Pale Swallowwort

Cynanchum rossicum

Common Name: Pale swallowwort (a.k.a. Russian swallowwort)
Scientific Name: Cynanchum rossicum
Family: Asclepiadaceae
Growth Form: Herbaceous vine
Native Range: Eastern Europe
Alien Range: Northeastern United States and Canada
Introduction: Pale swallowwort was introduced as an ornamental plant in the late 1800s.  It has since escaped from cultivation and spread by seed.
Description: ·Leaves: Simple, opposite and smooth with entire margins.  5-10 cm (2-4 in.) Oblong or ovate in shape.  Dark green.

·Stem: Smooth, un-branched.  Can wind around other plants and trees, growing 1-2 m (3-6 ft.) long.

·Flowers: Maroon, dark pink, or yellowish brown, corolla of 5 lobes.  Lobes thick and triangular.  Hairless.  Inflorescences of 6-10 flowers occur at leaf axils from .5-1.5 cm (.25-.5 in.) stalks.  Present from June to September. 

·Fruit: Green pod. Light brown when mature. Paired.  4-7 cm (2-3 in.) long; thin, elliptical shape.  Persist through winter. Contain flat, brown, elliptical seeds.  5-7 mm long.  Tuft of fine hair at one end.
Threats: Forms dense stands in disturbed areas such as Christmas tree plantations, nursery crops, alfalfa and conservation habitats.  Shades out native vegetation, reduces biodiversity, can strangle trees and shrubs as it winds around them.  Displaces goldenrod, which is a host plant for Monarch butterfly eggs.
Fun Facts: Some people are allergic to the sap of pale swallowwort.  It causes redness, itching, and swelling.
English ivy on a tree
English ivy taking over a tree