THE HISTORY AND NATURE OF FOOD PLANTS
The most remarkable fact concerning the food plants in use in the world today, and for that matter the industrial plants as well, is their great antiquity. Most of them were domesticated from wild ancestors long before the beginning of the historical period, and all available records indicate that they were as familiar to the peoples of the ancient world as they are to us. Comparatively few new plants have been developed during the last 2000 years, although the older ones have been greatly altered and improved in response to the increasing complexity of man's existence.
The history of our useful plants and their influence on civilization has always been of interest to botanists and ethnologists. Many investigations have been carried on in an attempt to determine their age and place of origin, as well as their cultural history.
The Work of De Candolle. The classic work dealing with this phase of botany is De Candolle "L'origine des plantes cultiveés," which appeared in 1883. So careful and painstaking was his work that few of his conclusions regarding geographic distribution have had to be altered in the light of more recent studies. His dates, however, are of little or no value. De Candolle (Fig. 144) based his conclusions on a great variety of evidence: the works of Theophrastus, Dioscorides, and other old historians; Chinese writings; archeological and ethnological data, such as the monuments of Egypt, the ruins of Pompeii, the remains of the Lake Dwellers of Europe, and the Inca ruins of South America; philological indications, involving the names of plants in Hebrew, Sanskrit, and other ancient languages; and botanical conclusions based on distribution, number of varieties, presence or absence of wild types, length of cultivation, and similar matters. He arranged the useful