Invasive Plants of Wisconsin

Vincetoxicum nigrum (L.) Moench.
black swallow-wort
Family: Asclepiadaceae
plants plants leaves leaves roots flower flower fruit
live plant live plant leaves lower leaves below-ground portions flowers flower fruit

Vincetoxicum nigrum is an herbaceous plant, erect when young and sometimes becoming a vine as it matures. Leaves are simple and opposite, the upper ovate to lanceolate and the lower sometimes broader as shown above. Young plants and those growing in the open may not be initially recognized as a vine, although they tend to twine around one another even when growing erect. When growing in company of trees and shrubs they are more likely to reveal the viney habit. Below-ground there are spreading whitish roots and numerous buds, capable of generating new stems. The flowers are very small and dark and easy to overlook. The fruit is a follicle, splitting open along one side at maturity to release wind-borne seeds, similar to the familiar milkweed "pods".

This is a new invasive in this area and the following information on control is from the literature. Pulling the plants is generally not successful, since some portions are left below-ground and readily re-sprout. Similarly, cutting or breaking off the tops of the plants is not effective, though it can be effective in reducing the nunmber of seeds produced. Control methods have not been well-developed for this species in our region, but glyphosate ("Roundup" and others) has been reported as effective elswhere. It is reported to be very difficult to control if well-established, so workers would be well-advised to be alert to its arrival and to exert maximum effort immediately to save much work later on.



known Wisconsin distribution


Contact the author