Lesser yam (Dioscorea esculenta)

Lesser yam (Dioscorea esculenta) is a plant species in the family Dioscoreaceae. It is an annual, herbaceous, climbing vine that is covered in hairs and often features spines 2–4 cm long; in wild specimens, the roots may also be spiny. The stems are terete (cylindrical) and twine in a leftward (sinistrorse) direction; they are spiny near the base—with the number of spines decreasing toward the top—and do not produce bulbils.

The plant possesses a fibrous root system reaching depths of up to 100 cm. Between 4 and 18 tubers develop at a depth of 1.5–12.5 cm, connected to the corm by stolons measuring 5–50 cm in length. Mature tubers are cylindrical—sometimes lobed—reaching 8–20 cm in length and 2–5 cm in width, with a thin, brown or grayish-brown skin. The surface of the tuber is smooth and bears 10–408 fibrous roots, each approximately 1.74 cm long. The flesh of the tuber is white.

The leaves are arranged alternately and are simple in structure. They are cordate (heart-shaped), measuring 10–15 cm by 10–17–17 cm, with an acuminate (tapered) tip. Each leaf has 9–13 primary veins, while the secondary veins are arranged regularly but do not form a distinct, repeating pattern. The petiole (leaf stalk) is 1–1.5 times the length of the leaf blade and often features two prominent spines at its base.

The inflorescences are unisexual. Male inflorescences emerge singly from the axils of the upper leaves; they typically bear one flower at a time along the floral axis, with a total of 70 or more flowers. Female inflorescences are spike-like racemes that curve downward; they also emerge singly from the axils of the upper leaves and can reach 40 cm in length. The fruit is a capsule that curves backward, measuring 27 mm in length and 12 mm in width. The seeds are winged.

The tuber sprouts, followed by the development of strong, growing roots. Underground stolons emerge 2–4 months after planting, with the tips of these stolons eventually forming new tubers. Mycorrhizal associations assist in nutrient absorption. The plant undergoes senescence after 6–10 months. D. esculenta thrives in humid tropical regions with an annual rainfall of 875–1750 mm, temperatures between 22–35°C, elevations ranging from 0–900 meters, and a soil pH of 5.5–6.5.

This plant is a versatile, traditional tuber that can be prepared in various ways, serving as both a simple snack and a main course. When steamed, boiled, or roasted, the tuber develops a fluffy texture and a savory flavor. It can also be sliced and fried to create a crispy exterior, making for an ideal snack. Furthermore, the tuber is processed into a variety of food products, including flour, an ingredient for vegetable dishes, a rice substitute, and porridge.

Per 100 g, the tuber’s composition includes 70–80 g of water, 1.3–2.1 g of protein, 0.1–0.3 g of fat, 26–36 g of carbohydrates (comprising 25 g of starch and 1–11 g of sugar), 0.2–1.5 g of fiber, 0.5–1.2 g of ash, 0.017 mg of vitamin A, 0.08 mg of vitamin B1, 0.02 mg of vitamin B2, and 20.3 mg of vitamin C. The starch consists of amylopectin, with angular-shaped starch granules measuring 0.5–2.0 µm and a gelatinization temperature of 69.5–80.5°C. Its high sugar content imparts a sweet taste.

TAXON

Kingdom: Plantae
Phylum: Tracheophyta
Subphylum: Angiospermae
Class: Liliopsida
Order: Dioscoreales
Family: Dioscoreaceae
Genus: Dioscorea Plum. ex L. in Sp. Pl.: 1032 (1753)
Species: Dioscorea esculenta (Lour.) Burkill in Gard. Bull. Straits Settlem. 1: 396 (1917)

HOMOTYPIC SYNONYMS

Oncorhiza esculentus (Lour.) Pers. in Syn. Pl. 1: 374 (1805)
Oncus esculentus Lour. in Fl. Cochinch.: 194 (1790)

HETEROTYPIC SYNONYMS

Dioscorea aculeata Roxb. in Fl. Ind., ed. 1832. 3: 800 (1832)
Dioscorea aculeata var. spinosa (Prain) Roxb. ex Prain & Burkill in J. Proc. Asiat. Soc. Bengal 10: 20 (1914)
Dioscorea esculenta var. fasciculata (Roxb.) Prain & Burkill (1914)
Dioscorea esculenta var. fulvidotomentosa R.Knuth in H.G.A.Engler (ed.), Pflanzenr., IV, 43(Heft 87): 190 (1924)
Dioscorea esculenta var. spinosa (Prain) R.Knuth (1924)
Dioscorea esculenta var. tiliifolia (Kunth) Fosberg & Sachet in Micronesica 20: 135 (1978)
Dioscorea fasciculata Roxb. (1832)
Dioscorea fasciculata var. spinosa Prain in Bengal Pl. 2: 1066 (1903)
Dioscorea papillaris Blanco in Fl. Filip.: 801 (1837)
Dioscorea papuana Warb. in Bot. Jahrb. Syst. 13: 273 (1891)
Dioscorea spinosa Roxb. ex Hook.f. in Fl. Brit. India 6: 291 (1892)
Dioscorea tiliifolia Kunth in Enum. Pl. 5: 401 (1850)
Dioscorea tugui Blanco (1837)

PUBLICATIONS

Baksh-Comeau, Y., Maharaj, S.S., Adams, C.D., Harris, S.A., Filer, D.L. & Hawthorne, W.D. (2016). An annotated checklist of the vascular plants of Trinidad and Tobago with analysis of vegetation types and botanical 'hotspots'. Phytotaxa 250: 1-431.

Bhattacharya, R.P., Pal, D.C. & Pati, B.R. (2014). A sytematic census of monocot climbers of Bihar anf Jharkhand states. Indian Journal of Forestry 37: 317-324.

Govaerts, R. (2000). World Checklist of Seed Plants Database in ACCESS Genera starting with letter D: 1-30141.

Govaerts, R., Wilkin, P. & Saunders, R.M.K. (2007). World Checklist of Dioscoreales. Yams and their allies: 1-65. The Board of Trustees of the Royal Botanic Gardens, Kew.

Hang, Y.Y. (2020). Dioscoreaceae in China : color-illustrated Chinese and English bilingual edition: 1-476. Jiangsu Phoenix Science and Technology Press.

Iwatsuki, K., Boufford, D.E. & Ohba, H. (2016). Flora of Japan IVb: 1-335. Kodansha Ltd., Tokyo.

Kotiya, A., Solanki, Y. & Reddy, G.V. (2020). Flora of Rajasthan: 1-769. Rajasthan state biodiversity board.

López Patiño, E.J., Szeszko, D.R., Rascala Pérez, J. & Beltrán Retis, A.S. (2012). The flora of the Tenacingo-Malinalco-Zumpahuacán protected natural area, state of Mexico, Mexico. Harvard Papers in Botany 17: 65-167.

Morat, P. & Veillon, J.-M. (1985). Contributions à la conaissance de la végétation et de la flore de Wallis et Futuna. Bulletin du Muséum National d'Histoire Naturelle. Section B, Adansonia 7: 259-329.

Nurtjahya, E. & al. (2026). Flowering Plants of Bangka Island: Native and Introduced. Acta Botanica Hungarica 68: 127-156.

Pandey, R.P. & Dilwakar, P.G. (2008). An integrated check-list flora of Andaman and Nicobar islands, India. Journal of Economic and Taxonomic Botany 32: 403-500.

Rahman, M.O. (2004). Second list of angiospermic taxa of Bangladesh not included in Hooker's 'Flora of British India' and Prain's 'Bengal Plants': series I. Bangladesh Journal of Plant Taxonomy 11: 77-82.

Samanta, A.K. (2006). The genus Dioscorea L. in Darjeeling and Sikkim Himalayas - a census. Journal of Economic and Taxonomic Botany 30: 555-563.

Smith, A.C. (1979). Flora Vitiensis Nova. A new flora for Fiji (Spermatophytes only) 1: 1-495. Pacific Tropical Botanical Garden, Lawai.

Sykes, W.R. (2016). Flora of the Cook Islands: 1-973. National Tropical Botanical Garden, Hawaii.

Takeuchi, W. (2005). Floristic notes from a holocene successional environment in Papuasia. Harvard Papers in Botany 10: 95-116.

Thiombiano, A., Schmidt, M., Dressler, S., Ouédraogo, A., Hahn, K. & Zizka, G. (2012). Catalogue des plantes vasculaires du Burkina Faso. Boissiera 65: 1-391.

Whistler, W.A. (2022). Flora of Samoa Flowering Plants: 1-930. National Tropical Botanicl Garden. Smithsonian National Museum of Natural History.

Wilder, G. P. (1934). The flora of Makatea CNV. Bernice P. Bishop Museum Bulletin 120: 1-49.

Wilkin, P. & Thapyai, C. (2009). Flora of Thailand 10(1): 1-140. The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, Bangkok.

VERNACULAR NAME

Ambon: Kombili
Bikol: Baribaran
Cebuano: Apali
Chinese (simplified): 红薯
Chinese (traditional): 甘薯
Czech: Smldinec zelný
English: Lesser yam, Gembili, Asiatic yam
Filipino: Tongo, Aneg, Baribaran
Finnish: Pikkujamssi
French: Igname des blancs
Goa: Kaate Kanaga
Hanuabada: Diba
Ibanag: Aneg
Indonesian: Gembili, Ubi gembili
Java: Gembili
Khmer: ដំឡូងសៀ Dâmlông sya
Lao: ຮວາ ກະທັດ - ມັນອອນສ໌ Hwà kathad, Man 'onz
Malayalam: Nana kizhangu, Nheruvalli kizhangu, Cheru kizhangu
Malaysia: Ubi torak, Kembili, Kemarung
Motu: Taitu
Palauan: Chesiach
Pidgin: Mami
PNG: Mami, Taitu, Kalak, Diba
Polish: Pochrzyn słoniowy
Slovak: Dioskorea jedlá
Sunda; Aung
Tagalog: Tugi, Tongo
Thai: มันมือเสือ
Yatmei: Kalak

Aryo Bandoro
Dlium TheDlium
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