competition, they will grow and produce seeds almost anywhere. We found tiny plants full of seeds between stems of 5 ft tall goldenrod in a dense meadow. We found many plants per square foot on an almost vertical bank carved into the subsoil, dusty dry, with multiflora rose and brambles, under the shade of a large tree. The plants were skinny and the leaves tiny – you almost needed a magnifying glass to find them – but they were full of seeds.

The only places we haven’t seen MAM plants growing are 1) lawn, 2) the deepest, darkest shade, and 3) with roots in the water.

The vine smothers herbaceous plants, shrubs, and young trees in meadows, forest edges, some woodlands, logged forests, stream banks, and utility rights-of-way. The fruits float and are eaten by birds, small mammals, and deer.

Movement of topsoil is one of the primary ways seeds spread long distances. Several persons have reported seedlings appearing in newly landscaped areas.

Seeds carried in water are a particular threat. Between 2004 and 2007 MAM covered several acres of floodplain and river corridor in Newtown, CT. It may be impossible to prevent it from infesting the entire river corridor.

REPORT ALL SIGHTINGS to knelson151@sbcglobal.net or donna.ellis@uconn.edu or The Connecticut Invasive Plant Working Group at 860-486-6448.