"High Majestic Fooling" (Everything You Ever Wanted to Know About Corn Sex)
by Emily Gatch

     There was a high majestic fooling
     Day before yesterday in the yellow corn.
     And day after to-morrow in the yellow corn
     There will be high majestic fooling.
     ...
     Some of the ears are bursting.
     A white juice works inside.
     Cornsilk creeps in the end and dangles in the wind.
     Always—I never knew it any other way—
     The wind and the corn talk things over together.
     And the rain and the corn and the sun and the corn
     Talk things over together.

     —From Carl Sandburg's poem "Laughing Corn" (1918)
     Permission to use granted by: Harcourt Inc. (June 28, 2005)

"High majestic fooling?" I'm no poet, but it seems obvious to me that Carl Sandburg is talking about corn sex. As we head into high summer, backyard rows of sweet corn and the endless acres of field corn that stretch across the country will all begin a wild carrying-on. I'd like to take a closer look at what actually happens when the wind and the corn start talking things over. My introduction to this topic was memorable but decidedly unexciting: like many kids in the rural Midwest, my first summer job was detasseling corn for a hybrid seed company. Detasseling—walking rows of corn pulling out the male part known as the tassel—is essentially a highly controlled interference with the intimate affairs of corn plants. To explain this process further, as well as understand why it's not uncommon to find a few starchy kernels on an ear of sweet corn, a brief botany lesson is in order.

Summary of Corn Types Dent: soft inner endosperm surrounded by hard outer endosperm—try Oaxacan Green for great tortillas and cornbread Flint: similar to dent but without softer inner endosperm—try Wachichu Flour: soft endosperm suitable for grinding—try Hopi Pink, Mandan Red Sweet: newest type, characterized by high sugar content when immature—try True Gold, Golden Bantam Pop: most ancient type, with hard endosperm that explodes when heated—try Dakota Black Parching: similar to popping but only "fluffs" slightly—try Supai Red or Magenta for a great snack food. For a more thorough explanation of these categories, and for an excellent history of corn evolution, read Steve Peters' article "The History and Evolution of Corn" in eNewsletter #43.

A typical flower contains male structures called stamens and a female structure called the pistil. In some cases, male and female parts are housed in separate flowers, a condition defined as "imperfect." The formation of a fruit occurs after pollen released by the stamens fertilizes the egg(s) contained within the ovary of the pistil. A plant species can be either self-fertile, meaning fertilization is possible between pollen and eggs produced by the same plant, or self-sterile, meaning cross-pollination between two different plants (still within the same species) must occur for successful fertilization. In many plant species, including corn, a combination of self- and cross-pollination can occur.

The ripening of a fertilized ovary is what produces a "Black Beauty" zucchini or a "Martian Giant" tomato. The seeds within a fruit, whether a tomato or a summer squash, each contain an embryo in which the genes of the two parent plants mingle and await a new growing season to express themselves. This is the simplest explanation why, for most crops we grow in our gardens, isolating different varieties from each other is necessary only if we want to save seed for next year and have those varieties "breed true." The outcome of a cross between a Yellow Crookneck squash and a Black Beauty zucchini (both Cucurbita pepo and thus capable of inter-breeding) is contained within the seed, not in the delectable tissues of maternal origin surrounding and protecting the seed.

Corn, along with other grass family members such as wheat and rice, has a slightly different reproductive story, which has practical implications for growers and eaters. Corn has imperfect "flowers": the tassel of a corn plant is the male structure where pollen is produced; the ear with attached silks is the female structure. Each silk connects to an ovary, the site of a future kernel, and must be traversed by a pollen grain in order for fertilization to occur. Every kernel of corn on an ear is thus the product of an individual pollen-meets-egg event. Enormous amounts of pollen are shed from each tassel to ensure that no silk is missed; to experience this phenomenon, simply walk through a corn field at pollen-shed and emerge coated in yellow dust.

A corn kernel contains an embryo surrounded by endosperm, a starchy material derived from a separate union of male and female genetic material that occurs as part of the fertilization process. This endosperm forms the bulk of the kernels that we savor on an ear of corn, but its true reason for existence is not our own nourishment but that of the embryo as it germinates to form a new corn plant. The seeds of vegetables such as tomatoes and squash also contain the equivalent of endosperm incorporated into their cotyledons, the fleshy seed leaves that appear first as the seed germinates; however, since the seeds of these vegetables aren't the most noticeable part of the eating experience, we don't pay too much attention to them unless, of course, we're seed savers or plant breeders. In that case we're very concerned with the specific cross that produced both embryo and endosperm so that we can preserve the integrity of different varieties or attempt to breed new varieties.

With sweet corn, as we have just seen, the endosperm is what we're eating: that's why we care about the identity of the parent plants before we even get around to saving seed for next year's crop. The presence of what are called "sugary" genes in sweet corn varieties results in levels of sucrose in the endosperm that are double those found in a typical dent corn, for instance. Because the endosperm expresses genes contributed by both parents (keep in mind that the "flesh" of typical fruits is mostly of maternal origin), it's possible that a nearby planting of dent, flour, or ornamental corn might result in some furtive cross-pollination and the surprise appearance of a few "rogue" kernels that are not typical of the variety you planted. It's nothing to be overly concerned about, and certainly no reason to limit the diversity of corn types that you cultivate; if you can plant sweet corn and flour or ornamental varieties on opposite ends of the garden, great. If not, as you start shucking for the season's first platter of sweet corn you'll have a few reminders of the complex and fascinating "carrying-on" that went on out in the backyard.

If you are saving seed for next year's crop and want to maintain the purity of several different corn varieties, avoid unwanted crossings between varieties by maintaining an isolation distance of one mile. Another option is to isolate temporally by scheduling planting times to ensure that the tasseling periods of each variety are at least two weeks apart. The latter strategy is more challenging because maturity dates are affected by regional weather conditions, but in a small garden it might be the best option. Other strategies for avoiding cross-pollination for home-scale seed saving include selecting long- and short-season varieties to stagger tasseling times, or placing paper bags over the ears before the silks appear; then hand-pollinate by breaking tassels from many plants and "dusting" it over the silks. If you choose the latter, it helps to pollinate several times, avoiding windy weather when rogue pollen might be in the air.

If all this botanizing detracts in any way from the thrill of that first feast of July sweet corn, refer back to the words of Carl Sandburg, poet of the Illinois prairie. He assures us that the wind and rain and sun and corn are "talking things over together," ignoring our best efforts to listen in.

Emily Gatch
Greenhouse Coordinator and Assistant Seed Cleaner

Helpful References (available in print and online):

How a Corn Plant Develops: Special Report No. 48, Iowa State University Cooperative Extension Service. Ames, IA. Reprinted June 1993. http://maize.agron.iastate.edu/corngrows.html

Specialty Corns: Guide H-232, George W. Dickerson, Extension Horticulture Specialist. New Mexico State University Cooperative Extension Service. Las Cruces, NM. Reprinted February 2003.http://cahe.nmsu.edu/pubs/_h/h-232.pdf

Photo captions: (1) Sexy corn silks (2) Diagram of a corn kernal (3) A romantic corn moon (4) Heavy corn tassels