Cynanchum laeve is a vining perennial herb native to eastern and central U.S. states and Ontario. Common names include sand vine, honeyvine, honeyvine milkweed, bluevine milkweed, climbing milkweed, and smooth swallow-wort. The root system of C. laeve can cause it to be very difficult to eradicate, especially in agricultural fields. It is a larval food of monarch butterflies and milkweed tussock moth larvae. C. laeve can cause eye irritation if touched and can be toxic to humans and livestock if ...