Pale Swallow-Wort

Cynanchum rossicum (Kleopow) Borhidi
Milkweed family (Asclepidaceae)

Origin: Endemic to southwestern European Russia in regions north of the Black Sea and the Caucasus

The first collections of pale swallow-wort in the northeastern United States were from Monroe and Nassau counties New York in 1897. Canadian records indicate that it was established and probably naturalized in southern Canada since the early 1900s.

John M. Randall, The Nature Conservancy

Distribution and Habitat
Pale swallow-wort, also known as dog-strangling vine, occurs in southern Ontario, Montreal and west Quebec and the northeastern United States from southern Maine to northern Maryland with scattered occurrences in the Great Lakes and Midwest. It is widely distributed in central New York State. It is associated with calcareous soils in upland areas and is found in forest understory, pastures, old fields, shores, flood plains and disturbed areas. Ecosystems on well-drained, stony soils are often densely colonized but it can tolerate a wide moisture regime. Plants establish in full sun or under forest canopies and can form dense stands in all light conditions.

Ecological Threat
Pale swallow-wort is a threat to native flora in forests, forest edges, fields, and open disturbed areas where it grows vigorously and forms dense patches that cover and shade out native plants. It smothers and kills vegetation and reduce invertebrate and vertebrate biodiversity.

Description and Biology

Prevention and Control
Do not purchase or plant this species. Plants can be pulled by hand or mowed, once or twice per season, or dug up, removing the roots. The most effective control is with herbicides, because mechanical control of this plant is difficult, labor-intensive and time-consuming. Systemic herbicides containing glyphosate or triclopyr are most effective because they kill the entire plant including the roots (see Control Options). No biological control agents are available for this plant.

Native Alternatives
Honeyvine (Cynanchum laeve), if available, coral honeysuckle (Lonicera sempervirens) and pipevine (Aristolochia macrophylla) make suitable alternatives.


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Last updated:11-Nov-2010