Yam Bean, Jicama, Mexican Yam
Pachyrhizus erosus

Family: Fabaceae

What it is like

Yam Bean or Pachyrhizus erosus, otherwise known as Jicama, Mexican yam bean, or Mexican turnip, is a perennial vine producing annual stems 2 - 6 m long from a tuberous rootstock. The root can weigh up to 20 kg. The leaves are alternate and comprised of three leaflets. There is no known medicinal uses of yam bean but it is often cultivated for food. The root is eaten raw or cooked. It is crisp, sweet, and juicy. Starch extracted from the roots is used in custards and puddings. The seeds and leaves, however, contain a poisonous glucoside. The plant has a symbiotic relationship with certain soil bacteria that form root nodules and fix atmospheric nitrogen. Due to this, it is also used as green manure. Yam bean can also be used as an insecticide for it contains rotenone.

Pachyrhizus erosus is a CLIMBER PERENNIAL growing to 6 m (19ft) by 1.5 m (5ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 10. It can fix Nitrogen. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: neutral and basic (mildly alkaline) soils and can grow in very alkaline soils. It cannot grow in the shade. It prefers moist soil.

Height (m): 6

Where it is found

Not known

Central America - Mexico.

Conservation Status: This taxon has not yet been assessed

Countries/locations it is found in

Africa, Antigua-Barbuda, Antilles, Argentina, Asia, Australia, Bangladesh, Belize, Bhutan, Brazil, Burma, Cambodia, Cameroon, Central Africa, Central America, China, Congo, Cook Islands, Costa Rica, Cuba, Dominica, Dominican Republic, East Africa, East Timor, El Salvador, Fiji, French Guiana, Ghana, Guadeloupe, Guam, Guatemala, Guinea, Guinée, Haiti, Hawaii, Honduras, India, Indochina, Indonesia, Jamaica, Japan, Laos, Madagascar, Malaysia, Maldives, Martinique, Mauritius, Mexico*, Myanmar, New Caledonia, Nicaragua, North America, Northeastern India, Pacific, Palau, Panama, Papua New Guinea, Paraguay, Peru, Philippines, Puerto Rico, Reunion, SE Asia, Senegal, Sierra Leone, Singapore, Solomon Islands, South America, Sri Lanka, St Lucia, Tahiti, Taiwan, Tanzania, Thailand, Timor-Leste, Trinidad & Tobago, USA, Vanuatu, Venezuela, Vietnam, West Africa, West Indies,

How it is used

Food

Rating: 4

Edible root - raw or cooked. Crisp, sweet and juicy, it tastes somewhat like an apple when raw and a water chestnut when cooked. The root stays crisp and does not discolour after being cut. It also stays crisp after being cooked, which makes it a popular substitute for water chestnuts in Chinese cooking. A starch extracted from the root is used in custards and puddings. The root is harvested before it matures and becomes fibrous, when the plant has been growing for about 6 months and the tuber weighs about 2 kilos. Mature tubers can reach 2 metres long and weigh up to 20 kilos. Young seedpods - cooked and used as a vegetable. They must be thoroughly cooked in order to destroy the poisonous principle rotenone.

Root: includes bulbs, corms, tubers, rhizomes etc.

Seedpod: things such as Okra, French and Runner beans.

Medicine

Rating: 0

Other

Rating: 2

Agroforestry Uses: The plant can be used as a green manure. Other Uses The plant contains rotenone, the active ingredient in the insecticide 'derris', and it has the potential to be used as an insecticide. Derris is a relatively safe insecticide in that it does not affect warm-blooded animals and also breaks down into harmless substances with 24 hours of being used. It does, however, kill some beneficial insects and is also toxic to fish and amphibians.

Green manure: Fast-growing plants that can be used to increase the fertility of the soil.

Insecticide: Kills insects.

Food Forest: Plants for Edible Forest Gardens and Food Forests.

Nitrogen Fixer: Plants that fix nitrogen in the soil

How it is grown

Plants are tolerant of a wide range of climatic conditions but grows best in lowland tropical areas at elevations up to 1,000 metres and a moderate rainfall. The plant grows best in areas where the mean minimum temperature is about 20°c and the maximum is 30°c, though they can succeed where they are 15 - 36°c. It prefers an annual rainfall in the range 1,300 - 1,700mm, but can tolerate 250 - 7,000mm. Grows best in a sunny position. Tolerates a wide range of soils. Prefers a light, rich, well-drained, sandy soil. Dislikes water-logged soils. The plant prefers a pH in the range 6.5 - 8, but can tolerate 4.3 - 8. Immature pods are ready for harvest about 200 - 240 days from sowing. Tubers may be harvested after 150 - 270 days, before they become fibrous. In warmer parts of Mexico with light, rich soil, mature tubers are commonly harvested after only 90 days. Seed crops takes about 300 days to mature. A short-day plant, it requires between 11 - 13 hours of daylight hours per day in order to initiate tuber production, though vegetative growth is normal even in relatively long days of 14 - 15 hours. When grown for its edible root the flowers and seedpods should be removed. There are some named forms. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby. Flowering Time: Mid Fall. Bloom Color: Blue-Violet. Spacing: 6-9 in. (15-22 cm).

Propagating it: Pre-soak the seed for 12 hours in warm water and then sow in situ. Division of the root tubers. Cuttings.

Best place to grow:

Habit: Climber Perennial

Hardiness: 9-12

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Moist

Things to keep in mind

Seeds and leaves are poisonous. The leaves, mature seedpods and the seeds contain a poisonous glucoside. (Seed is poisonous if ingested Parts of plant are poisonous if ingested )

Its other names

Local names

Yam Bean, Jicama, Mexican Yam, Mexican Potato, Yambean, Mexican Turnip, Ahipa, Ajipo, Auyey, Bangkwang, Bengkowang, Bunga, Carota de caballo, Chopsui potato, Cu dau, Cu san, Dou-su, Erosus yam bean, Fan-Ko, Frijol de jicama, Frijol name, Huwi hiris, Jicama de agua, Jicama de leche, Kuzu-imo, Man kaew, Man keo, Mexican potato, Nupe, Pachyrrhize, Patate-cochon, Pek kuek, Pois cachou, Poroto batata, Saa got, Sankalu, Sankeh alu, Sankulu, Sbai kalendre, Sengkuang, Sha ge, Sha kot, Shak-alu, Singkamas, Singkong, Singkwang, Sinkamas, Thua phuu, Ubi sengkuang, Ubi sengkung, Uisulbe, Yaka, Yuco de bejuco, mexican turnip, potato-bean, yam bean, yam-bean.

Synonyms

Cacara bulbosa Rumphius ex Du Petit-Thouars Cacara erosa (L.) Kuntze Cacara palmatiloba (Moc. & Sess