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Persicaria perfoliata

mile-a-minute weed

SunFull Sun – Part Shade

Overview

Persicaria perfoliata is a fast-growing annual vine in the knotweed family, with thin, reddish stems that can extend 20-25 feet (6-8 m) in a single season. The stems and leaf stalks are armed with small, downward-curved barbs that catch on surrounding vegetation and let the plant scramble upward. Leaves are pale green and triangular, 1-3 inches (2.5-7 cm) wide, attached at the petiole so they appear to point backward. A diagnostic feature is the series of cup-shaped leafy structures, called ocreae, that surround the stem at intervals, with flower and fruit clusters emerging from them. The small white-to-greenish flowers are inconspicuous and give way to segmented spikes of metallic blue, berry-like fruits about 0.2 inch (5 mm) across. Each fruit contains a single glossy black or reddish seed. The plant climbs over shrubs and young trees, forming dense mats that shade out the plants beneath, and it is listed as a noxious or invasive species across much of the eastern United States. Seeds remain viable in soil for up to six years and spread by water, birds, and ants, which makes established infestations hard to remove.

Native Range

Native to eastern Asia, ranging from India and Nepal through China, Korea, Japan, and the Philippines. In its native range it grows along streambanks, forest edges, and disturbed ground.

Suggested Uses

Persicaria perfoliata has no horticultural use and is managed as an invasive species rather than planted. It is included in plant references for identification so that infestations can be recognized and reported in areas where it is regulated.

How to Identify

Identified by triangular pale-green leaves attached at the petiole, reddish stems lined with downward-curved barbs, and circular cup-shaped ocreae clasping the stem at intervals. Clusters of metallic blue, berry-like fruits about 0.2 inch (5 mm) across emerge from the ocreae in late summer. The pairing of barbed stems, triangular leaves, and blue fruits separates it from native smartweeds and other vines.

Appearance

Size & Dimensions

Height20' - 25'

Width/Spread6' - 10'

Colors

Flower Colors

white

green

Foliage Colors

green

Bloom Information

Bloom Period

~10 weeks

Summer

Flowers from June through August in eastern North America, with small white-to-greenish flowers that are easily overlooked. Metallic blue fruits develop from July into October. A single plant can produce several hundred seeds across the season.

Detailed Descriptions

Flower Description

white to greenish

Foliage Description

pale green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.5(Neutral)

357912

Soil Types

loam clay silt

Drainagemoist

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Persicaria perfoliata grows in full sun to partial shade and favors moist soils along streams, wetland margins, roadsides, and clearings. It germinates in early spring once soil temperatures rise and grows rapidly, climbing over any available support. The plant tolerates a range of soil types but is most aggressive on damp, fertile ground in open light. It completes its life cycle in a single year, setting seed before frost kills the foliage. Control programs rely on removing seedlings before fruit forms and cutting vines through the season, because the long-lived seed bank allows reinfestation for several years. It is regulated as a noxious weed in numerous states, and planting it is prohibited in those jurisdictions.

Pruning

Cutting or mowing vines repeatedly through the growing season reduces seed production and slows spread. Cutting is most useful before the blue fruits form in midsummer. Because the plant is an annual, clearing it before seed set prevents return the following year where the seed bank is not yet established.

✓ Toxicity

Non-toxic