Dioscorea polystachya (batatas) – Chinese Yam; Air Potato

General Information: A twining perennial vine in the Sweet Potato family. Also known as Dioscorea batatas and by some sources (incorrectly) as D. opposita or D. oppositifolia. Tendrils emerge from an underground tuber in Spring. By autumn, mature vines develop numerous aerial tubers where the leaves meet the stems. These tubers, known as bulbils, resemble miniature Potatoes in flavor and appearance. In ideal settings, these vines can be comparable in yeilds, per acre, as Potato fields! The hardy vines handle pruning quite well, as the plants store lots of energy in the tubers. The aerial tubers have a long shelf life. As an experiment, one of our employees left some on a windowsill all winter long at room temperature and planted them in spring. Nearly 80% of them sprouted! In addition to edible qualities, these plants also have numerous uses in Traditional Chinese Medicine, as an ingredient in natural cosmetics, and in the Biodynamic Farming approach developed by Rudolf Steiner.

Edible Qualities: The highly nutritious aerial tubers are edible fresh or cooked. They have a rather starchy and somewhat mucilaginous texture raw, becoming much more palatable when cooked. Useful and versatile with the same exact flavor profile and texture as regular Potatoes. Widely used in East Asian cuisine. The tubers can be collected at any time after they turn brown. Tubers which have fallen off the vines can be collected and eaten at any point throughout the winter and early spring. Fallen tubers with new shoots can even be eaten with the shoots removed. Mature tubers can also be dug up and eaten. These can become massive, the largest being reportedly up to 10 pounds and growing 3 feet down in the soil!

Cultivation Details: An excellent high-yielding plant for balconies and urban gardens. Plant along a fence or trellis. Plants may be kept in pots or specialized raised beds to better access the underground tubers as they mature. Vines should be trained to grow where the bulbils can be easily reached. Bulbils should be collected diligently, as those which fall to the ground or become buried will readily re-sprout the following year. Vines which grow into trees or bushes are difficult to access. Like most members of the Yam Family, this plant is dioecious, meaning that male and female flowers are borne on separate plants. The plant is not known to reproduce via seed in the US and instead spreads when bulbils are dispersed. The flowers, especially of male plants, are Cinnamon scented, which is where the occasionally used common name “Cinnamon Vine” comes from.

Control Methods: The best method of control with this plant is to eat them! Site planning is very important with this plant, as they grow rapidly. The cut vines should not be composted, as they can take root and spread in a compost pile. For complete control, dig up mature tubers in spring every 2-3 years, before they get very large, and replace them with sprouted bulbils if desired. The best time to scout for and remove sprouted bulbils is from mid May to mid June. Unwanted portions of this plant should be boiled before discarding or burned. It is not advisable to plant this species in or near forested areas, as they can easily out-compete native species. Growers faced with an overgrowth of these plants may consider researching sources for Air Potato Beetles, which will completely devour and control these plants.

Growing Requirements: Plant in full sun to nearly full shade. Plants grown in shadier conditions grow more slowly, with only slightly lower yields. Tolerant of most soil types. Underground tubers in heavy clay soils are more difficult to access. Prefers moist, well-drained soils. Suitable for acidic, neutral, or mildly alkaline soils.