LCT Vice President and invasive species management advocate Rick Findlay spotted Black Swallow Wort in Littleton recently and is asking for your help in spotting and eliminating this invasive plant species before it can spread its airborne seeds.
Black or Louis’ swallow-wort (previously Vincetoxicum nigrum and Cynanchum nigrum) is a perennial, twining herbaceous vine. The leaves are oval shaped with pointed tips, 3-4 in. long by 2-3 in. wide, and occur in pairs along the stem. The small five-petaled star shaped flowers are dark purple to almost black with white hairs, about ¼ in. across, and are borne in clusters. The fruits are slender tapered pods, 2 to 3 in. long by about ¼ in. wide, turning from green to light brown as they mature. Plants have rhizomes (underground stems) that sprout new plants and grow in clumps which can form extensive patches.
Remove pod-bearing plants from the site and destroy them. Eradication on a small scale must be very thorough and requires dedication. The complete root crown must be dug out before the seeds ripen.
Collect and bag plants bearing seeds and dispose of them in heavy garbage bags. Infested land might be brought under control by plowing and planting an annual crop until the seed soil bank is depleted, possibly as long as five years.