Arial yam, potato yam, air potato /Dioscorea. Bulbifer/
Aerial Yam is a perennial climbing plant producing annual stems up to 10m long from a woody, tuberous rootstock.
It has the familiar heart shaped leaves of other Dioscorea but the leaves are alternate on the rounded stem and the stem twines to the left.
The Aerial Yam produces aerial tubers from leaf axils along the stem.
These potato-sized bulbils are prolific and much easier to grow and to harvest than potatoes in the subtropics.
The tubers are produced, and can be harvested, over a long period of time.
The best varieties tend to have an angular flattened shape, smooth skin and a skin color, which evokes the name ‘turkey liver yam’.
They weigh up to 2kg but an average weight is about 0.5kg.
The flesh can be purple, pale yellow to near white.
Plants often need to be grown for two seasons in order to produce full-size aerial bulbs.
The more aerial bulbils the plant produces the less edible the underground tuber. Highly productive varieties have a woody root system, which is not edible.
Aerial yam can be boiled, baked or fried, just like potatoes.
Yam is a perennial but is most often harvested and replanted annually.
Day length of more than 12 hours is preferred during the early growing season (late Spring to early Summer) since this encourages vegetative growth. Day lengths of less than 12 hours towards the end of the growing season (late Summer to Winter) will encourage tuber formation and development.
The vines die back in Winter and the tubers become dormant. They reshoot and resume growth with the first rain after the soil warms up in Spring.
It prefers a well-defined dry season of 2-3 months
For best results grow in fertile soil with plenty of organic matter.
Is drought tolerant and requires excellent drainage and does not tolerate water logging.
Grow on a strong trellis no taller than you can reach so you can easily harvest the bulbils.
Plant at least 1m apart.
Aerial tubers – cooked
They must be thoroughly cooked in order to destroy toxic alkaloids.
Cuttings of tubers. Small root tubers can be cut into sections. Each section should have 2-3 dormant buds. The cut tuber is dipped in wood ash and left to heal for several hours to promote wound healing and reduce the risk of fungal infection.
Aerial bulbils can also be planted and these produce vigorous plants
The aerial bulbils can be divided into two or more equal sized pieces.
The larger the piece of tuber used for propagation, the larger and more productive the plant will be.
Risks and weed potential
As every leaf has the potential to produce a bulbil, this plant has pest potential and has naturalized in warm climates. Do not allow it to grow on trees as bulbils will fall from the vine and grow. Instead, grow on a small trellis and harvest every bulbil and only share with others who will responsibly manage this valuable plant.
Harvesting & Processing
The bulbils are produced in 5-6 months from planting, though some forms can produce a crop in as little as 3 months.
Harvest as you need them or when they fall off the plant at a slight touch.
Whole unblemished bulbils can be stored in a cool dry place until they start to shoot in late Spring.
If tubers stored for eating start to sprout in storage, rub off the sprouts.