Geographical distribution and history: Corn is undoubtedly of American origin. It was grown by the Indians long before the discovery of America. The Incas of Peru are said to have built large storerooms for it, to prevent famine in case of crop failure. It was grown as far north as the St. Lawrence valley when the first explorers arrived there. Ears of corn are often found in old Indian tombs, deposited with the deceased as provision for the long journey to the happy hunting grounds.
Where or when it was first cultivated, or from what wild plant it developed, is not definitely known. It is generally assumed that its cultivation started in Central America and spread north and south. It has never been found wild. This might either mean that wild corn was extinct before botanists could make a record of it, or that it is a plant so different from the cultivated form that it is now impossible to recognize it. The latter assumption is the one generally favoured, and the plant mentioned as the probable primitive form is the Mexican Teosinte (Euchlaena mexicana Schrad.). Although very different from corn in its general appearance, Teosinte is evidently closely related to it, as is shown by the fact that hybrids obtained by crossing the two produce germinable seeds. Though this is not conclusive proof, it is evidence that corn may have developed from Teosinte, for in all other known cases hybrids between distinct grass species are sterile.
Climate: Being of southern origin, corn requires a warm, moist climate. In the north, where the season is short and the weather comparatively cool, only the earliest varieties reach full maturity under ordinary conditions.
Soil: It demands a warm, fertile soil and thrives best in a deep, rich loam, well drained yet stored with abundant moisture. A good supply of organic matter, furnishing readily available plant food, will increase the yield considerably. Poor sandy soils, or soils with the water table near the surface, do not allow the roots to gather sufficient nourishment. In stiff clay, or in soils which form a hard-pan subsurface, the growth is slow and the yield uncertain, especially in dry weather.
Varieties: Corn includes hundreds of agricultural varieties. This is chiefly due to the readiness with which cross-fertilization takes place between individuals of different types. Some varieties are dwarfs, no more than eighteen inches high; others are giants,