Lesser Yam /Dioscorea Esculenta/
Lesser Yam is a perennial, climbing plant producing annual stems about 3m long from a tuberous rootstock.
A staple food, it is often cultivated in tropical areas, especially Asia and the Pacific, for its edible root.
Edible species of Dioscorea have opposite leaves whilst poisonous species have alternate leaves.
The tubers are oval, up to 20cm long and 6-8cm in diameters and hairy. Each plant can produce 5 to 20 tubers. The flesh is yellow or white and average around 250g, though larger ones can weight over 1kg.
Sweet and pleasant, with a flavour somewhat like sweet potato or chestnuts. Can be boiled, baked or fried just like potatoes.
This species will grow in drier climates than other yams, so long as the rainfall is evenly distributed through the year.
This 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.
Succeeds in full sun and also in light shade
For best yields, this species requires a deep, well-drained, fertile soil that is not liable to waterlogging.
Can grow in sandy or poor gravelly soils as long as enriched with organic matter.
Crop takes 7 – 10 months to mature.
An improved yield if grown on a trellis and the vine is tipped to keep growth under control, which encourages production of tubers.
Hilling the plant up also increases tuber size.
Tubers – cooked
They must be thoroughly cooked in order to destroy toxic alkaloids.
Pieces of tuber, each weighing around 50-80g with dormant buds, are planted in situ 4 – 8cm deep.
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.
The larger the piece of tuber used for propagation the larger and more productive the plant will be.
If the plant is happy, it’ll produce offshoots and you can propagate from those. When the plant is mature, it will produce a flower, again in Spring, which sprouts directly from the soil.
Risks and weed potential
Harvesting & Processing
Harvest mature tubers for storage in Winter when plant growth has stopped and the leaves begin to yellow.
When harvesting, dig away from the tubers to avoid injury to the tuber. Tubers are easily bruised and will rot if damaged.
Tubers can also be harvested early for eating from 5 months.
This is called ‘bandicooting’.
Dig and carefully remove a tuber or two. The plant will continue to grow and produce until the plant becomes dormant.
Whole undamaged yams can be stored for several months.
After harvest cure tubers in the shade until dry.
Store in a well ventilated dry cool building.
If tubers stored for eating, sprout in storage rub off the sprouts.