Kitty Kohout, UWI

Louis' Swallowwort
Cynanchum louiseae

Louis' swallowwort is native to Europe, and may have been introduced intentionally for ornamental purposes or imported unintentionally on other plants or materials. Louis' swallowwort occurs in the northeastern and mid-Atlantic states to the Midwest, and in California, where it threatens native flora in fields, forest edges, woods and open disturbed areas. It grows vigorously and densely, blocking light from reaching the plants it scrambles across, often leading to their death. Swallowwort spreads vegetatively and by seeds dispersed by the wind. Because there are many native milkweed species in the United States, correct identification of this plant is imperative.

Prevention and Control
Do not plant this or other exotic swallowworts. Plants can be pulled by hand or mowed, once or twice per season, or dug up, removing the entire crown. Picking of pods is used as a last resort to help prevent production and spread of seeds. Application of systemic herbicides like glyphosate and triclopyr is also effective.

Native Alternatives
pipevine (Aristolochia macrophylla), swamp milkweed (Asclepias incarnata), butterflyweed (Asclepias tuberosa)

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Publication by USFWS BayScapes Conservation Landscaping Program
http://www.nps.gov/plants/alien/pubs/midatlantic/cylo.htm
Last updated: 7 October 2004