Honeyvine Milkweed (Cynanchum laeve)
Milkweed Family (Asclepiadaceae)
Ampelamus albidus, Gonolobus laevis, bluevine, climbing milkweed, dog's-collar, Enslen's-vine, honeyvine, honeyvine swallwort, peavine, sandvine, smooth anglepod, smooth swallow-wort.
Origin and Distribution:
Honeyvine milkweed is a native species of North America. It is currently distributed throughout the eastern half of the U.S. In Ohio, honeyvine milkweed is abundant in most southern and some central counties and it is scarce in the north. The weed is usually found in cultivated fields, fencerows, thickets, low moist woods, along riverbanks, and other disturbed habitats. It prefers fertile, moist soil.
Honeyvine milkweed is a twining perennial vine. Characteristics distinguishing it from other perennial vines include opposite (2 leaves per node), heart-shaped leaves and whitish, vase-shaped flowers that form in axillary clusters. Also, foliage exudes a cloudy sap if crushed or cut. The plant reproduces by seeds and horizontal spreading roots.
The root system consists of a deep vertical taproot and many lateral roots. Roots are fleshy and brittle.
Seedlings and Shoots:
Young stems are often pink-tinged and the surface of young leaves is shiny. Young plants exude a faintly cloudy sap when cut, crushed, or broken.
The viney stems are smooth, slender, twining, usually climbing but sometimes trailing, and up to 20 feet long.
Leaves are opposite (2 leaves per node), 3 to 7 inches long, deep green, smooth, waxy, and thin. Leaves have deep, heart-shaped bases and elongated, pointed tips. They attach to the stem by way of long, slender leaf stalks (petioles).
Flowers, which consist of 5, whitish, upright petals that are about 1/4 inch long, are vase-shaped and arise at leaf axils in clusters on short stalks.
Fruits and Seeds:
Seed pods are 3 to 6 inches long, smooth, green, and usually paired. Pods split open along one side when mature releasing numerous seeds. Seeds are brown, oval, flattened, horseshoe-shaped, and have a tuft of silky-white hair attached to one end.
The perennial vines field bindweed (Convolvulus arvensis) and hedge bindweed (Calystegia sepium), and the annual vine wild buckwheat (Polygonum convolvulus) may be distinguished from honeyvine milkweed by leaf and flower shape. The leaves of the bindweeds and buckwheat are more arrow-shaped. Bindweed flowers are funnel-shaped, while those of wild buckwheat are inconspicous. Annual and perennial morningglory species (Ipomoea spp.), including bigroot morningglory (Ipomoea pandurata), often have heart-shaped leaves and may also resemble honeyvine milkweed. However, morningglory species have funnel-shaped flowers. The seed pods of common milkweed (Asclepias syriaca), an upright perennial, are similar to those of honeyvine milkweed, but have soft, spine-like projections.
Flowering occurs between June and September. Each honeyvine milkweed plant can produce up to 50 pods. Roots often grow 6 feet deep. The twining, climbing habit of this species can cause serious problems during crop harvest. Systemic herbicides should be used for best control.