Pale swallow-wort (Vincetoxicum rossicum)

Synonyms: Cynanchum rossicum

Common Names: Dog-strangling vine, European swallowwort

Description: Grows rapidly over native vegetation; wind-dispersed seed travels long distances.

Habit: Herbaceous perennials, both range from 0.6-1.8 m (2-6 ft) tall.

Leaves: Simple, opposite, narrow, oblong to ovate with a pointed tip, dark green leaves with a smooth, waxy coating; emits a pungent herbal smell when crushed.

Stems: Twining; may climb or creep around adjacent plants.

Flowers: Small, five-petaled; clustered in leaf axils; slight rotting odor; pale to dark maroon, purple or pink; glabrous; peduncles 2-5 mm; blooms June through August.

Fruit and seeds: Seed pod, resemble those of milkweed, pods split open in mid-summer to release wind-borne seeds.

Habitat: Native to southern Europe. Found in hardwood forests, shaded woods, open prairies, fields, savannas, roadsides; can tolerate a range of light and soil conditions.

Reproduction: By seed, vegetatively by rhizomes and shoots from root crown of parent plant.

Similar species: Native dogbanes (Apocynum spp.) have similar seedpods but are not vines.

Monitoring and rapid response: Monitor disturbed sites and also edges and paths in undisturbed sites; populations most visible in late summer when the leaves turn golden and seedpods appear. Hand-pulling difficult as roots are fragile, digging preferred, remove roots from site. Foliar herbicide treatment provides effective control; cut-stem herbicide application provides slightly less effective control and is labor intensive. Prescribed fire is not effective when used alone and may improve conditions for increased germination; fire may be useful following herbicide application to control seedlings with less developed root systems. Remove and burn seedpods; multi-year monitoring and follow-up required. Please report sightings with GPS positions to Dr. DiTommaso at: ad97@cornell.edu.

Credits: The Michigan Natural Features Inventory (MNFI) has partnered with MISIN to provide the information in this fact sheet. Species images and/or information were used with permission from "A Field Identification Guide to Invasive Plants in Michigan's Natural Communities" and "A Field Guide to Invasive Plants of Aquatic and Wetland Habitats for Michigan.

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