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| The Sierra de Manantlán mountain range in western Mexico, where the once-lost maize was rediscovered. (Fred Powledge) |
Close to the highest point of a handsome mountain range in western Mexico, there is a rare plant, Zea diploperennis. The plant, which grows tall and skinny and looks almost like an ornamental grass, is a wild relative of what is known in the United States as corn and in much of the rest of the world as maize. After wheat and rice, maize is the planet’s third most important grain crop.
Until the late nineteen-seventies, scientists assumed that Zea diploperennis was extinct. They knew it had existed, because there were samples of it in biological collections, like the parched bones of dinosaurs in museums of natural history.
Hugh Iltis, a biologist who directed one of those collections, the University of Wisconsin Herbarium in Madison, had a habit of sending out Christmas cards with hand-drawn pictures of plants now believed to be extinct in the wild.
One of his cards made it to Mexico, where Iltis had done much of his plant collecting. It went to the University of Guadalajara’s biology department, to Maestra (Professor) Maria Luz Puga. Like scientists everywhere, Maestra Puga is reluctant to think of a species as being really extinct. Maybe there’s a mountaintop, or a valley, or a little patch of land behind some trees, where members of the species are still hanging on. She told her students in 1977 that any of them finding the plant in the wild would receive an “A” on the course, regardless of performance on the final exam.
A student’s dream.
Such an offer is a student’s dream, of course, and could hardly be ignored.
Before long, one of the scholars, Rafael Guzman, returned with a plant
that looked like the one in the drawing. A classmate, who was from
the Indian
community
of Cuzalapa in the Manantlán range, saw the sample. The same
plant existed where he lived, he said.
Rafael Guzman went to the Manantlán and hiked for two days before he found the plant, which he believed was Zea perennis, the one depicted on Hugh Iltis’s Christmas card. This is a perennial form of teosinte, which is an annual wild grass that science believes is the closest relative of maize. (Perennials bloom from year to year, while annuals spring from seed, mature, and produce new seed all within one year.) Guzman returned to Guadalajara with his samples, grew them out in the university’s greenhouse, and sent seeds to Hugh Iltis and others.
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| Eduardo Santana Castellon, who with fellow scientist Enrique Jardel Pelaez oversees the research station atop the mountain. Here he's examining the long-"lost" maize. (Fred Powledge) |
Plant scientists are constantly exchanging seeds with each other, to aid in identification, to see how a species adapts to other environments, and to generally spread knowledge.
Scientists in general do the same thing, though not necessarily with seeds. They present their ideas, discoveries, findings, and other data to their colleagues for verification and testing. Science is a collaborative undertaking. Rarely is a discovery or a new “law” of science the work of just one person. Usually, scientific discovery advances little by little, with many people contributing.
Iltis regarded the seeds with curiosity, but he did not think any sort of a stunning “breakthrough” had been achieved. Although it is believed to be maize’s relative, annual teosinte’s chromosome structure does not allow it to breed with maize. Scientists, including Iltis, had long wondered if there were a perennial teosinte somewhere that was capable of interbreeding. Iltis’s colleagues examined the genetic structure of the seeds. Sure enough, the plant was capable of crossbreeding. It was awarded the name, Zea diploperennis, and researchers began to study its characteristics.
Pleasant surprises.
The most noticeable of those qualities was the fact that it was a perennial.
Currently, farmers who grow annual maize must plant each crop from new
seed. A maize that could generate its own seed from year to year would
be a major discovery and work-saver. There was another pleasant surprise:
The newly rediscovered plant had resistance to several viral diseases.
If such resistance could be bred into commercial varieties of maize,
yield would increase, farmers could save on chemical costs, and the breeders
would make bundles of money.
Because research that is supported by universities and other public sources is based on the idea of the open exchange of plant material, or germplasm, experimenters all over the world asked for and got samples of the seed, free of charge. There was speculation that the commercial seed industry, which is happy to take free seeds from others but which likes to keep its own experimentation secret, would seek to incorporate some of Zea diploperennis’s qualities in hybrids for sale to farmers.
Hybrids. These
are crosses between two organisms, animal or plant, that are genetically
unalike.Obviously, there isn't a hybrid creature produced by a
cross between a turkey and a tomato. But such crosses can be made,
and frequently are, with closely related organisms. A horse and
a donkey can produce a mule; many of our favorite foods, including
corn, are hybrids. |
Zea diploperennis grows today, happy as a weed, in several patches in a saddle of the Sierra de Manantlán, near the 2,960-meter height of land. It rises close to two meters tall, its slender cobs hardly resembling the modern idea of “corn.” It is surrounded and crowded by other wild plants in a large plot of land that once was logged extensively, then used for cattle grazing, but that now is set aside for biological investigation. The Sierra de Manantlán Biosphere Reserve, as it is known, is one of the world's 324 such reserves, recognized by the United Nations as places of special significance in the effort to protect biological diversity while allowing human development. In the UN’s words, the idea is “improving human involvement with nature, in ways that satisfy human needs and support the long-term health of the natural system.”
It is almost certain that the reserve would not exist if Zea diploperennis had not been discovered. The environment of that part of Mexico, in the states of Jalisco and Colima, between the city of Guadalajara and the Pacific coast, has a long history of exploitation by ranchers, miners, and foresters. But once the rare plant was found and publicized and its local habitat protected, politicians got interested and scientists from the University of Guadalajara and elsewhere started looking more closely at the mountain range.
The more they looked, the more they found that was worth saving. They discovered more than 1,500 species of plants, 295 species of birds, 45 species of reptiles, 20 species of amphibians, 16 species of fishes, and 76 species of mammals (including all six of Mexico's wild cats.
| Worth saving. What would happen if a plot of land near you were suddenly designated a reserve? What do you think researchers would find there? There's undiscovered biodiversity all around us, even in our own backyards,waiting to be discovered. |
They also found indigenous communities of Indians who still practice agriculture in the old-fashioned ways. They found that, although only 5,000 to 7,000 people live within the boundaries of the reserve, some 400,000 people in the lowlands below depend on the quality and quantity of the water that comes down the mountain.
They found all this because of Hugh Iltis’s homemade Christmas card, Maestra Maria Luz Puga’s challenge to her students, Rafael Guzman’s acceptance of the challenge, his classmate's recollection, and the hard work that went into identifying Zea diploperennis. This is what plant exploration and collecting can accomplish.
To investigate the meaning of Zea diploperennis’s rediscovery, and the symbolic position it occupies in agricultural biodiversity, click here.