Dioscorea villosa aka Wild Yam

Dioscorea villosa, or wild yam, belongs to the yam family. This vine lives for years. It grows from thin rhizomes, or stems beneath the soil. Its native range starts in southern Ontario. It spans the central and eastern United States. It grows in woods, thickets, and at woodland edges. It also grows near streams, marshes, roads, and fences. Its stems reach 3–18 feet [0.9–5.5 metres] long. They climb by twining around nearby plants or other supports.

The thin stems are smooth and round in cross-section. They range from pale green and yellow to red. The heart-shaped leaves are simple, not split into leaflets. They have smooth edges and palmate veins that spread like fingers. Most leaves grow in turn along the stem. Near the base, they may grow in pairs or whorls. Whorls are rings of leaves around the stem. The smooth upper sides are medium green. Fine hairs coat the paler undersides. The amount of hair varies. New leaves have a gold-green tint. Long leaf stalks range from green to dark red.

Small flowers open from April through July. They have a greenish-yellow hue. Each plant bears male flowers or female flowers, not both. Male flowers hang in branched groups called panicles. These grow from leaf axils, where leaves join the stem. Female flowers form drooping groups called racemes. Each has a large ovary, the part that forms fruit. Each flower has six tepals. Both sexes must grow together to make seeds. Female plants form capsules with three cells and flat, winged seeds. The fruits show from September through November. They turn from golden green to tan as winter comes. Their dry walls turn papery, and wind spreads the seeds.

Grow wild yam in sun or partial shade. It prefers rich, light soil that drains well. Sandy soil and loam both suit it. It accepts neutral to alkaline soil and some dry spells. North Carolina State lists USDA hardiness zones 6–9. Plants For A Future reports survival down to about −15°C. This vine needs little care. It suits native plantings and woodland gardens. Its leaves add texture. Its stems give birds and small animals cover and nesting sites. You can grow more plants by division, splitting an existing plant. Reports list no major insect pests or diseases.

Wild yam has a history of use as medicine. Its roots contain diosgenin, a raw material for making steroid drugs. This does not mean the roots are safe to eat. Sources disagree on their use as food. Plants For A Future lists cooked tubers with cautions. North Carolina State says the tubers are not edible. Reports of harm include kidney damage and vomiting. They also include other side effects. Plants For A Future also warns against use during pregnancy.