Origin of the term maize
The term maize seems to be derived from the word mahiz of Taino language of Caribbean islands, which became maiz in Spanish (Oxford dictionary, 2015). Based on this common name, Linnaeus included the name as species epithet in the botanical classification Zea (Z. mays L.). Maize is also known as corn in some English-speaking countries. Corn primarily means maize in USA (Oxford dictionary), Australia (Boberg, 2012) and New Zealand. In some countries corn means the local staple, while in some others it is used for any cereal. In US usage of the word corn seems to have started as a shortening of Indian corn, which primarily meant maize (the staple grain of indigenous people of America), but can refer more specifically to multicolored "flint corn" used for decoration. The terms mielie used in South Africa for maize or mealie (in English) are derived from the Portuguese term milho meaning maize (Oxford dictionary). However, in formal, scientific and international levels maize is the preferred usage as it is specific to this grain. The research institutes and agricultural organizations such as FAO, CSIRO and maize associations of many countries use the word Maize.
Geographic origin and diffusion
Most historians are of the view that maize was first domesticated in the Tehuacan Valley of Mexico (Roney, 2009) and the original wild form has been extinct since many years. It has now been established that the center of origin for maizeis the Mesoamerican region, now called Mexico and Central America (Watson & Dallwitz, 1992). Although maize pollen grains of 80000 years have been identified from Mexico City, clear cut archaeological records suggest that domestication of maize is at least 6000 years old. However, a study by Matsuoka et al. (2002) has demonstrated that all maize arose from a single domestication in southern Mexico about 9,000 years ago rather than the multiple independent domestications model. Then maize got diffused to other geographical regions. The geographic diffusion of maize throughout USA following the initial domestication in Southern Mexico (Piperno et al., 2009) remains contentious, with conflicting archaeological data supporting either coastal (Huckell, 2006) or highland (Ford, 1985) routes of diffusion of maize into the United States (Matsuoka et al., 2002). Fonseca et al. (2015) found by comparing nuclear DNA from 32 archaeological maize samples spanning 6,000 years of evolution to modern landraces that the initial diffusion of maize into the Southwest likely to have occurred along a highland route, about 4,000 years ago. This is followed by gene flow from lowland coastal maize beginning at least 2,000 years ago. Maize got diversified in the highlands of Mexico before spreading to the lowlands (Matsuoka et al., 2002). In 16th century, maize was introduced to Southeast Asia by the Portuguese from the America. The maize was brought into Spain by Columbus from America and from Spain it was introduced to France, Italy and Turkey. In India, maize was introduced during the seventeenth century by Portuguese. Later it went to China from India and was introduced in Philippines and the East Indies. Major corn growing countries now are USA, China, Brazil, Argentina, Mexico, South Africa, Rumania, Yugoslavia and India.