Maize, corn
Family Gramineae (or Poaceae)
Zea mays, maize, corn or Indian corn (Z. mays 1), is the most important cereal after wheat and rice. It is a stout annual grass, 1-4 m high, with a single stem and clearly defined nodes and internodes. The lowest internode bears adventitious roots (Z. mays 2) for extra support. Leaves with linear blades, acuminate, up to 150 cm long, and a pronounced midrib. Maize is a monoecious plant, with male and female flowers borne in separate inflorescences. The male inflorescence or ‘tassel’ is a terminal panicle, up to 40 cm long, with a variable number of lateral branches bearing paired spikelets. Each spikelet has 2 glumes containing 2 flowers with 3 stamens each. The female inflorescences or ‘ears’ (Z. mays 3) are modified spikes and are carried lower down the stem. The ear is covered by modified leaves, which form the ‘husk’. Between these leaves at the tip of the ear protrudes the ‘silk’ , composed of the long thin styles of the female flowers which will receive the pollen from the male flowers (Z. mays 4). The ear consists of a central structure, the ‘cob’ , on which the grains are set in rows (Z. mays 5), (Z. mays 6). Usually 1-3 maize ears mature on each plant.
Distribution
Maize is the only cereal of American origin. It is likely that it reached Peru from Mexico as early as 1000 BC. It was the staple food for the Indians. At the time of the discovery of the New World by Columbus, maize had spread widely. It also played an important role in the conquest of the Americas when the Spaniards and later the English settlers took over the maize cultivation from the Indians. Later, in the 18th century, it played a major part in the development of the Midwest and became established in what is now known as the Corn Belt. Today there are about 33 million hectares under maize cultivation there.
In 1496 Columbus took seeds with him back to Europe resulting in a quick spread around the Mediterranean. Next, the Spaniards and Portuguese spread it through the tropics and it reached China in about 1573. Most likely the Portuguese also took maize to West Africa, where it was a major cash crop during the period of slave trade. They probably also introduced it in East Africa, where it is reported on Zanzibar in 1643.
Today, maize is grown from 50 degrees North to 40 degrees South and from sea level to over 3000 m in the Andes. The many varieties are divided into groups according to the structure of the grain, e.g. dent, flint, pop, sweet, etc.
Use
Maize is used for three main purposes: as a staple human food in the tropics (Z. mays 7); as feed for livestock in the temperate regions (Z. mays 8); and as a raw material for industrial products.
For human consumption maize is prepared and consumed in a multitude of ways. The grain is usually ground into a meal that may be boiled, baked or fried. Also the whole grain may be boiled or roasted. Cooked with water the meal provides porridge, which is the commonest method of eating it in Africa. In Latin America tortillas are made by baking flat cakes until they are crisp. In North America cornbread is made by mixing meal with wheat flour. Meal itself is unsuitable for making bread, as it is deficient in gluten. Immature cobs are eaten as a vegetable. They are also canned. Rolling pre-cooked grains after they have been flavoured makes cornflakes. Popcorn is made by heating small grains, which explode or pop, turning themselves inside out. Waxy maize is used for the production of starch, which can be used as a thickener, laundry starch and for the production of industrial products. Sweet corn is eaten ‘on the cob’ after boiling. In this type of maize the conversion of sugar into starch is retarded. Maize oil, extracted from the embryos, is increasingly important as a cooking-oil.
Industrial products made of maize include several types of alcohol and acids. The stems can be used for papermaking; the leaves may be plated into mats. Altogether, several hundreds of products and by-products of maize are recorded.