The jicama has been called a “Mexican potato” since at least 1972; jicamas became popular in the United States since the early 1970s. The bulbous root vegetable is a member of the legume family and can be eaten raw or cooked.
 
The jicama has also been nicknamed “Mexican turnip” since at least 1976.
   
 
Wikipedia: Jicama
Jícama (Spanish: hee-kah-mah, from Nahuatl xicamatl hee-kah-mahtl), also Mexican Potato and Mexican Turnip, is the name of a native Mexican vine, although the name most commonly refers to the plant’s edible tuberous root. Jicama is one species in the genus Pachyrhizus that is commonly called yam bean, although the “yam bean” sometimes is another name for Jicama. The other, major species of yam beans are also indigenous within the Americas. It very much tastes like a sweet pea pod.
 
The jicama vine can reach a height of 4-5 metres given suitable support. Its root can attain lengths of up to 2 m and weigh up to 20 kilograms. 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. It can also be cut into thin wedges and dipped in salsa as a healthier alternative to corn chips.
 
Due to its growing popularity, cultivation of jícama has recently spread from Mexico to other parts of Central America, China and Southeast Asia where notable uses of raw jícama include popiah and salads such as yusheng and rojak. Jícama has become popular in Vietnamese food, where it is called cây củ đậu (in northern Vietnam) or củ sắn or sắn nước (in southern Vietnam). It is known as by it’s chinese name bang kuan to the ethinc chinese in the south east asia region.
 
In Mexico it is very popular in salads, fresh fruit combos, 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.
 
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 flavour comes from the oligofructose inulin (also called fructo-oligosaccharide).
 
Jícama should be stored dry, between 12°C and 16°C (53°F and 60°F); colder temperatures will damage the root. A fresh root stored at an appropriate temperature will keep for a month or two.
           
Epicurious.com - Food Dictionary
jícama
[HEE-kah-mah]
Often referred to as the Mexican potato, this large, bulbous root vegetable has a thin brown skin and white crunchy flesh. Its sweet, nutty flavor is good both raw and cooked. Jícama is available from November through May and can be purchased in Mexican markets and most large supermarkets. It should be stored in the refrigerator in a plastic bag and will last for about 2 weeks. The thin skin should be peeled just before using. When cooked, jícama retains its crisp, water chestnut-type texture. It’s a fair source of vitamin C and potassium. 
 
Merriam-Webster Dictionary
Main Entry: ji·ca·ma
Pronunciation: \ˈhē-kə-mə\
Function: noun
Etymology: Mexican Spanish jícama, from Nahuatl xīcamatl
Date: circa 1909
: an edible starchy tuberous root of a tropical American vine (Pachyrhizus erosus) of the legume family that is eaten raw or cooked
   
The Cook’s Thesaurus
jicama = jícama = yam bean = Mexican yam bean = ahipa = saa got = Chinese potato (this name also is used for arrow root) = Mexican potato = Chinese turnip (this name also is used for lo bok)
Pronunciation:  HIH-kuh-ma
Equivalents:  One jicama, cubed = 2 cups
Notes:  This tan-skinned tuber has a mild, nondescript flavor, but a nice crunchy texture. It’s a good, cheap substitute for water chestnuts in stir-fries.  Since it doesn’t discolor, it’s also a great vegetable to serve raw on a crudité platter. Peel it before using. 
Substitutes: water chestnuts (These are more expensive and sweeter than jicama. Like jicama, water chestnuts retain their crispiness when stir-fried.) OR Jerusalem artichoke ( Like jicama, these can be eaten raw and they stay crunchy even when stir-fried. They’re more expensive than jicama, but they have an earthier, nuttier flavor.) OR tart apples OR turnips OR daikon radish  
 
1 June 1972, Tucson (AZ) Daily Citizen, “Some vegetables ‘exotic,’ not ‘weird’” by Barbara Barte, pg. 14, col. 2:
Jicamas are grown in Mexico and sometimes referred to as “Mexican potatoes.” They look like big, brown turnips and, according to their fanciers, are a good substitute for apples.
 
22 March 1973, Montclair (CA) Tribune, pg. 5 ad:
JICAMA
(MEXICAN POTATOES)...19c lb
(Bill’s Ranch Market—ed.)
   
5 December 1973, Oxnard (CA) Press-Courier, “Use Fruits, Vegetables In Season” by Marilyn Godrey, pg. 23, col. 1:
Jicama (pronounced HEE-cah-mah) is a root vegetable you may not be familiar with. It is sometimes called the Mexican potato. It is grown in tropical climates and available in most stores. When choosing jicama, select ones that are very firm. They are usually served raw in salads or sprinkled with lime juice and salt.
 
6 March 1974, Yuma (AZ) Daily Sun, pg. 17, col. 1 ad:
Fresh Jicama
Mexican Potato
Eat Raw or Cooked
lb. 25c
(Safeway supermarket—ed.)
 
Google News Archive
7 August 1975, St. Petersburg (FL) Times, “Playing the (super) market” by Ruth Gray, pg. D1, col. 4
JICAMA (sometimes spelled Jaimaca)(“Jaicama” was probably the intended spelling—ed.) is a starchless Mexican potato-like vegetable, is a great thirst quencher and has a bland flavor. Use it as a substitute for water chestnut (which usually costs more). Cut in thin slices, spinkle with sugar, or soak for 30 minutes in salted water and bake as a potato (though flavor differs from the potato when it is baked). Smaller jicama are less woody than larger ones.
 
15 October 1975, Daily Inter Lake (Kalispell, MT), pg. 7, col. 1 ad:
“Peel and slice—eat raw or steam”
(Mexican Potato)
JICAMA…39c
(B&B Stores—ed.)
     
New York (NY) Times
Food; ASPARAGUS: ABUNDANT, DEWY FRESH AND LOW-PRICED
By FLORENCE FABRICANT
Published: May 29, 1983
(...)
Note: Jicama (pronounced HICK-a-muh), sometimes called a Mexican potato, is a large round tuber with a rough brown skin. You will find it in markets that sell Hispanic vegetables. About one-third of an average jicama slivered will yield a cup.
 
Google Books
25 May 1987, New York magazine, pg. 12A, col. 2:
It would be easy to overlook the jicama in the produce market. Also called Mexican potato, the jicama has brown, easily peeled thin skin and is shaped like an oversized turnip, says Carol Bowman-Williams, consumer and information specialist at Frieda’s Finest/Product Specialties, the Los Angeles-based importer of exotic produce that popularized the kiwi in the United States.
 
“The jicama should be peeled and may be eaten either raw of cooked,” says Bowman-Williams. “Its white flesh has the crispness of apples and a mild flavor.” Jicamas are imported from Mexico, where they are often served dipped in chili powder or lime juice. Because the vegetable is 90 percent water, it is low in calories—about 100 per cup.
   
Google Books
Latin American Cooking Across the U.S.A.
By Himilce Novas and Rosemary Silva
New York, NY:
1997
Pg. 196:
Jicama
Nicknamed “yam bean” and “Mexican potato,” this low-cal tuber comes in many sizes and is usually shaped like a turnip.
 
Google Books
Pocket Culinary Art Dictionary:
Portuguese-English, English-Portuguese
By Aline Endres
New Global Publishing
2008
Pg. 40:
jicama—jicama, mexican potato, mexican turnip.