 I. Corn is one of the most valuable cereal grain (a seed of the cereal grain plant) crops grown in the United States and the world. There are six common types of this versatile crop.

 A. Corn types are classified based on kernel characteristics: amount, quality, and arrangement. The six most common types of corn are dent corn, flint corn, floury corn, popcorn, sweet corn, and pod corn.

 1. Dent corn, Zea mays indentata, is the most common type of corn grown in the United States. It is referred to as field corn. The crowns of the kernel are dented, giving the corn its name. This denting occurs when the starch at the end of the crown shrinks during drying. Dent corn can be yellow, white, or red. The length of the growing period varies by cultivar.

 2. Flint corn, Zea mays indurata, is a popular source of corn meal. Most cultivars mature fairly quickly, even under poor conditions. Flint corn is resistant to many insects and can be shipped overseas because of its kernel hardness, which is due to the makeup of the kernel. The center is composed of only a small amount of soft starch surrounded by a thick layer of hard starch. Flint corn comes in many colors, including white, yellow, red, and blue.

 3. Floury corn, Zea mays amylacea, is also called soft corn. The kernels of soft corn are composed primarily of soft starch with a thin covering of hard starch. The lack of a thick, hard starch layer makes this corn type a good choice for flour production. Floury corn comes in several colors, including white and blue.

 4. Popcorn, Zea mays everta, cultivars are divided into two classes: pearl and rice. This division is based on the shape of the kernel. Popcorn kernels are smaller than flint corn kernels and are composed of a hard, flinty starch. Some cultivars have a soft starchy center. The kernels are usually white or yellow, but they may be red, blue, or brown. When popcorn is “popped,” the moisture inside the kernel is heated until it becomes steam. This causes pressure that causes the kernel to explode. The white or yellow flaky material is the starch from inside of the kernel.

 5. Sweet corn, Zea mays saccharata, is most commonly grown for human consumption. Sweet corn is picked while still immature to retain the high sugar content. Sweet corn kernels are white or yellow and may be wrinkled or become caramelized in color when fully mature.

 6. Pod corn, Zea mays tunicata, has little commercial importance and is commonly grown as a specialty item. Pod corn kernels are enclosed in a husk or pod, and the ear is surrounded by a large husk.

 1. The kernel is the part of the individual grain within the seed coat. Corn kernels are enclosed in a seed coat, which is the outer covering of a seed. Inside the seed are the embryo (undeveloped seedling) and the endosperm.  2. Corn kernels contain two types of endosperm: starchy and flinty. The endosperm is the food for the seedling inside the seed. Starchy endosperm is soft, and flinty endosperm is hard. The amount of each type determines how the corn can be used.  3. The ends of the corn kernel are the crown and the hilum. The crown is the outer end of the corn kernel, and the hilum is the point of attachment on the seed.

 B. Corn, or Zea mays, is used for human and animal consumption. In addition, corn byproducts can be used to make numerous nonfood products.  1. As a livestock feed, corn is used for fattening. It is also the most palatable, or pleasant tasting, of the cereal crops. Corn can be used in high concentrations in dairy cattle feed and is also used in poultry mash. The kernel is high in starch, which is a carbohydrate and a good source of energy.

 2. Humans are also consumers of corn and corn products. Common human food products include corn meal, corn hominy, corn flakes, corn chips, corn starch, corn oil, corn syrup, corn sugar, and popcorn.  3. A number of byproducts can be made from the corn plant. The stalks can be processed into paper, insulation, and cardboard. The cobs can be processed into pipes, methanol, tar, and plastic. The cob grit can be used to clean and polish buttons and jewelry. Also, corn cob dust can be made into face powder.

 II. Corn plants are members of the grass or Gramineae family. They are classified as annuals and monocots.

 A. Corn plants are supported by a stem or stalk. Most commercial field corn varieties grow to about eight feet in height, but sweet corn varieties are usually a bit shorter.  B. Alternating along the stem (at intervals of approximately 8 to 12 inches) are long narrow leaves with parallel venation. Depending on the variety, the leaves measure from 2- to 4-feet long and 2- to 4- inches wide.

 C. Corn plants have fibrous root systems and are supported by smaller roots called prop roots, which are above- ground roots that aid in keeping plants erect.  D. Corn is monoecious, so it has male and female flowers on the same plant. The reproductive structures of a corn plant are the “ear” and “tassel.”

 1. The female reproductive part of the corn plant is the ear. The ear is attached at the base of a leaf at a node of the stem. As the plant reaches sexual maturity, silk or elongated styles grow from the ear. The silk looks like a tuft of hair and is green before turning yellow or red. Each style is connected to an ovary, and every style must be pollinated to achieve a full ear of kernels or grains of corn.

 2. The tassel is the male reproductive part of the corn plant. It is held at the apex of the stem. Pollen produced by the tassels is carried by the wind and rain to the silk.  3. Corn ears are enclosed in husks. The husk is the leafy, protective covering that surrounds ears of corn. The corn kernels grow on ears that vary in size, shape, and color, dependent on variety.

 III. Corn was domesticated in Mexico around 9000 B.C. It is the most important grain crop in the United States and is one of the leading grain crops worldwide. Corn is commonly grown throughout the Midwest. However, with sweet corn and other varieties becoming more common in gardens, corn is grown in just about every state. Yet corn remains a large import for some countries and a large export for the United States.

 A. According to the USDA National Agriculture Statistics Service, the top five corn-producing states are (1) Iowa, (2) Illinois, (3) Nebraska, (4) Minnesota, and (5) Indiana. The 10 major corn-producing states are (1) Illinois, (2) Indiana, (3) Iowa, (4) Kansas, (5) Minnesota, (6) Missouri, (7) Nebraska, (8) Ohio, (9) South Dakota, and (10) Wisconsin. These 10 states planted 71.7 million acres of the total 92,888 million acres of corn in 2007.

 B. Worldwide, the United States accounted for 38 percent of the world’s corn production. It was followed by China (21 percent), Europe (8 percent), and Brazil (7 percent).

 C. The major export markets for corn grown in the United States are Japan (29 percent), Mexico (17 percent), Taiwan (8 percent), and South Korea (8 percent).