Oca

In the Andean highlands, only the potato is a more important root crop than oca (Oxalis tuberosa). But whereas the potato has spread to become the world's fourth largest crop, oca (pronounced oh-kah) is little known outside its ancestral home. This is unfortunate because oca tubers have great consumer appeal: brilliant colors and a pleasant flavor that many people find a welcome change from the potato.

Oca tubers look like stubby, wrihkled carrots. They have firm, white flesh and shiny skins in colors from white to red. Most varieties have a slightly acid taste—they have been called “potatoes that don't need sour cream.” Others, however, give no perception of acidity. Indeed, some are so sweet that they are sometimes sold as fruits.

An attractive, bushy plant with cloverlike leaves, oca is easy to propagate, grows luxuriantly, requires little care, and is exceptionally tolerant of harsh climates—under which its yield can be twice that of the potato. Moreover, it prospers in poor soils and at altitudes too high for most food plants. From Venezuela to Argentina, oca is still a staple for Indians living at altitudes between about 3,000 and 4,000 m. For them, oca tubers are principally sources of carbohydrate, calcium, and iron.

Although scarcely known outside the Andes, oca has found a home in Mexico, where it has probably been grown for more than 200 years. ¹ And in the last 20 years it has become popular in New Zealand, where the tubers—sold under the misleading name “New Zealand yam”—are now commercially cultivated. This provides an important glimpse of oca's potential future because the climate, latitude, altitude, and daylength regimes of New Zealand are similar to those of some farming regions of North America, Asia, and Europe. Thus, like the potato before it, oca could become a vegetable for temperate zones.

Wherever it is cultivated, this crop is likely to be readily accepted. It lends itself to many culinary traditions because it can be prepared