Air-potato

Dioscorea bulbifera
Family: Dioscoreaceae

Natural History
Air-potato with aerial tubers growing up a tree
Photo credit: Larry Korhnak, University of Florida

Air-potato (also called potato-yam, air-yam, Chinese-potato or devil's-potato) is a member of the family Dioscoreaceae (yams). They were introduced from Africa in the early 1900's as an edible landscape plant. The tubers may be cultivated as a starchy food source, but are generally bitter when grown wild.

The vines are extremely aggressive and grow into dense masses that quickly out-compete native vegetation. They often climb high into the canopy and over-top even the tallest trees. The prolific aerial tubers help the plant to spread quickly. Even though the vines and aerial tubers are deciduous and lie dormant for the winter months, the underground tubers may still sprout and continue the spread of the plants year-round. These vines are often seen climbing into the foliage along forest edges or even in urban settings. They pose a serious threat to forested habitats.

Chemical compounds are extracted from the plants to produce steroids and birth control pills. West African tribes grow air-yams as an important food plant. The tubers, which are said to have a potato-like flavor, are boiled twice before eating, to remove any toxins and bitterness.

Air-potato is similar to the native species, wild yam (Dioscorea floridana), which has shorter leaf blades and no aerial tubers. It also resembles winged yam (Dioscorea alata), which has opposite leaves and winged stems.

Air-potato is currently found in 23 counties in Florida and is still spreading. Many cities, including Gainesville, have held wintertime "air potato roundups" to collect and destroy any tubers found on the ground in natural areas, but the events have had little impact on the tubers that are already underground. Recently, however, a leaf-feeding beetle, Lilioceris cheni, was introduced into Florida from China for biological control of air potato. Extensive testing has shown that the beetle only consumes the leaves of air potato and will not damage any other plants. By devouring the green leaves on the air-potato vines, the beetle prevents photosynthesis and forces the plant to exhaust its underground energy reserves. Early results from the release are very positive and suggest that the beetles may succeed in controlling or even eliminating this weed.


 

Identifying Characteristics

Habitat: Air-potato grows aggressively in a variety of habitats, from pine flatwoods to hardwood hammocks, forest edges and roadsides. It will grow in both disturbed and undisturbed soils.
Size/Form: The plant is a twining, deciduous vine that grows 60 - 70' long. It branches out in all directions as it grows and it produces aerial tubers, or bulbils, which appear along the stem and have a potato-like appearance. The bulbils generally range from marble-sized to tennis-ball-sized, but they can occasionally be much larger. When freezing weather in the wintertime kills the above-ground portion of the plant, the bulbils drop to the ground where they eventually sprout in the springtime to form new vines.
Leaves: The leaves are large, about 8" long, simple and alternately-arranged. They are broadly heart-shaped (cordate) and have rounded leaf bases and long petioles. The leaves have obvious, deep venation (rugose veins). The leaf margin is smooth.
Flowers: Flowers are rare, appearing in panicles or spikes to 4 in long.
Fruit: The fruit, which is also rare, is a small capsule, with partially-winged seeds.

 

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