Dog-strangling Vine Cynanchum nigrum
Family: Apocynaceae (Dogbane/Milkweed)
Branching: Opposite
Other names: Swallowwort, Vincetoxicum nigrum

Dog-strangling Vine is a member of the Milkweed family, and is not actually a woody plant.  It has been introduced from Europe and Asia and has become a serious invasive problem in many areas.  Its non-woody growth and often retained seed pods can help in winter identification.  Though technically opposite, most of what remains to be seen in the winter regarding the fruit capsules appears alternate.  There is much confusion regarding the names of Dog-strangling Vine.  The common name Swallowwort is often used, and three varieties or species are sometimes listed: Black, Pale and White.  The two genus names, Cynanchum and Vincetoxicum are used almost interchangeably with various species names nigrumrossicum, vincetoxicum.  Overall, there is much contradiction between many sources, especially online.

Remnants of the fruit capsules of Dog-strangling Vine

The fruit capsules are typical of other members of the Milkweed family

Another view of the vine and capsules

Another view of the vine.  After the seeds have blown away, the shell of the capsule can still remain, resembling a tried blade of grass

Outer shell of the fruit capsule

Dog-strangling Vine strangling a Common Buckthorn

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copyright 2008 Josh Sayers
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