The original publication of Our Vegetable Travelers appeared in the August, 1949 issue, Volume 96(2) of National Geographic Magazine and is copyrighted by National Geographic Magazine. Reprinted as a special feature in the PLANTanswers section of Aggie Horticulture by permission of the National Geographic Society. February, 2000.
Our Vegetable Travelers
By VICTOR R. BOSWELL
Principal Horticulturist, United States Department of Agriculture
"So far, I’ve grown only American vegetables," he said. "Next year I want to go in for foreign things. Do you know a good place where I can get seeds of foreign plants?"
Glancing over his jumble of plants and making a tough mental calculation, I said: "Those tomatoes, snap beans, peppers, lima beans, and potatoes are the only truly American vegetables you have. All the others are foreign-onions, radishes, lettuce, spinach, beets, chard, cabbage, broccoli, collards, carrots, parsley, turnips, peas, asparagus, soybeans, mustard, eggplant, and the rest of them.
"The foreign plants in your garden outnumber the native ones by about five to one."
"What do you mean, ‘foreign’?" he asked. I bought the seed for all these right here in town, and I’ve always eaten most of these things. They’re common."
"Yes, they’re common to us," I agreed, "but their ancestors were foreigners to America, the same as your ancestors and mine."
Thus my friend became interested in the origins as well as the growing habits of plants, and now he includes plant history as part of his hobby.
When Dr. Grosvenor, Editor of the National Geographic Magazine, asked me if I would help in presenting this story, I welcomed the chance to answer a few of the most often-asked questions about the origin, nature, behavior, and travels of the vegetables now most commonly grown in the United States.
More Vegetables Eaten than Ever Before
Americans have become great vegetable eaters. We eat more "store vegetables" than ever, and the growing of vegetables in home and community gardens has become more extensive than at any time in our history except during periods of national emergency.
We like our vegetables fresh from the garden; we like many of them raw; and we want them the year round. Our use of fresh, canned, and frozen vegetables-except potatoes and sweet potatoes-has increased, per person, steadily for 25 years and more, while our use of potatoes and grains has steadily decreased.
"Truck crops" we call our vegetables. The expression has no connection with the fact that they are commonly hauled to market in motor trucks (formerly in wagons or carts), but it reveals an interesting bit of history about the early vegetable business.
One old meaning of the word "truck," derived from the French word troquer, is "to barter or exchange." In the United States the word developed a special meaning as a synonym for vegetables in general because of the practice of bartering or dealing in small lots of them in the market. Vegetable growing in America today has come far from the days of small items that were commonly bartered; it has become big business. The truck gardeners who worked small areas near towns and cities are being displaced by truck farmers who grow huge fields of vegetables farther and farther away from the centers where they will be used.
What is a vegetable, exactly? What is the difference between a fruit and a vegetable? Is a tomato a fruit or is it a vegetable?
These questions are asked many times in our work, not only from curiosity but often for business reasons.
We can give some very confusing answers because there are no definitions that will hold without qualifications or exceptions.
In 1893 the Supreme Court of the United States rendered a decision to the effect that the tomato is a vegetable! An importer had argued that tomatoes were fruit and hence, at that time, not subject to duty. The court held the tomato to be a vegetable because it was usually served at dinner in, with, or after the soup, or with fish or meats that constitute the main part of the meal. In the last few years in the United States a much larger part of our tomato crop has been canned in the form of juice than as whole tomatoes. Apparently we now drink a major proportion of our tomatoes before the main part of any meal, as we drink a large share of our crops of oranges and grapefruit. Many tomatoes today are also made into preserves with sugar, or eaten raw, like fruits. Still, the tomato is "legally" a vegetable.
Of course all botanists know that by botanical definition the tomato is a fruit. They also know that the snap or green bean, the pod of peas, the garden pepper, the okra pod to name a few-also are fruits, botanically. Still, no one doubts that they are vegetables.
Muskmelons and watermelons, too, botanically are fruits; they meet the Supreme Court’s implied definition of fruits, and still they are grown by truck farmers, and agricultural students in America study melons in courses on vegetable culture.
The cucumber and the muskmelon are rather closely related; they belong to the same genus, Cucumis. They are similar in habits of growth and in structure; both are grown by truck farmers by similar methods, and both move through the same channels of trade. The fruits of both are eaten raw.
Yet we say that cucumbers are vegetables and that muskmelons definitely are fruits! Thus it is evident that there is no clearcut distinction be plants called vegetables and those called fruits. Specific plants are arbitrarily placed in one of these two categories as a matter of custom. Here we shall be consistent with the inconsistencies of our American language and customs, and deal with melons along with other truck crops. Melons are truck crops, yet they are fruits.
Generally speaking, however, we classify as vegetables those annual plants of which the immature succulent roots, bulbs, stems, blossoms, leaves, seeds, or fruits are eaten; also those perennial nonwoody plants of which the roots, stems, leaf stalks, or leaves are eaten.
Scientific Detectives Trace Plants’ Origin
The ways archeologists, historians, geographers, botanists, and others have tried for centuries to find out where our vegetables came from makes an interesting story in itself. Shrewd scientific detectives are still at the job, trying to fill the gaps in our knowledge and to define with ever-increasing exactness where this or that species originated.1
Nowadays these investigators are driven on by a practical purpose. If we know the origin of a plant, we know where to look for different forms having characteristics that might be valuable in present-day crop breeding.
Plant-hunting expeditions are sent to the supposed region of origin of a species in the hope of finding cultivated or wild forms, or even closely related species, that may help improve our crops. The early students of plant origins had only folk tales, sketchy records of travelers, and old writings to help them. Such sources gave a few valuable clues, but most vegetables came into use as food long before there were any known written records.
As prehistoric peoples moved about, even from one continent to another over land bridges or short stretches of water, they sometimes carried with them seeds of plants they had learned to use for food. By the time the oldest known records were written or carved, many plants were known over relatively vast stretches of the earth, particularly in Eurasia and parts of Africa.
This wide scattering of vegetable plants at the very dawn of history complicates the task of determining the exact region where they were first used as food.
Because some vegetable has been known from the beginnings of history in widely separated lands, the people in each of those lands believed the plant to have been there "always," to have originated there. Modern research has shown many of those beliefs to be wrong. Exploration and archeological search have uncovered many new clues.
One of the best evidences of origin of a cultivated plant is finding the place where its ancestral form is still growing in the wild. But finding wild forms as weeds in a particular place, or finding cultivated plants that have escaped into the wild, proves nothing about their origin. Wild carrot grows over much of the United States, but it is not native here.
Botanists now rather generally accept the theory that the region having the greatest diversity of forms of a given kind of plant is the probable center of origin of that plant.
Of many important crops, however, no one has ever been able to find a wild form anywhere in the world. Maize (Americans call it "corn") is an important example. Either its wild parent has vanished from the earth or it has become isolated in some areas of the South American lowlands where literate man has never penetrated.
Number of Tribal Names Gives Clue
Plant names help the plant historian. Finding numerous names for a single plant among widely scattered tribes in a primitive country indicates antiquity of the plant in that area. If there is no such multiplicity of names in languages of other lands, the plant is suspected of being native to the land where it has many.
When the white man first came, he found our present common bean (Phaseolus vulgaris) widely scattered in North, Central, and South America, with each tribe that grew it having its own name for the bean.
For example, it was called sahe or sahu by the Indians on the St. Lawrence River; ogaressa by the Hurons; tuppuhguam-ash by the northern Algonquins; malachxil by the Delawares; okindgier by Indians on the Roanoke River; ayacotle and etl by the Aztecs.
Each tribe had grown this bean "always," meaning as far back as their folk tales could tell them. Many kinds of beans were known in the Old World, but for this particular one there were no descriptions or names in Old World languages until after 1492. During the 450-odd years since Columbus’s discovery of America, our American type of bean has become spread all over the globe and has long been grown in many lands-China, for example.
The Chinese have grown such a diversity of forms of this species that China has been designated by one authority as a "secondary center of origin or distribution." Nevertheless, other available evidence points to a strictly American origin.
Other American vegetable species, too, were so quickly scattered over the earth after about 1500 and were grown so extensively that for many years their American origin was overlooked. Some-peppers, for instance-were believed to be of 0riental origin.
Former confusion over the bean, the garden pepper, and the sweet potato show how easy it has been to lose sight of the hemisphere of origin of certain plants even within recent historical times. Imagine the difficulty of tracing back the history of Old World plants to the country of their origin after they had been shuttled about over Eurasia and parts of Africa for thousands of years!
Findings of Archeologists Help
The archeologists, too, have made their contributions to plant history. Ancient carvings, records in stone, ornaments, and decorated utensils describing or depicting food plants have been found in tombs and remains of dwellings in many parts of the world.
Even seeds of very ancient varieties of vegetables have been found. We should say "remnants" of seeds, because the life had long since gone out of them when found. Fragile shapes of matter that would crumble with little more than a touch were often all that remained. The seeds could be identified, but, contrary to recurring tales, they would not grow.
Many sincere persons have been victims of one hoax or another involving seeds alleged to have been found in an Egyptian tomb or some other very ancient repository. In the best of faith, enthusiastic recipients of such seeds have planted them, and then, amazed by their growth, shouted their discovery to the world.
On one occasion seeds of a grain were found in the wrappings of an Egyptian mummy. They were planted and they grew. This appeared to be a most unusual case until it was discovered that the seeds came from incompletely threshed straw of a recent crop used in packing the mummy for shipment.
Microscope Helps Show Corn’s Ancestry
In recent years the microscope has been used successfully in technical studies in heredity in trying to ferret out obscure characteristics of different species that may be native to different, regions.
It is now possible with some plants to confirm their supposed origin with reasonable certainty by the shapes of the chromosomes, those minute structures within the cell which are the seat of the hereditary mechanism of the plant.
For example, although maize almost certainly originated in South America, our North American types have chromosomes more like those of the maize of Central America than that of Peru.
Thus it appears that our North American kinds of corn are directly descended from Central American forms, which in turn are the result of prehistoric hybridization between South American maize and a closely related wild species of Central America having the same ancestor as maize.
This remarkable piece of genealogical detective work required many years of investigation by many men and a 315 page monograph to bring the whole story together.
Much human progress had been made even before history began. Some civilizations, including sizable cities, rose, flourished, and disappeared with only circumstantial evidence today as to what happened to them.
How were the people of those cities fed? What did they eat? Where did their food plants come from? Were those plants wild or cultivated? There must have been an agriculture, since cities cannot feed themselves on wild plants and game alone.
Agriculture, the purposeful rearing of animals and the cultivation of plants, began to develop in the last part of the Stone Age, along with man’s learning how to make pottery and how to sharpen tools by grinding instead of chipping.
Agriculture did not come about all over the inhabited parts of the earth at the same time. In some parts of the world there are primitive cultures, even today, that have developed little if any beyond the Stone Age.2
Man’s first efforts at agriculture doubtless were directed to those plants which produced a good yield of palatable seeds that could be stored easily for food, or which produced large, fleshy, underground parts that would persist in the soil from one season to the next and could be dug up when wanted. Many highly perishable leafy vegetables and fleshy fruit vegetables came into cultivation later.
Eastern Mediterranean Contributed Most
Of the eight or ten main centers of origin of vegetables and other economic plants, the lands about the eastern end of the Mediterranean Sea and well inland are credited with the largest number of vegetables now grown in America. Among them are asparagus, beets, broccoli, cabbage, cauliflower, celery, endive, kale, lettuce, parsley, parsnips, and rhubarb.
This area, from Asia Minor to Egypt, includes the world’s most heavily traveled corridor of prehistoric migrations and also a wide range of climatic and soil conditions.
We cannot be sure that all plants apparently originating there actually did so. Many kinds may have been carried there by migrants from farther east or north.
Several vegetables of supposedly primary origin in the Mediterranean, such as cabbage, lettuce, beets, and parsley, show other centers of origin or distribution in the Near East, and vice versa. Likewise, many kinds of vegetables show centers in both the Middle East and the Near East, such as peas, Indian mustard, carrot, onion, and muskmelon; or in both the Middle East and India.
The Mediterranean center, the Near East center, including the trans-Caucasus area and Mesopotamia; and the Middle East center, including Afghanistan and adjacent areas, tend to make a large geographic unit from west of the Himalayas to the Mediterranean.
Although there were barriers to movement of prehistoric peoples within this area, those barriers were less formidable than those to the east and south. The migrating peoples certainly carried seeds with them.
Early inhabitants of Mesopotamia, the non-Semitic Sumerians, had developed an advanced civilization, with important cities and trade with other lands, even before 4000 B.C., when most of the world was far less advanced.
Where they came from we don’t know, but they doubtless brought seeds of crop plants. By about 2750 B.C. they had touched the Mediterranean.
Then Semitic peoples from the west invaded Mesopotamia, and later the Aryans from the east shoved into it, each doubtless carrying seeds of their favorite food crops.
Still later the Aramaeans, a people from the northwest, invaded the country.
In 539 B. c. the Persians took over.
Thus there was a gradual crossing and recrossing, infiltration and transportation of peoples from west, north, and east that can be traced vaguely for thousands of years.
Peoples, animals, and doubtless plants, as well as ideas, religions, and cultures, became distributed. So it is not surprising that many species have more than one center of development and that it is not possible to say finally which center developed first.
About the time the New Stone Age man of the Near East was pushing to the eastern Mediterranean, in the third millennium B.C., he was also moving through Asia Minor, across the Dardanelles, along the coast of the Black Sea, and into the Danube Basin of Europe. His arrival appears to have coincided with the first agriculture in eastern Europe.
The plants first cultivated in Europe are Asiatic in origin, and archeological finds indicate that their culture in Europe is less ancient than in the Near East and middle Asia.
Migrations into the Aegean and middle Mediterranean, both by water and by land, further distributed a large number of Asiatic plants into southern Europe.
Early peoples of the Near East either dominated or influenced the whole of Eurasia in prehistoric times, and indirectly, therefore, the rest of the world. Recent botanical evidence of western Asiatic origin of so many of our present vegetables is accordingly in no conflict with the archeological evidence of the rise of civilizations all over the globe.
Plant Immigrants from the Orient
The Far East has given the world more cultivated plants of all kinds than has any other large area. Among these are many vegetables now grown in America, including various mustards, radishes, Chinese cabbage, soybeans, cucumbers, eggplant, and cowpeas.
The Chinese center of plant origins, chiefly in central and western China, was the most prolific, and that of middle and eastern India next. While Malaya and Indochina have contributed many economic plants, few are classed as vegetables and none is important in America.
Despite the evidence of contact between China and western Asia in prehistoric times, there is less evidence of diffusion of plants back and forth between China and middle Asia than between the Mediterranean and middle Asia. Geographic barriers have tended to keep isolated these cultural and biological areas of China, seat of one of the oldest continuous cultures now in existence.
Abundant evidence of late Stone Age man has been found in China. He lived in rude villages, hunted, fished, farmed, had domestic animals, and presumably used several of the vegetables cultivated today.
India has contributed many of the world’s cultivated plants, but of these only three are important as vegetables in America: cowpeas (black-eyed peas), eggplant, and cucumbers.
In the hazy prehistory of India there is far less evidence of numerous large migrations of peoples and cultures-and plants-than in the areas to the west. This may be one reason why the numerous vegetables and related crops originating in India are not more important outside India today. Africa has contributed only two vegetables common to us, okra and watermelons, and Australia not a single one.
New World Enriched Old’s Larder
Perhaps the least ancient, but not the least important, agricultural civilizations were developed in the New World, chiefly in mountain valleys of Central America and in the Andean and neighboring areas of South America.
These civilizations had developed so recently and had been so completely isolated from Eurasian and African cultures that they had made no evident contributions to Old World agriculture, arts, customs, thought, or racial composition before Columbus.
Very soon, however, after the voyages of Columbus and the Spanish explorers, the world was enriched by many important new food plants from the Americas, including maize, potatoes, sweet potatoes, tomatoes, peppers, squash, common beans, and lima beans.
By the time of the early American explorations, Eurasian civilizations were highly developed, with means of travel and methods of disseminating ideas and goods. Thus the finding of valuable New World food plants was followed by their world-wide exploitation at an almost explosive speed. Within a couple of hundred years many American plants, previously unknown elsewhere, were becoming important foods on every continent.
Archeological and racial evidences suggest that man first reached the Americas far back in the Stone Age by slow migration from eastern Asia. He came either by way of a land bridge then connecting Asia and North America where the Bering Strait now narrowly separates Alaska from Soviet Russia, or by rafts or skin boats across that strait.3
At that stage of his development man was no farmer. He subsisted by hunting, fishing, and harvesting whatever food the wild plants might offer him. It is thus improbable that this early migration involved any transport of Asiatic species of plants to America.
After untold generations this thin stream of man had trickled along the length of North America, through Central America, the Isthmus of Panama, and ultimately the full length of South America. Groups stayed behind along the way, as in Central America, and ultimately evolved distinct tribal* characteristics and cultures. Others pushed on toward somewhat different destinies.
As these American Indians in different regions-even in the two different continents-became better adjusted to the environments into which they were going, they learned to take advantage of and even to depend upon the wonderfully productive native plants that they found in their respective parts of the Americas.
Two distinct civilization centers developed, and both became main centers of origin of our present important native crop plants. One was in Central America, the other on the slopes and plateaus of what is now southern Peru, Bolivia, and northern Chile.4
The Central American area was probably mainly dependent first upon beans, sweet potatoes, squash, and pumpkins, while the early Andean people grew maize, potatoes, and tomatoes. Before the white man reached the Americas, however, further diffusion of the people had rather thoroughly distributed most of the crops over those parts of all the Americas where they could be grown successfully.
"Taming" Wild Vegetables
The difference between our cultivated varieties and the wild forms from which they came is due only in part to the fact that the cultivated kinds are sown in rows, fertilized, weeded, and otherwise given favorable growing conditions.
If wild forms are planted and given the best of care, the plants might grow somewhat larger than in the wild or make somewhat larger yields, but they would still be "wild" plants. Merely continuing to plant all the seed from such plants year after year, and tending the plants carefully, would not make "cultivated" plants of them.
What, then, did prehistoric man do to improve wild plants? And how are our plant scientists any better at the job of improving plants than our prehistoric ancestors were?
The important distinction between "wild" and "cultivated" plants is that wild plants perpetuate themselves under conditions of chance pollination and natural selection only. Our cultivated plants are the result of innumerable generations of either purposeful or unwitting selections by man. Man adds nothing to the hereditary make-up of the world of plants, but does take advantage of the endless diversity that Nature provides.
Prehistoric man noticed that some plants were better for his use than others; so naturally those were the ones he chose, century after century. Since he planted seeds of plants or fruits that he had chosen to use, he more or less automatically practiced plant selection of a sort.
Geneticist Speeds Plant Improvement
Thousands of years of discarding what is undesirable to man and propagating what is desirable to him developed our cultivated plants. For man’s needs they are considered highly superior to their wild ancestors, but in getting certain qualities desired by man we have unwittingly sacrificed other qualities for example, the ability to survive under adverse conditions.
By choice of parent plants, controlling pollination, and wise selection and testing of the plant offspring through successive generations, the modern plant breeder may obtain, in a few years, especially desired combinations of existing hereditary factors that might not be found in the wild in hundreds or even thousands of years. But he must first find somewhere in the world the parent plants that already possess the hereditary factors needed.
The geneticist creates no new factors, but he does invaluable rearranging of existing factors. He is rapidly finding factors that no one has known about, and learns how they are inherited, so that plant improvement can be carried forward speedily.
The art and practice of plant improvement goes back to prehistoric times, but the science of how specific characters are inherited was born since the birth of many men now living. We could still make plant progress without the science of genetics, but it would be too slow and costly.
Plants Shown in Countries of Origin
In the 32 paintings that accompany this article, the backgrounds typify the general regions in which each of these vegetables originated. They illustrate those areas, or well-known features of them, as they appear in modern times. Most crops illustrated are far older than any signs of civilization that can be seen in those lands today.
The fruits, pods, and even the leafy edible parts of many of the vegetables are so hidden by luxuriant leaves that they cannot be seen without pulling the leaves aside. Roots and tubers are, of course, obscured by the soil.
The fruits of melons and vining squashes are so large and so far apart on the vines that the illustrations cannot show the details of the way they grow. Few vegetables can be shown in detail as they grow in the garden.
To show the principal features of some crops, Mrs. Bostelmann had to remove a part of their leaves; to take only a branch of this kind or a piece of vine of that kind; to harvest the fruits of others and put them in a pile, omitting details of their natural habits; to harvest others from the soil; or to show some of the less common varieties that have growth habits convenient to our purpose.
Some of the vegetables, or parts of them, are painted about half natural size, while others, because of their large size, had to be greatly reduced.
Different stages of development, such as the harvest stage of some of the leafy salad plants and the flowering or seed-bearing stages of the same plants, are sometimes shown on the same plate, although these different stages of development actually occur months apart. Only by such devices can the artist condense such a wealth of form and color into so little space and in such a beautiful manner, as she has done previously with flowers.5
1The work of numerous scientists has been drawn upon freely in preparing this article, especially: Origin of Cultivated Plants, by A. de Candolle; Sturtevant’s Notes on Edible Plants, edited by U. P. Hedrick; Botanical-Geographic Principles of Selection, by N. I. Vavilov; and The Origin of Indian Corn and Its Relatives, by P. C. Mangelsdorf and R. G. Reeves.
2 See "Earth’s Most Primitive People," by Charles P. Mountford, NATIONAL GEOGRAPHIC MAGAZINE, January, 1946.
3See "Exploring Frozen Fragments of American History," by Henry B. Collins, Jr., in the May, 1939, NATIONAL GEOGRAPHIC MAGAZINE.
4 See, in the NATIONAL GEOGRAPHIC MAGAZINE: "Further Explorations in the Land of the Incas," by Hiram Bingham, and "Staircase Farms of the Ancients," by 0. F. Cook, May, 1916.
5See "The World in Your Garden," by W. H. Camp, with 24 paintings by Else Bostelmann, National Geographic Magazine, July, 1947. The many articles on plants and plant hunting which have appeared in the National Geographic Magazine include the following by David Fairchild: "Hunting Useful Plants in the Caribbean," December, 1934; "Hunting for Plants in the Canary Islands," May, 1930; "New Plant Immigrants," October, 1911; and "Our Plant Immigrants," April, 1906; also "Peacetime Plant Hunting About Peiping," by P. H. and J. H. Dorsett, October, 1937; and "Hunting the Chaulmoogra Tree," by Joseph F. Rock, March, 1922.