The invasive pale swallow-wort (Cynanchum rossicum) is causing alarm as its presence spells trouble for monarch butterflies and local ecosystems. With its toxic nature and rapid spread, this noxious weed poses a significant threat to both biodiversity and wildlife habitats.
Sporting oval to heart-shaped leaves that shimmer in shades of yellow and green, pale swallow-wort can grow up to 7 feet long. Its clusters of small, star-shaped flowers range from pale pink to reddish-brown, creating an alluring yet dangerous facade. Thriving in various conditions, from shade to sun and different soil types, this resilient plant takes root in disturbed areas such as fields, woodlands, and brushy regions.
Wind dispersal plays a crucial role in the plant's expansion, aiding in long-range seed distribution. Additionally, pale swallow-wort can spread through activities like mowing and soil tillage, which break up root pieces and transport them to new locations. Once established, the vine forms dense thickets, covering extensive areas and suffocating native vegetation. This encroachment disrupts ecosystems, leading to reduced species diversity and the loss of crucial wildlife habitats.
Of particular concern is the impact on monarch butterflies. While female monarchs may lay their eggs on pale swallow-wort due to its milkweed family affiliation, common milkweed remains their preferred choice. However, the displacement of common milkweed by pale swallow-wort diminishes ideal breeding grounds for monarchs. The plant's toxicity also poses risks to other insect larvae and potentially affects mammals, including livestock.
Originating from Russia and Ukraine, pale swallow-wort found its way to the United States as an ornamental plant in the late 1800s. Since then, it has established itself in several eastern and Midwestern states, as well as British Columbia, Ontario, and Quebec in Canada. Recent discoveries in Scott County, Minnesota, reveal reproducing populations that are spreading into adjacent areas, raising urgent concerns.
Minnesota has classified pale swallow-wort as a Prohibited-Eradicate Noxious Weed, mandating the destruction of all parts of the plant. Mowing is discouraged due to the risk of seed dispersal. Transportation, propagation, and sale of pale swallow-wort are strictly prohibited, with non-compliance potentially resulting in enforcement actions.
Efforts to curb the spread of this invasive plant are crucial for safeguarding the delicate balance of ecosystems and preserving the habitats essential for monarch butterflies and other native species. Awareness and swift action are vital in combating the encroachment of pale swallow-wort and protecting the biodiversity that sustains our environment.
Photo Credit: istock-herreid
Categories: Minnesota, General