Several species of swallow-worts are herbaceous, perennial vines that invade natural areas in northeastern United States. Leaves are opposite, dark green, oval, and shiny with entire margins. Flowers occur in clusters and dark purple in color. Fruit are pods, similar to milkweed pods, that are slender and split to reveal small seeds with tufts of white hair. The hair allows the seeds to be readily dispersed by seeds. Swallow-worts invade a wide varierty of habitats including old fields, open woodlands, pastures, roadsides, and floodplains. It can rapidly overgrow native understory vegetation and small shrubs, forming dense mats which smother and kill other vegetation. Swallow-worts are native to Europe and were first introduced in the United States in the late 1800s as ornamentals.

Resources

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• Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service
• Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service

Selected Images

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Maps

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Invasive Listing Sources

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• City of Ann Arbor Michigan Parks and Recreation
• Ontario’s Invading Species Awareness Program Tracked Species List

References

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Common Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.

Scientific Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.