It's early spring at Heritage Farm, six miles north of Decorah, IA, near the Minnesota border. Although patches of snow cover the ground, the 35 organic gardens here will soon throw off Nature's icy grip. Within weeks, cabbage, leeks and other frost-tolerant greens will make their appearance. By May, when the trees bud and the first tourists arrive, the lettuce and peas will be up. In the white pine woods that cover this 890-acre property, the trillium, hypatica and Dutchman's Britches will bloom. By midsummer, some 2,000 varieties of vegetables will be growing. There will be 200 varieties of peas, 300 peppers, 500 tomatoes, 500 beans--all endlessly rotated, decade after decade.

In this way, 24,000 rare vegetable varieties are permanently maintained for generations to come in this unique nursery/museum. These are not just any vegetables, either: Heritage Farm is the only place you're likely to come across Fish Peppers, Dinosaur Gourds, Rat-Tailed Radishes or Green Zebra Tomatoes. Or flowers such as Outhouse Hollyhocks or the red-flowered annual, Kiss-Me-Over-the-Garden-Gate.

Every, plant at Heritage Farm--fruit, vegetable, herb or flower--is an heirloom. Each has a story to tell. "Some of these seeds came from Europe in the hatbands, coat pockets and skirt hems of immigrants eager to bring something of their old homes with them when they came through Ellis Island," says Diane Ott Whealy, who started the farm 30 years ago with Kent Whealy, to whom she was then married. "The descendants of these immigrants give the seeds to us so these precious resources can be preserved, If you don't make an effort to save these plants, as we do at Heritage Farm, they will be lost."

IN THE ORCHARD

Down past the handsome red barn built by Amish carpenters is Heritage Farm's Historic Orchard. Here, 70 varieties of apples will be picked this fall. That might sound like a lot, but it's only a fraction of the 700 varieties being preserved by the Seed Savers Exchange, the nonprofit organization that maintains Heritage Farm. That, too, may sound like a lot, but in 1900, there were about 8,000 varieties in this country. The vast majority are now gone, and Seed Savers is determined to safeguard those that survive.

"Unlike a piece of old family furniture that can be refinished, dusted and stored in an attic, seeds need to be grown," Whealy says. "The genes they carry can be stored in only one way: in a living system. That means in an orchard or garden on a farm like ours."

Keeping these genes alive and well is important for the health of all plants and for the preservation of the food supply. Almost all crops today are grown in what are called monocultures, meaning only one variety of plant--fruit, vegetable or grain--is grown over hundreds and sometimes thousands of acres. Every acre is covered with plants that have the same genetic makeup, a condition unknown in nature. They share the same vulnerabilities to weather, pests and disease.

"Monocultures are inherently dangerous," says John Navazio, a plant breeder in Townsend, WA, who earned his PhD in plant breeding and genetics from the University of Wisconsin. "When you have that much genetic homogeneity in one place, it's an invitation for insects or disease to wipe out the entire crop."

In 1997, for example, a new plant disease called Stemphylium leaf spot appeared in Salinas County, CA, devastating spinach production. "The Stemphylium outbreak is a perfect example of what can happen when our entire production of a given crop is based on one variety of the plant," Navazio says. "The narrower a crop's genetic base--and our spinach is based on a small group of closely related varieties--the more vulnerable it becomes."

RAISING AWARENESS

Open to the public and visited by 5,000 people every year, Heritage Farm has done more than help backyard gardeners appreciate the diversity of plant species and the need to protect them. It has "also contributed immensely to the growth of organic farming by making seeds available to the movement.

"When I first got involved in plant breeding in the '70s, we all just assumed that the seeds we liked would be available next year," Navazio says. "Over the past 25 years, Heritage Farm and Seed Savers have helped all of us in organic farming understand that the plants we love could someday be gone. This was a huge revelation to me. Now, thanks to the Whealys, I know that you have to protect these varieties."

Protecting these plants and the genes they carry is important not just to gardeners and farmers, however. Our food supply depends on our ability to develop insect-and disease-resistant crops, which is where genetic diversity comes in. "To keep our food crops from being devastated by these threats, plant breeders need to be able to draw on the genetic material in these varieties," says Mark Widrlechner, an assistant professor at the North Central Regional Plant Introduction Station at Iowa State University at Ames.

"Seed Savers Exchange serves as an important reservoir of interesting genetics useful to modern agriculture. Only by drawing on the plants that seed banks preserve can new varieties be developed."

LESSONS LEARNED

A former dairy, farmer, Diane Whealy herself did not begin to understand how vulnerable or valuable these plants are until 1975. That's when her terminally ill grandfather gave her the seeds of two plants that his parents had brought with them from Bavaria in the 1870s. The plants, since named the German Pink Tomato and Grandpa Ott's Morning Glory, were the first of thousands to be safeguarded by the Whealys.

"It was that gift from my grandfather that sparked our interest in heirloom plants," she says. "Pretty soon, people were giving us seeds from all over. We were living in a rented farmhouse at the time, and it was a struggle. At first, the seeds were stored in other peoples' freezers all over the country. In time, we had to rent farmland just to grow them."

Three decades later, the nonprofit organization that the Whealys began employs a full-time staff of 15, which doubles during the busy summer months. The nonprofit operates a Seed Savers Garden Store three hours east in Madison, WI, and publishes an annual catalog, which is sent to 100,000 farmers and gardeners. For $35 a year, members of the Seed Savers organization also receive the Seed Savers Yearbook, which offers the seeds of nearly twice as many vegetables as its mail order mad online catalogs do.

WHAT'S NEXT

If you visit Heritage Farm this summer, a guided tour of 56 acres that are now open to the public will take about an hour. In coming years, there will be much more to see. "We are in the process of buying 800 more acres that adjoin this property, so we will be able to protect all of this land," Diane Whealy says.

Immediate plans are to develop still more gardens, which will enable the land now under cultivation to rest. Isolated in the woods, these new gardens will also be linked by walking trails. Some of the streams will be fenced off and a native strain of trout will be re-introduced.

Of course, some things about the farm will remain unchanged. That, after all, is the point. Summer after summer, for example, the red barn will be completely covered with the dark purple blossoms of a vine that visitors don't recognize and often ask about. "Those," Diane Whealy says with pride, "are Grandpa Ott's Morning Glories."

ABOUT THOSE cows ...

The 80 white cattle that graze at Heritage Farm represent about 10 percent of the only survivors of the Ancient White Park breed. Most cattle breeds are only 200-300 years old. The Ancient White Park, ,which may go back to the Roman Empire, were first described in 'The Cattle Raid of Cooley, an Irish saga dating to 200 AD. Bred for centuries in England, Scotland and Wales, the cattle were shipped to the Bronx Zoo just before World War II to safeguard them in case of Nazi invasion. After the war, the herd was moved to the vast King Ranch in Texas where the cattle lived until their purchase in 1981 by an Iowa family. At the end of the 80s, the Seed Savers Exchange bought about half the herd, which is being successfully rescued from extinction through breeding programs.