IV.

Varieties

The many varieties of corn show widely differing characteristics. Some varieties mature in 2 months; others take as long as 11 months. The foliage varies in intensity of color from light to dark green, and it may be modified by brown, red, or purple pigments. Mature ears vary in length from less than 7.5 cm (3 in) to as much as 50 cm (20 in). The number of rows of kernels ranges from 8 to 36 or more. Six general groups of varieties are differentiated by the characteristics of the kernel. Dent corn is the leading type of corn grown on U.S. farms. The sides of the kernel consist of hard, so-called horny starch, and the crown contains soft starch. As the grain matures, this soft starch shrinks, forming the characteristic dent.

In flint corn, the horny starch extends over the top of the kernel, so that there is no denting. Some varieties of flint corn, which are used for the same purposes as dent corn, are favored in cold climates because of their ability to germinate at low temperatures, or in tropical climates because of their resistance to attack by weevils. Popcorn is a light, highly popular snack throughout the United States, a variant of flint corn with small kernels of great hardness. When heated, the moisture in the kernels expands, causing the kernels to pop open.

Flour corn contains a preponderance of soft or less densely packed starch, and it is readily ground into meal. It is grown extensively in the Andean regions of South America that were part of the Inca Empire. Sweet corn is the type commonly grown in the United States for human consumption as a vegetable. The sugar produced by the sweet-corn plant is not converted to starch during growth, as it is in other types. The seeds are characteristically wrinkled when the plant is allowed to mature. Pod corn is seldom used as food but is often grown as a decorative plant; each kernel is enclosed in its own set of diminutive husks. Another decorative corn, commonly called Indian corn, consists of multicolored varieties of flour and flint types.