Lesser Yam

Lesser yam (Dioscorea esculenta), called choti zamin kand in some Pakistani markets and known regionally as Asiatic yam, is a twining tuberous vine with clusters of small brown tubers that cook up like a mild, drier potato. POWO records the species as native across tropical Asia from the Western Himalaya to the Philippines, now widely cultivated through South-East Asia, Oceania, and the Caribbean.¹ For a Sindh coastal plot or a humid pocket of southern Punjab it offers an underused starch crop that fruits underground while the climbing vine reuses vertical space already given to a stake or fence.

Where it thrives

Lesser yam is a warm, wet-season crop. PROSEA records optimal annual rainfall of 875 to 1,750 mm, a minimum temperature of about 23 degrees Celsius for active growth, and best yields on light, well-drained soils at pH 5.5 to 6.5.² It does not tolerate frost and resents heavy waterlogged clay. In Pakistan that places it firmly on the Sindh coast and the lower Punjab plains, in beds that drain freely after monsoon. Highland zones are too cool to ripen the tuber clusters within one season.

Role in the system

It is a secondary-stratum annual climber. The vine throws a slender twining stem 2 to 3 metres up a stake, pole, or living support, with heart-shaped leaves and spiny lower stems. Underground, it forms a tight cluster of 4 to 20 small tubers near the surface, which is unlike the deep single tuber of D. alata and far easier to harvest by hand. A review in Frontiers in Pharmacology on neglected and underutilised yams places D. esculenta among the species with the highest agro-economic potential for smallholder food security, especially where soil fertility is patchy.³

Growing it

Propagate from small whole seed tubers, planted on mounds or ridges at the start of the warm rains. PROSEA’s spacing standard is 100 cm between mounds and 50 cm within the row for sole cropping, with 2 to 3 manual weedings through the season and staking once the vine emerges.² Maturity runs 6 to 10 months; lift when the vine yellows and dies back. Keep handling gentle since the small tubers bruise. Save the smallest tubers as the next year’s seed and eat the larger fraction. A peer-reviewed nutritional appraisal of the Dioscorea genus notes the tubers store well underground for several weeks past maturity, which lets a smallholder harvest as needed rather than all at once.⁴

What you get

Yields on smallholder plots run 10 to 40 tonnes per hectare of fresh tuber, with documented peaks up to 70 t/ha under good management.² Tuber flesh is white, low in toxins compared with wild Dioscoreas, and good boiled, fried, or pounded into a stiff porridge. The dietary fibre and resistant-starch profile makes it a useful low-glycaemic substitute for potato in diabetic households.⁴

Sourcing notes

Seed tubers are the bottleneck. Source from a tropical-tuber specialist or via the Sri Lankan and South Indian seed networks rather than expecting local availability; once established, the crop self-perpetuates from saved seed tubers each season. Companion well with chilli, ginger, or pigeon pea, which uses the same warm-wet window and fixes nitrogen the yam will draw on.

Sources

1. Royal Botanic Gardens, Kew (2024). “Dioscorea esculenta (Lour.) Burkill.” Plants of the World Online.
2. Plant Resources of South-East Asia (PROSEA) (2018). “Dioscorea esculenta (PROSEA).” Pl@ntUse.
3. Padhan, B. & Panda, D. (2020). “Potential of Neglected and Underutilized Yams (Dioscorea spp.) for Improving Nutritional Security and Health Benefits.” Frontiers in Pharmacology.
4. Obidiegwu, J.E., Lyons, J.B. & Chilaka, C.A. (2020). “The Dioscorea Genus (Yam)—An Appraisal of Nutritional and Therapeutic Potentials.” Foods.