This is Cynanchum laeve, also known as Sand Vine, Honey Vine, Blue Vined Milkweed, and Honeyvine Milkweed. If the Monarchs and Queens could vote, this plant would be at the top of the list. Many people claim that the Monarchs prefer the sand vine in their yard over the Asclepias. This is a larval host plant of the Monarch and Queen butterflies, and it is just a hit with all nectar gatherers. This plant likes to live in mostly sun to partial shade and blooms from the middle of the Summer until the early Fall. This is an aggressive plant so put it somewhere you can keep it in check. It is well worth it just for all of the wildlife that flocks to it. USDA Hardiness Zones 4 to 9.