By late summer, most of the corn in America is head high and bristling. The stalks stand shoulder to shoulder like an army without rank, their sharp-edged, swordlike leaves forming a nearly impenetrable wall. A modern cornfield would have rebuffed Cary Grant in “North by Northwest” because there are no rows to speak of, only a dense lattice of intersecting spears. This corn – grown by the tens of millions of acres – has been genetically engineered, altered by having stacks of apparently desirable traits wedged into its genetic code. Saving the kernels of engineered corn in the fall to plant in the spring is both illegal, because of company patents, and largely irrelevant, since the plants they yield, which contain a packet of foreign genes, won’t necessarily resemble the parent crop. Nearly all the corn you see anywhere in our nation of corn is this year’s model, new and, so they say, improved.

Genetically modified corn is the path industrial agriculture has chosen – a profoundly controversial one. But a growing movement of gardeners and small farmers is keeping alive the genetic diversity that modern agriculture has rejected.

It’s a movement committed to growing and saving heirloom seeds, traditional varieties that, in many cases, have only narrowly survived.

In July, I visited a cornfield that gave survival a new meaning. It was on the Tuscarora Reservation, just northeast of Niagara Falls, N.Y. A modern commodity corn farmer would have laughed at it from the air-conditioned cab of his $350,000 combine, and even a backyard gardener growing sweet corn would have found it puzzling. The rows were set wide, and the soil had not been hand-weeded, sprayed or “cultivated,” which is the name for mechanical weeding. It had been a dry season in the Niagara frontier. The cornstalks were waist high, and the leaves seemed to have opened their arms to the sun in a delicate arc. The tassels – the organs of germination – had barely begun to form.

I had the advantage of knowing what this field – part of a Tuscarora Community Supported Agriculture project – would eventually yield; otherwise I, too, would have been doubtful. Earlier that morning, I’d stopped by the office of the Tuscarora Environment Program. Neil Patterson Jr., the director there and co-author of a pictorial history of the Tuscarora Nation, handed me an ear of Tuscarora corn.

You may be thinking of Indian corn, picturing the ornamental, multicolored ears that seem to have been bred for Thanksgiving centerpieces. Or if you’ve spent time in the Southwest, an ear of Hopi blue corn may come to mind.