Cynanchum nigrum - Black Swallowwort

Image of flowers of C. nigrum Image of fruit of Cynanchum nigrum
Flowers of Black Swallowwort Close-Up of developing fruit

Close-Up of developing fruit
(Photo by J. Forman-may not be used w/o permission)

Animated Image of the Occurrences of Cynanchum nigrum Over Time
(Whatdoes this image mean?)
Cynanchum nigrum, also known by the name Vincetoxicum nigrum,is in the same family as the more commonly known Milkweeds:  the Asclepiadaceae. Unlike most other species in this family, Black Swallowwort grows by clinging,climbing vines, and its other common name, Dog-Strangling Vine, is in obviousreference to this habit.  This plant species was apparently firstgrown in Massachusetts as an ornamental, and subsequently escaped fromcultivation (FOBD1907-24). Even today it can be seen growing along fences in urban andsuburban areas.

Gleason and Cronquist (1991) list thisspecies as having escaped from cultivation in the northeastern United States,brought here from southern Europe.  As you can see from the animatedmap above, C. nigrum was already established in several Massachusettscounties by the early 1900's.  Williams (1902) recorded this speciesas present in three New England states (Vermont, Rhode Island and Massachusetts)by the turn of the 20th century.  While this European native is notcurrently given much attention in the state of Massachusetts, it is consideredan invasive species in other areas of North America, including Ontario(Miller1994) and New York.


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