Gallery_2_Mile-a-Minute | PA iMapInvasives

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Photo credit: Lindley Ashline/Flickr

Mile-a-Minute

(Persicaria perfoliata)

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Species at a Glance

Mile-a-minute, also called Asiatic tearthumb, is an herbaceous, annual, trailing vine that can reach lengths of up to 6 m (20 ft). It survives by using its recurved barbs to attach to and climb over other plants in order to reach areas of high light intensity, smothering and weakening them in the process.

Identification

Leaves: Light green leaves are shaped like distinctive equilateral triangles. They are 3-8 cm (1.2-3.1 in) in length, alternate along a thin delicate stem, and have barbs on the undersides. Circular, cup-shaped, leafy structures called ocrea surround the stem at each node where flower buds, late flowers, and fruits emerge.

Flowers: Small, white, and generally inconspicuous.

Fruits/Seeds: Attractive, deep metallic blue, berry-like fruits are arranged in clusters with each fruit containing a single glossy black or reddish-black hard seed.

Stems/Roots: Delicate, thin, reddish stems have curved downward pointing barbs.

Similar Species

Some native vine species, including native tearthumbs, may be confused with mile-a-minute; however, they lack the equilateral triangle-shaped leaves and the blue berry-like fruits.

Habitat

Mile-a-minute generally colonizes open and disturbed areas along the edges of woods, wetlands, stream banks, roadsides, and uncultivated open fields. It prefers extremely wet environments with poor soil structure and full sunlight, although it will tolerate shade for part of the day.

Spread

This self-pollinator produces a large number of seeds that can persist in the soil for up to six years. Birds, ants, small mammals, and water are the primary dispersal methods. Fruits can remain buoyant in streams or rivers for 7-9 days, allowing mile-a-minute to disburse over long distances.

Distribution

Native to India and eastern Asia, the first successful population of this vine in the United States was in York, Pennsylvania in the late 1930s. Today Mile-a-minute has spread to all states in the Mid-Atlantic region, as well as Ohio, Kentucky, Massachusetts, and Oregon.

Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.

Environmental Impacts

Mile-a-minute grows rapidly, overtaking shrubs and other native vegetation by reducing their access to sunlight and destroying their stems and branches by its added weight and pressure. It also poses problems for nursery and horticulture crops, Christmas tree farms, and forestry operations.