Dioscorea bulbifera aka Air Potato

Dioscorea bulbifera is a perennial vine in the yam family. Its common names include air potato and aerial yam. It comes from tropical and subtropical parts of the Old World. Its range includes Africa, southern Asia, and northern Australia. Growers raise it in tropical regions for its aerial tubers. It also grows wild and has spread beyond its native range.

The vine grows from a woody rootstock with tubers. Its stems reach about 33 feet [10 metres] in cultivation. North Carolina State reports lengths reaching 70 feet [21.3 metres]. Growth is fast and can reach eight inches a day. The thick, smooth, green stems twist around nearby plants. They may also trail across the ground. Winter kills back the stems where conditions turn cold. Surviving tubers send up new growth in spring.

The green leaves grow one at a time along each stem. Each has a heart-shaped base and a sharp tip. Leaves measure about 0.2–0.8 feet [0.05–0.25 metres] long. Their edges are smooth, and veins spread from the base. These veins give the leaf surface a puckered look. Aerial tubers, called bulbils, form where leaves join the stems. Some are smooth and tan; others are rough and brown. Their size ranges from a pea to a grapefruit. Even small bulbils can sprout and spread the vine.

Flowers are rare in the United States and appear in fall. The small greenish-white blooms grow in clusters beside the leaves. Reports from Florida record only female plants. When flowers receive pollen, they can form capsules with partly winged seeds. These capsules differ from the much larger bulbils. In the United States, tubers drive most of its spread.

The plant needs sun and warm conditions for good growth. It favours deep sandy loam that drains well but stays moist. Waterlogged soil does not suit it. A dry season lasting two to three months suits its growth cycle. PFAF lists USDA zones 9–12, but also reports marked cold sensitivity. Temperatures of 9°C or lower can kill it. Its rapid spread can smother native plants in Florida. North Carolina State advises against planting this invasive vine. It reports no major pest or disease problems. Florida has released Lilioceris cheni beetles to help control it.

Food use needs care because the aerial tubers contain toxic alkaloids. PFAF records cooked aerial tubers and roots as food. It also records use of the flower clusters as food. Wild plants are poisonous raw, and toxin levels vary. The sources describe thorough cooking to break down these toxins. They also record traditional use for wounds and skin complaints. Those records do not establish that home remedies are safe.