COMMON NAME

Pale swallow-wort


FULL SCIENTIFIC NAME

Cynanchum rossicum (Kleopov) Barbarich


FAMILY NAME COMMON

Milkweed family


FAMILY SCIENTIFIC NAME

Cynanchum rossicum


IMAGES


Close-up of flower

Close-up of flowers

Incursion

Habit

Comparision of flowers of Cynanchum louiseae (top) and Cynanchum rossicum (bottom)

Fruit

Incursion

Close-up of fruit with seeds

NOMENCLATURE/SYNONYMS

Synonyms: Vincetoxicum rossicum (Kleopov) Barbarich
Cynanchum medium auct. non R. Br.
Vincetoxicum medium auct. non (R. Br.) Dcne.


DESCRIPTION

Botanical Glossary

Cynanchum rossicum is an herbaceous, perennial vine that is vegetatively very similar to Cynanchum louiseae. The stems can reach 1.5 m (5 ft.) in length. The leaves are opposite, and ovate and acute in shape. They are 9-12 cm (3.5-4.7 in.) long, and 5-6 cm (2-2.5 in.) wide. The petioles measure 1 cm (0.4 in.) in length. Flowers are borne in opposite, axillary cymes from June to September. The corolla of Cynanchum rossicum is 5-obed, glabrous and ranges in color from maroon to dark pink; its lobes are longer than wide and are shaped like an isosceles triangle. The membrane connecting the segments of the corona is approximately 1/2 the height of the corona. The peduncles are 2-5 cm long. The fruits are slender follicles measuring 4-6 cm long and 0.5 cm wide. Page References Fernald 1176, Gleason & Cronquist 399, Holmgren 374. See reference section below for full citations.


SIMILAR SPECIES

Cynanchum louiseae Kartesz & Ghandi (Black swallow-wort) The chart below shows important character differences between Cynanchum rossicum and Cynanchum louiseae. For images and more information about C. louiseae click here to go to the catalog of species.


REPRODUCTIVE/DISPERSAL MECHANISMS

The seeds of Cynanchum rossicum are dispersed primarily by wind. If they were to fall into moving water, they would float and be transported downstream.


DISTRIBUTION

Cynanchum rossicum is native to Europe where it occurs in different habitats than the similar Cynanchum louiseae. It has been reported from Ontario, Canada. In the United States, has been reported from Missouri, Michigan, Indiana, Pennsylvania, New York and New Jersey. In New England, its range is much more restricted than that of Cynanchum louiseae. However, there are populations in Massachusetts, Connecticut and New Hampshire.


HISTORY OF INTRODUCTION IN NEW ENGLAND

Although its history of introduction in New England is uncertain, the first record for Cynanchum rossicum is from New Haven, Connecticut, in 1881. The plant has most likely spread by wind or by being planted in other locations.


HABITATS IN NEW ENGLAND

Abandoned Field, Early Successional Forest, Edge, Floodplain Forest, Forest Wetland, Pasture, Planted Forest, Roadside, Utility Right-of-Way, Vacant Lot, Yard or Garden

Cynanchum rossicum can be found almost anywhere, including woodlands, fields, and along roadsides, floodplains, urban areas and utility rights-of-way. It grows well in almost any upland situation.


THREATS

Cynanchum rossicum is a vine that can grow rapidly over native vegetation. It also has the ability to dominate the understory of a woodland. Wind-dispersed seeds allow it to disperse over long distances. When it is cut, this plant resprouts vigorously, making control difficult.


DOCUMENTATION NEEDS

Documentation required: Herbarium specimen or mounted snippet of the stem with flowers.
Best time for documentation: Late spring, summer.


ADDITIONAL INFORMATION

Integrated Taxonomic Information System (ITIS)
General taxonomic information

The PLANTS Database
Distribution information and additional links

Invasive Plant Council of New York State


REFERENCES

Fernald, M.L. 1950. Gray's Manual of Botany 8th ed. American Book Co., Boston.

Flora Europaea vol.3. T.G. Tutin, V.H. Heywood, N.A. Burges, D.H. Valentine, S.M. Walters and D.A. Webb ed. 1964. Cambridge University Press, Great Britain.

Gleason, H.A. and A.C. Cronquist. 1991. Manual of Vascular Plants of the Northeastern United States and Adjacent Canada. 2nd ed. New York Botanical Garden, Bronx, New York.

Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual. New York Botanical Garden, Bronx, New York. 

Lauvanger, E.G. and L. Borgen. 1998.  The Identity Of Vincetoxicum In Norway.   Nordic Journal Of Botany  18 (3): 353-364.

Sheeley, S.E., and D.J.Raynal.  1996.  The Distribution And Status Of Species Of Vincetoxicum In Eastern North America.  Bulletin Of The Torrey Botanical Club 123 (2): 148-156.