Corn is the name that we use here in the United States as well as in Canada and Australia for the
grain maize. In England, as well as most of the English-speaking world,
the term "corn" is a generic term for cereal crops, such as wheat, barley, oats,
rye and of course, maize.
In Native American lore, maize was one of the
crops that made up the "three sisters." Along with beans and squash, corn
was planted and grown together, supporting each other in their life cycle and
providing a very balanced diet of carbohydrates, proteins and vegetable fats to
their cultivators - Click Here for the Rest of the Story.
Native American corn was the genetic foundation of all other corn varieties. "Indian" corn is rarely grown in the garden today. Columbus was one of the first Europeans to see maize or corn. The Pueblo Indians were raising irrigated corn in the American Southwest when Coronado visited in 1540. The settlers at Jamestown were taught how to raise it in 1608 and in 1620, it helped to keep the Pilgrims alive over winter. Corn cobs were found in Tehucan, Mexico that date back 7000 years.
Most people now associate corn for eating with modern sweet corn varieties that incorporate specific genes to increase or enhance sugar quantities and shelf life. Other types of corn can be eaten like sweet corn when it is young, but are usually grown to maturity, dried and used for flour and meal.
Corn is probably the most diverse grain crop. Both man and nature have selected traits that can roughly be classified by the characteristics of their kernels -- flint, flour, dent, pop, sweet, and waxy.
Flint corn typically has hard seed coats that with rounded, smooth, kernels consisting of soft starch covered by horny starch. Many Indian corn types are flint type. The are well suited for making good quality corn meal or ground and used for livestock feed.
Dent corn has hard, "flinty" sides composed of horny starch, with soft starchy tops and cores that allow the ends to collapse or "dent" when the corn dries. Varieties of dent corn are the most widely grown types in the United States and used for oils, syrups, grits, meals, flours, bio-fuel, silage, and livestock feed.
Flour corn is composed almost completely of soft starch with thin seed coats. Kernels are round and smooth like flint corns. In these modern times, they are primarily used for making corn flour.
Historically however, flour corn was also raised and used for parching. Parching is a process whereby the kernels are gently roasted until they slightly expand, the seed coat splits and the kernels become soft. Parched corn was used as a snack or trail provision and could last several months if stored properly.
You can parch just about any flour corn variety but some are better suited than others. White and yellow varieties are typically the least flavorful parched. Try using the more colorful varieties as then tend to be neither bland nor strong tasting. Many are sweet with flavors that develop further as they are chewed.
Popcorn is one of the oldest forms of corn and can be generally classified into two types, pearl or rice, based on the physical shape of the kernels. Popcorn usually has small kernels that contain a high percentage of horny starch - even more than flint-types. This causes them to violently burst and expand upon heating.
Sweetcorn is the result of a natural spontaneous mutation of field corn that occurred sometime before recorded history. Predating the arrival of Europeans in North America, it was cultivated by several Native American tribes. A variety named 'Papoon' was raised by the Iroquois, and subsequently by settlers, by 1779.
Sweet corn is now primarily grown for fresh, canned and frozen consumption and not used for flour or
feed. Its genetic makeup is such that it accumulates sugars while the kernels are immature.
By the way, the "baby corn" that you use on salads are simply immature, unfertilized ears that have been harvested and sometimes pickled.
 The horny starch is found on the back and sides of the grain lying next below the horny gluten. It does not consist of pure starch but contains considerable amounts of other substances, especially protein. In an examination of the grain with the unaided eye. the horny glutenous part and the horny starchy part are not readily distinguished from each other, the line between them being somewhat indefinite and indistinct. Together they constitute the horny part of the grain.
Source: "Maize: Its History, Cultivation, Handling, and Uses . . ." by Joseph Burtt-Davy, page 661, 1914.
If you are simply growing corn to eat, you do not need to worry about the corn
varieties that you growing intermingling their genetic material in random
fashion. You are raising food and not seed.
however, you are wishing to save seeds for future planting, considerations must
be made to prevent cross-pollination. To
maintain the genetic diversity of a cultivar, seed should be collected from a
minimum of two hundred (200) plants. Maize uses the wind to distribute its pollen from the tassels of one plant to the developing ears of another.
maintain the genetic purity of a cultivar, that is, keeping the variety
true-to-type, great isolation distances are required. Depending on climate
and geographical features in your area, separating varieties by up to one mile
An alternative to isolation distances is hand pollination. It is a time
consuming effort but not inherently difficult. The following video from
the University of Wisconsin is a good tutorial on the process: