Plant of the Month
Black Swallow-wort
Black Swallow-wort (Cyananchum louiseae; previously Vincetoxicum nigrum and Cynanchum nigrum) is a European native, which is one of our most aggressive alien plants, forming extensive patches that crowd out native vegetation. When it moves into an area, it covers old fields of grasses and goldenrods, changing their structure and destroying biodiversity. It also grows along dry edges of riparian areas, suffocating native plants as it has on the banks of the Connecticut River Valley in Vermont.
Because this plant is a member of the milkweed family, monarch butterflies are known to lay their eggs on it. Unfortunately, the chemistry is wrong for the larvae and they do not survive.
The profusion of twisted vines formed by Black Swallow-wort have led to the nick-name of "dog strangler," although there are no known cases of dogs actually being trapped by the plant.
Watch for this plant in your area. If you see it, contact your local Conservation District. Early detection and rapid response is critical in dealing with Black Swallow-wort, and its closely related cousin, Pale Swallow-wort (Cyananchum rossicum)
Plant of the Month Archives
December 2008 - Witch Hazel
January 2009 - Winterberry
March 2009 - Desert Ironwood
April 2009 - Marsh Marigold
May 2009 - Serviceberry
June 2009 - Choke Cherry
July 2009 - Northern Bush Honeysuckle
August 2009 - Butterfly-weed
September 2009 - Firecracker bush
October 2009 - Black Swallow-wort