All around the happy village
Stood the maize-fields, green and shining,
Waved the green plumes of Mondamin,1
Waved his soft and sunny tresses,
Filling all the land with plenty. . . .
And the maize-field grew and ripened,
Till it stood in all the splendor
Of its garments green and yellow,
Of its tassels and its plumage,
And the maize-ears full and shining
Gleamed from bursting sheaths of verdure.
—from “The Song of Hiawatha,”
by Henry Wadsworth Longfellow
When speaking of corn, for most Americans, the first thing that comes to mind will almost certainly be sweet corn, perhaps followed by popcorn. This response may be different for those who rely on, grow, or study the other types of corn, but say “corn” in most nonfarm locations in the United States, and people generally say something along the lines of, “It’s my favorite vegetable” or “I love corn on the cob.” However, there is a lot more to the corn story than sweet corn.
There is, in fact, a tremendous amount of diversity in the world of corn. There are different corns for different purposes, climates, tastes—and, in some cases, there are differences just because corn diversifies so easily. However, taxonomists have established some order, so discussions about corn don’t descend into chaos. Surprisingly, in the face of such diversity, there is only one species of corn—Zea mays. Therefore, the many varieties all have much in common, and commonalities will be examined first.
Essentially, corn is big grass. It grows faster than other grasses. Its large leaves make it better at capturing sunlight than other grasses. It is incredibly efficient at converting heat and light into food.2 So it’s really impressive grass, but it’s still grass.
Like rice, wheat, oats, and other related grains, corn is classified as a cereal grass. Because corn became important to farmers long before scientists started studying it, almost everything on the corn plant has a correct technical name plus a name that everyone uses. For example, as a grass, the central structure is the stem, but it would be hard to find an American who doesn’t refer to it as a stalk. The exuberant golden plume that tops the stalk is the male inflorescence, more commonly called the tassel. The female inflorescence is the ear. People refer to corn kernels, but they are more technically grains—or, even more technically, among biologists, caryopses. The ear is cradled by a close-fitting sheath of leaves, which are generally called husks. However, the rest of the leaves on the cornstalk do share a name with other grasses—blades.
When the tassels flower, they shower abundant pollen (2 to 25 million grains of pollen from one tassel)3 on the plants around them. (Corn actually produces far more pollen than any other cereal grain.)4 The pollen ideally finds its way to the “soft and sunny tresses” of golden corn silk (called styles, which are the necks of the pistils) that dangle from the open end of the enrobing husks. Every would-be kernel of corn is attached to one of these styles and must be pollinated to develop. However, as clouds of pollen billow into the air, it is possible for pollen from different plants to reach the awaiting silks, so every kernel on an ear could potentially have a different “father.”
An ear of corn may have anywhere from four to thirty rows of kernels, depending on the variety, but it will generally be an even number.5 The grains are attached to a central shaft called the rachis, though in corn, the exceptionally large and sturdy rachis is called a cob.6 The kernels themselves, like all cereal grains, have three key components: the germ, which is the embryo of a future plant; the endosperm, which is the starchy “filler”; and the pericarp, or hull.
The endosperm makes up the majority of the corn kernel: about 75 percent. Its job is to supply food to the plant between germination and the appearance of the first green leaves, at which time the plant can start making its own food. The abundance of endosperm makes such genetic traits as color and starch characteristics fairly evident, which endeared corn to scientists early on.7 Depending on the type of corn, the endosperm can be mostly starch or a blend of starch, protein, and fats. The makeup of the endosperm is a key factor in classifying corn, as well as in determining its culinary potential.
The pericarp is there for protection. Interestingly, while the endosperm and embryo will carry genetic material from both mother and father, the pericarp is pure mom—so a bit like a womb or the shell of an egg. Because of this—the female material surrounding the embryo and endosperm—the grain is technically considered a fruit. The pericarp may be transparent, but it can also be the carrier for the reds, purples, and browns associated with decorative Indian corn.
The embryo is just that—a miniature plant-in-waiting. The embryo, or germ, can be seen on the flattened side of a corn kernel. In addition to being a potential future plant, a part of the embryo known as the scutellum is also where most of the plant’s fat is stored.8
Native Americans’ success at transforming teosinte and then diversifying corn were made possible by another of this plant’s quirks: a jumping gene. A jumping gene is a piece of DNA that can insert itself into the control region of another gene and make it change. This doesn’t happen in many organisms, and in fact corn was among the first plants to show that jumping genes, also known as transposable elements, can actually change the development of an organism.9 The part humans have long played in the equation is noticing the changes, recognizing the possibilities offered by the changes, and then breeding to keep new traits developing, rather than letting them vanish.10
Scientist and corn researcher Dr. Stephen P. Moose admires the Native Americans’ accomplishments. “We have never been able to make changes as dramatic as what the early breeders did in changing teosinte to corn. We’re just tweaking corn now, but we haven’t transformed it like they did.”
Farmers and scientists may not have transformed corn, but after five hundred years of selective breeding and more recent “tweaking,” varieties now run into the thousands—more varieties than any other crop species. There are so many varieties, in fact, that grouping them systematically is a daunting task. In the Americas alone, taxonomists have identified roughly 300 families that help them sort all the varieties of corn.11
Corn plants can be two feet tall or twenty. They may have eight leaves or forty-eight. Ears of corn can be anywhere from a few inches to two feet in length.12 Color differences can be dramatic, from white or yellow to bronze, red, purple, blue, and black.
It was a gentleman named E. Lewis Sturtevant who, just over a hundred years ago, got us started on the road to categorizing corn. Sturtevant, who was the director of the New York Agricultural Experiment Station, wrote in 1878, in a book titled Indian Corn, “The varieties of maize are numberless, and we know of no adequate attempt to reduce them to a system whereby they may be intelligently classified and described.” (And since Sturtevant wrote that, the numbers of varieties have continued to increase.) As Sturtevant noted in his Notes on Edible Plants, of the 307 varieties exhibited to the Massachusetts Board of Agriculture in 1880, “these are but a tithe of the various kinds that could be gathered together from the various regions of the globe.”
Sturtevant wasn’t starting from scratch. People had already divided up corn by starch content and use. As he noted in Indian Corn, “Everyone knows that there are four kinds of corn—the pop corn, the flint corn, the sweet corn, and the dent corn.” But that was just the beginning. By 1884, when Sturtevant published Maize: An Attempt at Classification, he had added two more kinds, or races, as he called them: flour (or soft) corn and pod corn. He had also identified a wide range of variations in each of the races or types of corn, so that anyone might be able to categorize corn even as new varieties emerged.
However, as noted by geneticist Edgar Anderson, Sturtevant’s efforts were “something like an attempt to classify the peoples of Europe on nothing but eye color.” Sturtevant himself realized that his system had its limitations, based as it was on such a small number of attributes.13 But it was a start, and, though a bit oversimplified, it was useful. Despite the shortcomings of the system, it was fairly universally adopted, and from seed catalogues to scholarly treatises, corn varieties are generally slotted into one of these six races.
While the names of the categories were relatively new, Sturtevant points out that the races themselves are “from a distant antiquity.” In other words, Native Americans had done the big work of creating the major differences. Sturtevant would simply attempt to identify those differences and show how everything else related. As with all types of categorization, there are many layers and refinements, as well as frequent overlapping. Sturtevant’s work was peppered with subraces and exceptions, as well as myriad varieties, but it did offer a framework.
It is also common to hear people refer to field corn. This is not a different race, but rather a purpose: field corn is corn that is grown to be processed (cornmeal, cornstarch, ethanol, etc.) or fed to animals. When people talk about field corn, it is usually contrasted with popcorn and sweet corn. Field corn, also known as grain corn or commodity corn, can be any of the races of corn other than sweet or pop, though in the United States, and especially in the Midwest, any mention of field corn is usually referring to yellow dent corn. The vast majority of corn grown in the United States is field corn.14 About the only times a person would be eating whole grains of field corn would be if he or she were enjoying hominy/pozole, parched corn, or corn nuts—or lived on a farm and had ready access to green corn.
So what is it that defines these races? In most cases, it’s about the starch.
Flour corn, also known as soft corn, has an endosperm composed almost entirely of soft, loosely packed starch. All corn has a little soft starch, but in flour corn, that’s pretty much all there is.15 As a result, the texture is mealy and the kernels are soft and easily ground. The cornmeal produced from flour corn has a finer, more floury texture than meal produced from other races of corn.16 Flour corn made its way up Mexico’s west coast about two thousand years ago, spreading into the American Southwest. It is still grown and used by Native American groups in this region.17 The blue corn that is most readily identified with the Southwest, especially Hopi culture, is a flour corn.18 It continued to spread northward and onto the Great Plains, and was used by Native Americans as far north as Iowa.19 The flour corns have a longer growing season than the flints, so they don’t do well above latitude 40° North. Their tall stalks make them liable to suffer wind damage, but they are excellent for the type of intercropping practiced by many Native Americans, acting as trellises for the beans that traditionally accompanied corn.20
Flint corn, as the name suggests, contains mostly hard starch. Flints offer several advantages. They mature quickly, so they can be grown in areas with shorter summers. They germinate well in colder, wetter soils and are therefore suited to mountainous areas, such as those of New England. In addition, the flavorful meal made from flint corn stores well, as it doesn’t absorb moisture as readily as corns with more soft starch.21
Flint corn moved up the eastern side of Mexico, spreading into the eastern woodlands and northward into what would become New England. Flint corn is the only race of corn that archaeologists have discovered in the East,22 which means it would have been flint corn that rescued both those settling Jamestown in 1607 and the Pilgrims in 1621. However, while there was only flint corn in the East, flint corn was not limited to that region. It spread inland as far as the northern prairies.
Flint corns come in a tremendous range of colors: red, black, purple, orange, mahogany, yellow, blue, white. The ears produce fewer kernels than other types of corn—a tradeoff that gains this corn its speed in maturing.
Developments during the twentieth century pushed flint corn out of much of its traditional range, at least in the United States (it is still popular in other countries at latitudes similar to New England’s, from Japan to Italy).23 However, it is not vanishing even here. Organizations such as Slow Food have stepped in to protect some of the most important varieties.24 Elsewhere, people ranging from small farmers to finicky epicures to food historians keep favorite varieties alive. Because of the higher protein levels and pigments, flint corns have richer flavor. They also have more body and texture than flour corns. They are pretty much the gold standard for everything from polenta to porridge to johnnycakes.25 Still, flints are in the minority in the United States. Flints do well in gardens, and there are still farmers who grow flint corns, so flint corn is available, but for most people, the Internet is the most likely source for flint corn—seeds and ground meal.
Dent corn has a combination of hard and soft starch. The hard starch is on the sides of the kernel, which helps the kernels keep their shape as they dry. However, the soft starch that fills the heart of the kernel to its top shrinks as the kernel dries, pulling the top downward. This shrinking starch creates the depression, or dent, on the top of each kernel that gives this race its name.
Dent corn was one of the last races to emerge in Mexico. From there it moved northward onto the prairies of the Midwest. Archaeologists have uncovered examples of dent corn at many of the prehistoric sites in this region. However, even though flint corn moved from the East across the northern prairies fairly early on, dent corn appears not to have made it to the East until the 1700s.26
Dent corn has now become nearly ubiquitous in the United States. Most of what one reads or sees about corn in the media—ethanol, cattle feed, corn syrup—is about dent corn. That’s because most of the corn grown in the United States is dent. In fact, varieties of yellow dent corn are so dominant across the Midwest that they are often called Corn Belt Dents.
If one buys a commercial brand of cornmeal at the supermarket, it will be made from dent corn. Dent is softer and easier to grind than flint, and the flavor is more delicate than that of corns with more hard starch. The meal from dent corn is closer to that of flour corn and produces cornbread with less body but smoother texture than that made from flint cornmeal.
Much of the discussion in the rest of this book will be about dent corn, because it is the most economically important race—the one known as King Corn. Popcorn and sweet corn will also be covered, because they are the types with which most people have a direct relationship, but they are minor players compared to the dents.
Sweet corn is the result of a genetic mutation. All corn is sweet when immature, but sweet corn has a higher percentage of sugar than other corns, and the process of converting sugar to starch—the mutation that defines sweet corn—is dramatically slower. With other races of corn, the conversion begins as soon as the corn is picked. With sweet corn, one has a bigger window of opportunity—enough time to get it to market and still have it be sugar-sweet.
While sweet corn existed before First Contact, it didn’t have much presence in the United States until the 1700s, and then it moved into the mainstream from the northeast, rather than up from the south. So sweet corn is comparatively new on this continent.
Sweet corn has soft kernels, which makes it easy to eat but also results in very wrinkled grains, if the corn is allowed to mature. Gardeners who are considering buying seeds to grow their own should be aware that being wrinkled is actually one of the defining characteristics of sweet corn seeds.27 As with other races, there are many varieties, including the new super sweets (which are not actually sweeter, but simply stay sweet longer). Peruvian corn, also known as choclo, is a variety that has begun appearing in Hispanic grocery stores in the United States. This import is starchier and has larger kernels than the sweet corn varieties common in North America.
Popcorn is the smallest of the corn races. Like flint, its starch is hard. Not too surprisingly, its defining characteristic is its ability not merely to pop, but also to produce a reasonable “flake” (that soft, snowy, fragrant explosion of starch that is the point of preparing popcorn). It is actually possible to pop flint or dent corn, though the flake is much smaller.28
Popcorn is the oldest of the races of corn still cultivated. Popping is actually a characteristic that popcorn shares with its progenitor, teosinte. Popped teosinte, in fact, looks pretty much like popped popcorn. Some people hypothesize that the stalks and leaves of teosinte were eaten first, and the tough kernels just got too close to the fire. When the kernels exploded, early Indians discovered that they were worth eating.29
While popping is, economically and culinarily speaking, this corn’s chief virtue, it can also be ground into meal. In fact, popcorn can be used pretty much anywhere flint corn is used.
Pod corn, which Sturtevant also referred to as husk corn, is a variety in which individual grains are enclosed in husks.30 These leaf-like husks, known as glumes, are in addition to the husks that enclose the ear, and they give an ear of pod corn a strange, shaggy appearance, as though someone were making imitation corn out of straw. Pod corn is a fairly ancient mutation of corn, known since pre-Columbian times. At one time, it was hypothesized that pod corn was an ancestor of maize, but the most recent research has laid that theory to rest. It’s just a form that took a different direction from the other five races.31 Pod corn is something of an outsider, and some lists don’t include it, offering only the first five races of corn. Though venerable, edible, and still available, it is considered mainly a curiosity, primarily of interest to those doing research in corn genetics. Pod corn is not grown for commercial use.32
On top of these, a number of specialty corns have been bred more recently, variations that are ideal for specific purposes. Waxy corn is probably the most important and is sometimes listed as if it were one of the races. Others include high-lysine corn, high-oil corn, and high-amylose corn. The high-lysine corn has more of the essential amino acids lysine and tryptophan, and it has been used to improve nutrition in poorer countries. The other specialty varieties are important in food processing and in a wide range of other applications. However, they won’t be appearing at local grocery stores.33
Among the thousands of varieties of corn, there are places where the lines among races get blurred. But the above categories are the framework on which most discussions of corn are hung.
(By the way: the plant called broomcorn is not corn at all. It is actually a type of sorghum—so it is related only distantly, in that it is another grass. However, though the corn part of the name is misleading, the broom part is not. Brooms have long been made from the stiff bristles of this plant. But broomcorn is not corn.)
Corn was the perfect plant for people living on the edge of the frontier. It was, in fact, vital to survival—because corn is unique among grains in that one can start eating soon after it starts growing. When one is a pioneer on the edge of nowhere, that can be a huge advantage. Like the Native Americans from whom they adopted much of their corn culture, pioneers picked ears of corn when they were still tiny. These baby ears could be eaten, cob and all. So food from corn was available very early in the growing season. Generally speaking, the baby ears being picked would be “extras” plucked from stalks that had developed multiple ears. That way, settlers still had a crop growing, even as they munched on baby corn.34 Any of the different races of corn can be harvested at the baby-corn stage.35 If not eaten immediately, they could be pickled and saved for winter.36
The next important stage would be the milky stage, when kernels are juicy and sweet and the starch looks milky when the kernels are cut. Corn picked at this stage is called green corn, because it is immature, not because it is green in color. Any race of corn can be picked at this stage and enjoyed in any manner one would eat sweet corn, as all kernels are sweet in the early stages of development. So roasted, boiled, fried, or added to soups or chowders, this was a great treat during the summer and could keep a family fed for weeks, as they could pick corn as needed. (However, unlike sweet corn, green corn starts losing sweetness almost immediately after being picked, so preparation was always as swift as possible after the ear had been plucked from the stalk.)37
Finally, there was the fully mature corn. This is the stage at which corn would be dried and ground, with the amount of work needed depending on the type of corn grown. Flour corn is the easiest to grind, followed by dent, but many thought (and some still do) that the richer flavor of flint corn or popcorn made the extra work needed to grind them worthwhile.38 Some of the dried corn would be saved for seed, of course, and much would be fed to the animals, but this is the stage that brought food to the table for every meal. Cornbread, johnnycakes, corndodgers, porridge, pone, cornmeal mush, corn pudding, hasty pudding, hominy, fritters, grits, and more, varying by region or background of the person preparing the meal, were the mainstays of pioneer diets pretty much all year.
On top of all that, cornstalks are fairly sweet and could be chewed for a quick lift while working in the field. This should probably not be too surprising, as corn is a close cousin to another useful grass: sugarcane.
Diversity is one of the identifying characteristics of corn. With thousands of varieties for a wide range of locations, it is an economic and culinary powerhouse. With its ability to provide food at multiple stages of growth, it was a boon to pioneers. It was the crop that made it possible to open up the Middle West.