Jicama, also called Mexican yam bean or Mexican turnip, is naturally found in Mexico as well as in countries in Central and South America, but it was brought to Asia several centuries ago. The plant contains very little protein or fat and only the root can be eaten (raw).
From Wikipedia: “Pachyrhizus erosus, commonly known as jicama, Mexican yam bean, or Mexican turnip, is the name of a native Mexican vine, although the name most commonly refers to the plant's edible tuberous root. Jícama is a species in the genus Pachyrhizus in the bean family (Fabaceae). Plants in this genus are commonly referred to as yam bean, although the term "yam bean" can be another name for jícama. The other major species of yam beans are also indigenous within the Americas.
Flowers, either blue or white, and pods similar to lima beans, are produced on fully developed plants. Several species of jicama occur, but the one found in [many] markets is Pachyrhizus erosus. The two cultivated forms of P. erosus are jicama de agua and jicama de leche: both named for the consistency of their juice. The leche form has an elongated root and milky juice while the agua form has a top-shaped to oblate root, a more watery translucent juice, and is the preferred form for market.
Other names for jicama include Mexican potato, ahipa, saa got, and Chinese potato. In Ecuador and Peru, the name jicama is used for the unrelated yacón or Peruvian ground apple, a plant of the sunflower family whose tubers are also used as food.”
“Jícama is high in carbohydrates in the form of dietary fiber. It is composed of 86–90% water; it contains only trace amounts of protein and lipids. Its sweet flavor comes from the oligofructose inulin (also called fructo-oligosaccharide) which is a prebiotic. Jícama is very low in saturated fat, cholesterol and sodium. It is also a good source of potassium and vitamin C.”
“Jícama should be stored dry, between 12 and 16 °C (53 and 60 °F). As colder temperatures will damage the roots, jicama should not be refrigerated. A fresh root stored at an appropriate temperature will keep for a month or two.”
“The root's exterior is yellow and papery, while its inside is creamy white with a crisp texture that resembles raw potato or pear. The flavor is sweet and starchy, reminiscent of some apples or raw green beans, and it is usually eaten raw, sometimes with salt, lemon, or lime juice and chili powder. It is also cooked in soups and stir-fried dishes. Jícama is often paired with chili powder, cilantro, ginger, lemon, lime, orange, red onion, salsa, sesame oil, grilled fish, and soy sauce. It can be cut into thin wedges and dipped in salsa.
In Mexico, it is popular in salads, fresh fruit combinations, fruit bars, soups, and other cooked dishes. In contrast to the root, the remainder of the jícama plant is very poisonous; the seeds contain the toxin rotenone, which is used to poison insects and fish.”
“The leaves and pods are not edible. The toxic seeds are pulverized and used as insecticide. The stems have strong fibers and can be used to make fish nets.*”
Spread to China:
“Spaniards spread cultivation of jícama from Mexico to the Philippines (where it is known as singkamas, from Nahuatl xicamatl), from there it went to China and other parts of Southeast Asia, where notable uses of raw jícama include popiah, fresh lumpia in the Philippines and salads in Indonesia, Singapore and Malaysia such as yusheng and rojak.”
Note (italics): * = Translation from a German Wikipedia entry