(Pachyrhizus erosus and P. tuberosus— Family Leguminoseae)
Jicama, yam bean, potato bean, manioc bean, turnip bean, chop suey yam/chopsui potato (Hawaiian), singkamas (Philippines), dou shu and sha got (Chinese)
Jicama (pronounced HEE-kah-mah) are the fruits of climbing tropical legumes.
The main difference between the two varieties is that the pods of P. tuberosus are rarely eaten because of irritating hairs. The other forms large, edible tubers, and is native to Central and South America.
The young pods of this plant may also be eaten, but the mature pods and seeds are toxic.
Interestingly, because of the nitrogen fixation of legumes, the tubers of leguminous plants are generally more nutritious than such other tubers as potatoes.
Various yam species are native to a wide area extending from Northern South America to Mexico.
In Ecuador, the name jicama is used; but, in Peru, it is called yacon, which is also the name of a totally unrelated plant (Polymnia sonchifolia)
of the Sunflower family (Compositae) indigenous to the Andean region of South America.
The Spanish took the tuber to the Philippines during the 16th century. Since then, they have found their way around the world, including Hawaii where it is known as the “chop sui potato”.
Today, most of the production takes place in humid tropical areas of the Western Pacific and in Southeast Asia.
Unlike other tropical tubers, jicama is grown from seed, and takes about ten months for their tubers to mature. The tubers are a fair source of protein, but low in vitamins.
At its prime, when peeled and eaten raw, jicama has a flavour reminiscent of a cross between and apple and a water chestnut.
This crunchy vegetable looks like a misshapen beetroot, only it is the colour of a medium brown potato.
It can be eaten raw or cooked, but it is more enjoyable raw as the crunchiness does not diminish with cooking. Therefore, it can be substituted for water chestnuts in any recipe.
Jicama must be peeled, sliced, and covered in water and stored in the refrigerator; but the water should be changed daily.
Avoid carbon knives and cast iron pots as both will discolour the vegetable. In addition, the larger the tuber, the more starch it will have.
It is the smaller ones which are the sweetest and juiciest. Jicama is a good source of vitamin C, potassium, and folate.
The African yam bean (Sphenostylis stenocarpa)
has many local names. Its starchy tubers look like sweet potatoes, but taste more like ordinary potatoes. The seeds are also edible if they are soaked before being cooked. It is an important source of protein and starch for the Africans.
As explained under the winged bean, the tubers of leguminous plants are much more nutritious than other root crops because of their nitrogen fixation.