The original process of plant selection seems to have been carried on more intensively in the Americas than elsewhere. The major crop plants were farther removed from their wild ancestors than those of any other part of the earth at the time of the discovery. Mention need only be made of corn, which is so distinct as to require classification in a unique genus, and of the potato, which resulted probably from the crossing of many and various Solanaceae.
[The Solanaceae include nightshade, jimson weed, tobacco, and others.] It is ironic that, as O. F. Cook has observed, the white potatoes grown each year are worth more than all the gold that the Spaniards took from the Incas.[14] This is probably still truer of Indian corn.
[Illustration: THE FIRST ILLUSTRATION OF THE CORN PLANT
_From Fuch’s_ De Historia Stirpium, _published in 1542, only fifty years after Columbus’s men first saw maize. Seven years earlier, Oviedo printed a drawing of an ear of corn. (Courtesy of Harvard University Library.)_]
On November 5, 1492, two Spaniards whom Columbus had sent into the interior of Cuba told him of “a sort of grain they call maiz which was well tasted, bak’d, dry’d, and made into flour.” Thus came the first news of what P. C. Mangelsdorf and R. G. Reeves, authorities on corn, call “a cereal treasure of immensely greater value than the spices which Columbus traveled so far to seek.”[15]
The fact that corn is today the second most important food crop of the world is due to its unique adaptability. In 1492 at least seven hundred different varieties of this grain were growing in widely varied areas of half the western hemisphere. Today corn is grown on all the continents, and its habitats range from 58° north latitude in Canada and Russia to 40° south of the equator in Argentina.
Fields of maize are growing below sea level in the Caspian plain and at altitudes of more than 12,000 feet in the Peruvian Andes. Corn is cultivated in regions of less than ten inches of annual rainfall in the semi-arid plains of Russia, and in regions with more than 200 inches of rain in the tropics of Hindustan. It thrives almost equally well in the short summers of Canada and the perpetual summer of tropical Colombia.[16]