About Cynanchum laeve (Michx.) Pers.
Cynanchum laeve (Michx.) Pers. is a twining vine with heart-shaped leaves, most commonly found growing along roadsides, fence rows, fields, and other disturbed areas. As a member of the Apocynaceae family, it is easily identifiable by its opposite leaves, milky sap, and distinctive flowers and follicles, also called "milkweed pods". Its seeds are dispersed by wind and can travel long distances, and a single C. laeve plant can produce up to 50 follicles. It has a fleshy, brittle root system made up of a large taproot and additional lateral roots, which can grow as deep as 6 feet. Newly developing stems are light pink, and will produce milky sap when broken. Its Vase-shaped flowers, which grow in clusters on short stalks, have 5 white petals, and C. laeve blooms from June through September. Cynanchum laeve is distributed across the eastern and central United States and Ontario, Canada. It can be found in wetland areas in the arid West, Atlantic and Gulf Coastal Plain, Eastern mountain and Piedmont, the Great Plains, Midwest, and the North Central and North Eastern United States. It typically grows in disturbed habitats including thickets, low moist fields, riverbanks, fence rows, and cultivated fields. This species acts as a food plant for monarch butterfly caterpillars. It is also consumed by larvae of the milkweed tussock moth, Euchaetes egle, across both the Eastern and Western United States; these moth larvae feed on C. laeve and other plants during their development. Cynanchum laeve is not edible for humans. Its sap can cause eye irritation and damage mucous membranes, and consuming large quantities of the plant is toxic to humans. Thorough hand washing is recommended after handling this plant. Hay fed to livestock may contain C. laeve, which can be toxic to livestock when consumed in large amounts. Most animals avoid eating C. laeve due to its bitter taste. The US Fish and Wildlife Service recommends taking precautionary measures for this plant: do not graze hungry animals in pastures that contain C. laeve, eradicate the plant from driveways and trails, and closely monitor livestock that have just been moved into areas where C. laeve grows. Because of its deep, extensive root system, C. laeve can be very difficult to eradicate from agricultural fields. As a climbing vine that grows over other plants, it also creates complications during crop harvesting.
