If I were a pirate, my ship would be named "The Black Swallow-wort." That would strike just the right notes of romance and terror, as indeed does the namesake invasive species that inspires this selection. I can just see the customized Jolly Roger at the masthead, tendrils of Monarch Caterpillar killing bindweed coiling from grinning skull sockets and clove-hitched around the crossed bones. Its other name is Dog-strangle vine, which while evocative sounds more like a more appropriate appellation for one of my scurvy crew.
An infestation of Cynanchum louiseae, like Syphilis, is one of those conditions you really don't want to catch. Its polyembryonic seeds are wind dispersed and will also float downstream to new destinations. It is easily confused with a near relative Pale swallow-wort (Cynanchum rossicum), likewise invasive, and to make matters more taxonomically confusing has also been described as an entirely different genus Vincetoxicum nigrum. No matter what label it gets in the herbarium, it is villainous as an invasive plant.
A European species introduced in the late 1800s, Black swallow-wort has expanded rapidly in a variety of habitats from Canada to Missouri and especially along the Atlantic coast. Monhegan Island is enduring a dramatic infestation, from the rocky crevasses just above the spray zone by the sea cliffs to the forest understorey and meadows around the village. A forest health study conducted on the island found that Black swallow-wort and Asiatic bittersweet (Celastrus orbiculatus) were rapidly invading areas where control efforts were underway for another invasive, Japanese barberry (Berberis thungbergii).
Blackswallow-wort is a management nightmare, for it resprouts when cut as well as from root fragments and can form matted monocultures that overwhelm native species. It is also hell on Monarch butterfly larvae. A relative of milkweed, it proves a confusing and toxic larval host.
Islands, especially small, isolated ones, suffer the greatest harm from exotic introductions, and while barberry is a bear and bittersweet a known thug, I would consider the Black Swallow-wort invasion on Monhegan a greater threat. It is well underway and eradication can no longer be hoped for. Vigilance, containment and rapid response to new outbreaks are the best hope, but this is not something an Island of 70 or so full-time residents can do one their own with volunteer labor. The rest of us who visit and enjoy this place need to do our part.
Once I started looking for it I found it everywhere. I found some growing at the base of the path leading to the Upper Cottage on Monhegan and lost no time in pulling it up and exposing its roots to dessication. There's a nice cluster of spearmint there in great demand for Mojitos and a great patch of wild strawberries that would be sorely missed in pancakes if swallowed by Swallow-wort. Charity, indeed, begins at home, and pirates belong in sea stories, not ravaging our coasts with Dog-strangle vine.