Why Do We Grow Yellow Dent Corn?

This column was published originally in the Ontario Farmer in 2004. Reproduced here with permission.


For large parts of the world – notably Mexico, most countries in Latin America and Africa where corn consumption often dominates human diets – corn kernels are white. But at least 99% of North American grain corn is yellow – indeed, almost always yellow dent corn. It’s also mostly yellow in Europe and Asia. Why is that?

As it turns out, it was not always so. And the reason why that’s now true is largely a fluke of history. Here’s the full story.

From its origins about 7000 years or so in Mexico, corn had diversified dramatically before Columbus’s arrival in the New World. There were at least 300 different corn races (most still existent in local production or ‘gene banks’). Kernels ranged from three millimetres to more than three centimeters across; kernel textures varied from very hard (flint) to very soft (floury), and there was every colour possible – black, brown, purple, red, green, orange, yellow and white – often with several different colours on the same kernel. Hopi Indian corn still grown in Arizona is typically blue.

Strangest of all was/is pod corn where the normally small glumes (farmers often call them ‘red dog’) at the base of kernels are so large that they cover the entire kernel – like the glumes of wheat.  Though once considered a relic of wild corn, we now know it is only an interesting mutant. William Emerson wrote in 1878 “a species of corn has a separate husk for each kernel” because of “the efforts of the plant to resist the coldness of the climate”, a fascinating though incorrect explanation.

Number of ears per plant also varies – from one at virtually every leaf axil with Argentinian pop corn, to only one per plant with modern corn hybrids grown at standard seeding rates. For more info on corn races, see chapter one by William Brown and Major Goodman in Corn and Corn Improvement.

When colonists first reached present-day Canada and the eastern United States, aboriginal farmers mainly grew two races of corn.  In the south was ‘gourdseed’ with soft, white, long, thin, deeply indented kernels in up to 48 kernel rows on relatively short, squatty cobs. In Canada and the northern US was ‘flint’ corn with large, round, hard kernels in eight to twelve rows on long narrow cobs.  Flint kernels were mostly white or yellow but other colours were common.

The chance discovery of an infrequent red-kernelled ear at a husking bee meant a gift of already husked ears from other bee participants in aboriginal times – or a kiss from lad or lass of choice (or a round of whiskey) during colonial days.

There was some aboriginal mixing of corn north and south.  When the Tuscarora Indians moved from the Carolinas to New York State in about 1720 to become the final member of the Six Nations, they brought their soft, white corn.  When they later moved to Ontario in about 1784, the Tuscarora white corn came too.

The first European settlers grew the local native corn, but intermixing occurred as settlers or their descendants moved up and down the Atlantic seaboard, and westward.  Many of the early settlers in southwestern Ontario came from the US and brought corn seed with them. Gourdseed and flint corn were both grown in Essex and Kent counties (the most southwesterly counties in southern Ontario) before 1800.

As the annual selection of ears for next-year’s seed continued – sometimes by plan and sometimes at random – there arose hundreds of corn varieties. Sometimes the same variety was grown under many different names. I’ve read one tale from southwestern Ontario where customers could order several different varieties of seed corn at the store front, but the seed all came from the same barrel or two at the back.

In 1751, botanist Peter Kalm described two main types of corn growing in the Atlantic colonies and Canada – “big corn” (or full-season corn), and early-maturing ‘small’ or ‘three-month corn,’ both with a wide range of colours. But a century or more later, with corn farming well established west of the Allegheny-Appalachian Mountains and expanding further, there were many more names. One of the most fascinating was Mammoth White that produced ears typically more than 13 inches in length and circumference.

Natural cross-pollination between flint and gourdseed plants grown together resulted in offspring plants with corn kernels, which were intermediate in shape and structure between the two parental types.  This became known as dent corn.

There were lots of different varieties in Ontario too. Mr. Iler, an Essex County farmer, reported to the Ontario Agricultural Commission in 1880, “the varieties generally grown are the large yellow and white Gourd Seed, though the yellow and white Flint are also grown.” In the early 1900s, some popular Ontario varieties were Wisconsin 7 (white dent), Bailey (yellow dent), White Cap Yellow Dent (yellow dent with white caps), Golden Glow (yellow dent), Longfellow Flint (yellow), Salzer’s North Dakota (white flint), Silver King (white dent), and Early Leaming (yellow dent).

Nap King of Pain Court, near Chatham Ontario, said that when he started in the corn seed business in 1934, most of these were still popular in Ontario, as was Bloody Butcher, a red dent variety. Yellow dent corn was most common, but white corn was grown for corn flakes and other milled products.

Among the many North American corn varieties, a few proved to have much greater long-term significance.

Isaac Hershey, a Mennonite farmer in Lancaster County, Pennsylvania spent many years blending a late, rough-eared gourdseed-type corn with an early maturing flint.  Natural cross-pollination and selection of desirable ears at harvest for next year’s crop led to the creation of a new yellow dent variety called Lancaster Sure Crop.  It gave consistently good yields, even though known for its rough ears and lack of uniformity.  This variety later became a major source of inbreds.

Robert Reid moved west from Cincinnati to Peoria, Illinois in 1845, and brought with him seeds of a reddish gourdseed variety called Gordon Hopkins originally from Virginia. Because of its more southern origins, this variety matured poorly in its first year at Peoria.  Seed quality was poor and the stand emergence thin in the spring of 1847. So Mr. Reid filled in the gaps in early June with seeds of a short-season flint variety called Little Yellow.  Reid liked the resulting yellow dent ears created by natural cross-pollination between the two original varieties, and the yields were good. His son, James, continued to improve the new blended variety, called Reid’s Yellow Dent.

In 1893, Reid’s Yellow Dent won first prize at the Chicago World’s Fair.  Reid’s variety was subsequently used as the genetic base for many other yellow dent varieties.  These included the widely grown Funk’s Yellow Dent produced by Eugene Funk, founder of Funk’s Seeds at Bloomington, Illinois, perhaps the world’s largest seed corn marketer in the early1900s.

But the greatest push came from P. G. Holden, a Michigan farm boy, who worked briefly for Eugene Funk and was then hired by Henry C. Wallace in 1902 to join Iowa State College. (Wallace’s son, Henry A., later founded the Pioneer Hybrid Corn Company.) Holden crossed Iowa many times in a railcar called the ‘Corn Train’ championing corn improvement and the production of Reid’s Yellow Dent.  His promotion was so effective that Reid’s became the dominant corn in Iowa, just as other varieties derived from Reid’s variety were becoming popular in other Corn-belt states. And because Reid’s corn was yellow dent, most Midwest corn became yellow dent, even though white corn had been just about as popular before then.

Reid’s Yellow Dent became a major source of early corn inbreds for hybrids. Early Midwest corn hybrid breeders learned early that inbreds developed from Reid’s crossed well (good hybrid vigour) with inbreds from Lancaster Sure Crop. The variety Iodent, developed by Iowa State College (now Iowa State University) in the early 1900s from Reid’s Yellow Dent, is still an important original source of corn inbreds. Newer inbreds are mostly earlier maturing, higher yielding, more pest resistant, with better stalks and grain quality, but are still yellow dent.

Hence, ‘corn’ as it is now grown in North American, usually means yellow dent. White corn is grown mostly as only a milling crop. But if Robert Reid or Isaac Lancaster had started with white varieties, or if a white corn variety had won at Chicago, or if Holden had promoted a white corn variety, or if the first successful Midwest inbreds had been white, most North American would likely be white today.

(They’re virtually identical nutritionally. Yellow corn obviously is higher in the yellow-coloured beta-carotene, a precursor of vitamin A. Important as that is in parts of the world where grains dominate human nutrition, it’s largely non-significant in North American diets containing many other sources of beta-carotene.)

Such are the quirks of history.

Some references:

Crabb, Richard. 1992. The Hybrid Corn-Makers, Golden Anniversary edition. West Chicago Publishing Company.

Fussell, Betty. 1992. The Story of Corn. University of New Mexico Press.

Kalm, Peter. 1751. Description of Maize. Translated by M. Oxholm and S. Chase from original in Swedish. Economic Botany 28:105-117, 1974.

Pegg, Leonard. 1988. Pulling Tassels. Blenheim Publishers Ltd.

Wallace, Henry A. and William A. Brown. Corn and its Early Fathers, revised edition. 1988. Iowa State University Press.

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