THE POTATO OF THE HUMID TROPICS

Taro, dasheen, or cocoyam (Colocasia esculenta var. antiquorum)

ARACEAE, Arum Family

About 10% of the world's population uses taro or taro-like plants (Araceae) as a staple in the diet, and for 100 million people this is an important daily food. The Colocasia taro is a very common crop for wet soils in the humid tropics, especially in Southeast Asia, the Pacific Basin, wet tropical Africa and Egypt, the West Indies, and certain areas of South America; the yautias (Xanthosoma), close cousins of taro, are native to and grow mostly in the New World. The chief food from these plants is the "corm," an erect, starchy, underground stem, which grows to be over a foot long, but leaves are also consumed.

Taro has leaves that are 1 to 2 meters long with a long, erect petiole and an arrow-shaped blade. Plants like this are sometimes called "elephant ear." The plants rarely flowers and never set seed, so vegetative propagation via replanting portions of the corm is the only way to grow this plant. In fact, general absence of flowering is one piece of evidence that formerly was used to show the ancient origin of taro, because plants that have lost their ability to reproduce in the wild are usually judged to have been in cultivation a long time. Taro is propagated vegetatively by removing the upper half inch of the corm with the shoot (Hawaiian huli), or via smaller axillary corms. Hulis grow well where the soil is constantly wetted until new leaves are well developed. Particular forms of taro can also be grown in drier soil with the use of good mulches to preserve soil moisture.

Authors surmise that both types of taro were ancient root crops, without having much direct evidence, and some workers even have speculated that taro and yautia were among the first of all cultivated plants, because natives learned to eat the bottom portion of the corm and then replant the leaves and top of the corm, so that they could return in ten months for a new crop. It was probably first native to the lowland wetlands of Malaysia (taloes). Estimates are that taro was in cultivation in wet tropical India before 5000 B.C., presumably coming from Malaysia, and from India further transported westward to ancient Egypt, where it was described by Greek and Roman historians as an important crop. The ancient Egyptian word for taro was colcus or kulkas; the ancient Arabic word was qolquas; and the Greek word was colocasia, which is now the generic name. Taro also spread eastward into ancient China and Indonesia. The common name "dasheen" presumably came from de Chine (Fr., from China), although this is probably not the place of origin for this crop but instead the earliest documentation of its use. The Maoris took taro to New Zealand, presumably aboard massive sea crafts like a Fijian camakau. Students of Pacific islanders have traced the migration of taro with the Polynesians from Indonesia and New Zealand eastward to the Hawaiian Islands (called kalo), where it presumably arrived in 450 AD Taro also became successful in tropical Africa and reached the New World tropics when carried to the Western Hemisphere for slave food in the West Indies.

When Captain Cook discovered the Hawaiian Islands in 1778, the native population (est. 300,000) lived chiefly on dasheen and sweet potatoes (Ipomoea batatas), supplemented with things from the sea. In the Hawaiian Islands, taro was said to have been formed by the union of daughter earth and father sky, before man was born, so taro was honored as superior to man and treasured as the most important food crop. So intensive was its cultivation there that there may have been up to 300 cultivars in Hawaii when Captain Cook landed. Poi was traditionally prepared by removing the corm "skin" and then pounding the white flesh on a board with a stone pounder (pohaku ku'I) to make a thick paste, which was dried, diluted with water, kneaded, and then aged. The infamous Polynesian poi may be fermented (first bacteria, then yeast) or sometimes unfermented forms of this sticky dasheen paste, eaten with the fingers or as small balls. Some Polynesians were said to consume up to 20 pounds of poi per day!

Taro corms are roasted, boiled, or baked, and may be made into cakes. Heating is necessary to remove an acrid, irritating property of the raw corm. Traditionally, the substance blamed for this irritation has been the needle-like crystals of calcium oxalate, which occur throughout the plant and become lodged in the mucous membranes of the mouth and throat. Dumbcane (Dieffenbachia), a household plant, is considered a dangerous poison for the same reason. Now other researchers suspect that one or more additional chemicals may be responsible for the acridity and intense itching and burning of raw taro, which would be injected into mucous membranes by the sharp-tipped calcium oxalate crystals. In the Hawaiian Islands, taro plant is eaten after thoroughly boiled to destroy the toxins; the leaf (luau, also the name of the feast using taro leaves) must be boiled at least 45 minutes over low heat, whereas corms are boiled in a deep pot with salted water for at least an hour or until soft.

Taro is similar to the Irish potato (Solanum tuberosum) in many properties, and is sometimes called the "potato" of the humid tropics. In comparison with potato, taro corm has a higher proportion of protein (1.5-3.0%), calcium, and phosphorus; it has a trace of fat, and is rich in vitamins A and C. Moreover, taro is 98.8% digestible, because it has very small starch grains fairly rich in amylose (20-25%), which breaks down to sugar with human saliva. This type of carbohydrate is excellent for people with digestive problems, so that taro flour is used in infant formulae and canned baby foods and is good for people with allergies, such as lactose intolerance. Some workers say that taro produces fewer dental problems than other starch crops. Recent research indicates that plastics can be made to be biodegradable by adding taro starch grains.

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