Saturday, January 11, 2003 (SF Chronicle)

Acorns, anyone?
Native plants mostly missing from American diets

Deborah K. Rich, Special to The Chronicle

Those opposed to nonnative plants best curb their appetite. The breadbasket of the world, as well as our home gardens, would be nearly empty without them.

Rows of corn and soybeans reach across the United States, and we claim the world capitals of lettuce, artichokes, broccoli and garlic. But, despite its productivity, the United States has contributed only one major crop, the sunflower, along with a handful of nuts and berries, to world agriculture.

Central America gave us our corn, China our soybeans, and Iran and Turkistan our lettuce. The Mediterranean provided our artichokes and broccoli, and Central Asia our garlic. Twelve crops -- wheat, corn, rice, barley, sorghum, soybeans, potatoes, manioc, sweet potatoes, sugarcane, sugar beets and bananas -- yield approximately 80 percent of the world's annual tonnage; none of those 12 originated in the United States.

Let's say we decide to plant a garden next spring dedicated to plants domesticated from wild species indigenous to the United States (as defined by its current boundaries). Forget the tomatoes and green beans, we'll be planting maygrass, sumpweed, little barley, knotweed and goosefoot.

Eastern American Indians domesticated these seed plants, in addition to the sunflower, between 2500 and 200 B.C.

Assuming we want to make a dent in the family food needs, we'll need to sow several acres of each of these cereals. Their small seeds yield a volume only one-tenth that of wheat or barley. And we'll have to be careful with the sumpweed; it is highly nutritious, being 32 percent protein and 45 percent oil, but it causes sneezing and irritates the skin when handled.

To supplement our cereals, we'll have one root vegetable, the Jerusalem artichoke (the starchy tuber of a species of sunflower), as well as acorn and summer squash derived from an indigenous Cucurbita pepo, and the strawberry. Plus, we can establish blueberry bushes and pecan trees (the latter taking 20 years to reach full productivity), and those in the Northern states can raise cranberries and wild rice.

This winter we should clean Grandpa's rifle and study for a hunting license.

No domesticated indigenous legume varieties exist to provide the protein that the cereals, other than sumpweed, lack. Neither do we have any domesticated indigenous fiber plants. Luckily, we're only trying to feed ourselves with this native garden and can disregard attire.

Plant domestication involves genetically changing a plant, purposefully or by chance, to make it more suitable for regular cultivation and use. No single reason fully explains the United States' historical failure to domesticate more indigenous plants. The population trends of the Indians, the particular mix of flora and fauna that evolved in the United States' territory, the debut of the three sisters of Mexican agriculture and the rapid influx of European colonialists all influenced our national crop development.

"One of the reasons why the Native Americans didn't domesticate more crops was the availability of so much food," says Ted Hymowitz. Hymowitz, a professor of plant genetics at the University of Illinois at Champaign-Urbana, studies the influence of plants on people and vice versa. "They had fish, crustaceans, clams, birds of all kinds, bison running in the plains. Plus there weren't that many people around."

Phil Simon, research leader of the ARS Vegetable Crops Research Unit in Madison, Wis., agrees that lack of motivation, due to alternative food sources, largely explains why the Indians didn't domesticate more crops. "Part of the development of civilizations is a function of need. Native Americans were able to hunt and gather and exist quite adequately," suggests Simon.

In his book "Guns, Germs, and Steel" (W.W. Norton, 1997), author Jared Diamond proposes that the primary reason behind our lack of major indigenous crops is the plants themselves. Diamond argues that wild plants that lend themselves to domestication are simply not as prevalent here as in the Fertile Crescent, China, Mexico and Central and South America -- areas that originated most of the world's major crops. "Indigenous crops from different parts of the globe were not equally productive," he writes.

Ironically, though we lack their wild ancestors, most of the world's most important crops grow well here. Hymowitz and Simon speculate that only the dynamics of plant evolution and climate change can explain why the crops' wild ancestors didn't evolve within the United States borders, despite the ease with which these crops have transferred to our shores.

The absence of wild ancestors of livestock suitable for domestication in the Americas compounded our relative disadvantage in wild plant species, suggests Diamond. Without animals to plow fields for broadcast planting, cultivating cereals, especially low-yielding ones, would have been an unattractive and extremely labor-intensive proposition.

Simon believes that the lack of domesticated animals further diminished the Indians' motivation to farm. "Maintaining animals is difficult and soon requires growing crops." The Indians didn't have the added incentive of hungry livestock encouraging them to farm.

Even the oak, whose acorns provided Indian a generous and easily gathered harvest, escaped domestication. Acorns do contain bitter tannins, but the Indians learned to remove the tannins by leaching the acorn meal. More important, some mutant oak trees produce acorns low in tannins. Yet neither Indians nor European colonists did not domesticate this obvious food crop by selecting for non-bitterness using the occasional mutant oak as a seed source.

Diamond blames the fact that multiple genes control bitterness in oaks. The wild ancestor of the almond, found in the Mediterranean, was not only bitter but also highly toxic. Like the oak, occasional mutant wild trees yield almonds without the toxic and bitter compounds. "Sweet" almonds became the source of the domesticated almond tree. The difference between the mutant almond and acorn is that a single dominant gene controls bitterness in almond trees, whereas multiple genes control bitterness in oaks.

"If ancient farmers planted almonds or acorns from the occasional nonbitter mutant tree, the laws of genetics dictate that half of the nuts from the resulting tree growing up would also be nonbitter in the case of almonds, but almost all would still be bitter in the case of oaks," writes Diamond.

With relatively few domestic successes of its own, early U.S. agriculture lay ripe for takeover. Corn and beans, two of Mexico's three sisters of agriculture, made the first conquests of our Indian crops between A.D. 200 and 1100. The Indians of both the United States and Mexico independently domesticated squash, the third member of Mexico's nutritionally complete trilogy. By the time the Europeans arrived in the late 1400s, corn and beans had replaced many U.S. Indian domesticates, and corn, beans and squash dominated early U.S. agriculture.

The European colonists completed the near-total conquest of Indian crops. By ship and mule train they brought in seeds of their own agricultural contenders, largely products of the Fertile Crescent and Mesoamerica, and by war and pestilence they almost wiped out the Indians.

"I think that if the American Indians had more time, they would have domesticated more plants," said Hymowitz. "We're only talking 12,000 to 15,000 years, since the last glaciers receded. The Fertile Crescent had more time." Archaeological evidence places Homo sapiens in the Fertile Crescent region as early as 500,000 B.C.

But just how many more plants the Indians might have domesticated remains a question. Even modern plant breeders have domesticated only a few additional indigenous species, including the pecan, the blueberry, the cranberry and wild rice, and improved a handful of Eurasian and South American fruit crops by combining them with our wild varieties of apples, grapes, plums, raspberries and blackberries.

John Kallas, founder of Wild Food Adventures, doesn't believe that modern breeding's few successes lend credence to the argument that the United States lacks readily domesticatable species. "For a lot of wild foods, there is no inherent reason why they can't be domesticated and used," says Kallas.

He believes that the true hurdles to modern use are our agricultural and marketing systems. "Modern large-farm agriculture doesn't allow for lots of diversity," says Kallas, "and there is a lack of common knowledge about indigenous foods. They have to be introduced in a way that people can accept."

Breeding does continue on selected native food plants. The Land Institute in Salina, Kan., hopes to develop perennial wheat and rye through hybridization with related indigenous perennial species. Perennial grains have the potential to reduce our dependency on agricultural chemicals.

"Current annual monoculture systems leak nutrients into the ground and surface waters," said Lee R. DeHaan, a plant breeder at the Land Institute. "They result in poisoning of lakes, streams and groundwater with pesticides. Mixtures of perennial plants could function like a native prairie, cycling nutrients, controlling pests and weeds, and eradicating erosion."

The Horticulture Research Program at Kentucky State University sponsors a breeding program directed toward developing the pawpaw (Asimina triloba (L.) Dunal) tree as a commercial fruit crop for the southeastern United States. The pawpaw, our largest native fruit, reportedly tastes like a combination of banana, mango and pineapple and can maintain good eating quality for as long as three weeks if properly refrigerated.

Whether modern breeding programs will ever fill our breadbasket with native grains remains to be seen. Until then, credit is due the nonnatives. Pass the rolls, please.

Copyright 2003 SF Chronicle