Honeyvine Milkweed (Ampelamus albidus or Cynanchum laeve) is a true milkweed species and, therefore, a host for Monarch butterfly larvae. But having this twining plant in your garden is not a good idea. Also known as bluevine, climbing milkweed, dog’s-collar, Enslen’s vine, peavine, sandvine, smooth anglepod, or smooth swallow-wort, honeyvine milkweed is aggressive and invasive. Once the plant has bloomed and produced seeds, your property will forever have this vine. Many state extension sites list honeyvine milkweed as a serious pest in field crops, and a nuisance in smaller scale no-till gardens.
The plant is a North American native with a strong distribution in the eastern half of the U.S. It prefers moist, fertile soil, but will tolerate most any type. In the wild, this weed is found in fencerows, thickets, cultivated fields, and along riverbanks, but mostly in any disturbed habitat. Flowering is from June through September, with a single plant able to produce up to 50 seed pods containing numerous seeds.
Honeyvine milkweed is often confused with field bindweed (Convolvulus arvensis), hedge bindweed (Calystegia sepium), wild buckwheat (Polygonum convolvulus), and several species of morning glory (Ipomoea spp.). Distinguishing features that identify honeyvine milkweed are the leaves and flowers. Leaves are 3 to 7 inches long and opposite, smooth and shaped like a stretched heart, and colored a deep green with white veins. Honeyvine flowers are small and white in clusters. The “look-alikes” mentioned above have either inconspicuous flowers (wild buckwheat) or funnel-shaped flowers.
This weed is difficult to eradicate once it takes over. The roots are deep and fibrous, and usually break when trying to pull or dig. Reproduction is by both seed and spreading roots. The vine effectively buries itself in the central portion of a shrub or plant and seems to almost secretly work its way to the top; length of these vines can be from 10 to 30 feet. Seed pods are produced at the tips of the vines, so if one gets into a tall shrub, you might not even see the pods until it’s too late.
Pods are 3 to 6 inches in length, smooth green, and paired. Removing the pods at this stage is one method of controlling the spread by seed. If pods are too high to reach, simply cut the vine at the base, but be sure to do it while the pods are green. Once the pods have matured and turned dark, they are tricky to handle. Inside the pods are dozens of flat, horse-shoe shaped seeds with feathery appendages. If the pod bursts, the wind carries the seeds away to start the cycle again. Another method for circumventing the spread of seed is to tie a plastic bag around the seed pods before cutting the vine. That way, if the pod continues to dry, the seeds won’t escape. The best method of control once this pest invades is to check landscape beds every other day for newly emerging vines. At that stage, they are quite easy to pull.
Honeyvine has no known toxicity, and none of the literature mentioned medicinal uses for the plant, other than in China (a different species).