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The plant known internationally as yambean is arguably one of the most interesting of all the world’s new food crops.12 This species, which hails from the Americas, looks like a bean plant above ground but is actually grown for the swollen roots it produces below ground. Since the dawn of history these yam-like tubers have fed tropical Americans. Then Spanish galleons3 carried the seed across the Pacific, and this productive, palatable, and nutritious legume subsequently spread through Asia and became a market-garden favorite from China all the way to India.

In recent decades yambean has taken on renewed momentum and is now among the world’s fastest rising new crops. Already it is the top selling specialty vegetable in the United States, its tubers being sold in many (if not most) U.S. supermarkets under its Mexican name, jicama. Americans buy the round, squat tubers for use in salads, for replacing scarce water chestnut in Chinese cooking, and for a low-calorie snack food. Demand has risen to such an extent that Mexico now exports half a million tons annually.4

In Europe, this food is catching on, too. Part of Thailand’s large yambean output, for instance, is now shipped to many Asian stores in major European cities. This American crop has even entered production trials in Portugal, where, under conditions seemingly so different from its native tropical habitat, it has demonstrated very impressive yields: 54 tons per hectare, with up to 24 percent dry matter containing 10 percent crude protein.5


Several Pachyrhizus species go by this name, but the best known and best developed yambean is Pachyrhizus erosus. It mostly goes by local or indigenous names, including fan-ko (China), sankalu (India), sinkamas (Philippines), dolique tubereux or pais patate (French), Knollige Bohne (German).


Information in this chapter relies heavily on Sørensen, M. 1996 Yam bean (Pachyrhizus DC.). International Plant Genetic Resources Institute, Rome, and personal communications with this tireless Danish crop champion.


Amazingly, these galleons crossed the Pacific from Mexico to the Philippines annually without fail for 400 years.


Its wholesale price has reached $2.50 a kilo, an amazing figure for a root crop traded in bulk.


The yambean here was the Andean species (Pachyrhizus ahipa), and the range of

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