DOMESTICATED PLANTS — BLAYDES 325 



the first people of the New World. Maize or corn, with perhaps more 

 than 8,000 varieties and the only important cereal which originated in 

 the Americas, should head the list; the potato in its many varieties, 

 now a staple food of many millions of people; the sweetpotato with- 

 out which no vegetable counter is complete the year round, also a great 

 source of commercial starch ; cassava, a staple food in the Tropics, and 

 a source of waxy carbohydrate used in the manufacture of tapioca; 

 arrowroot and canna yielding starch for fine pastries ; lima beans in 

 considerable variety ; kidney beans, from which snap beans, soup beans, 

 and field beans developed ; tomatoes, millions of tons being consumed 

 annually in the United States today ; hot and sweet peppers, widely 

 used as condiments and to camouflage left-over ground meats ; tobacco, 

 introduced into Europe about 450 years ago, which has become the 

 "sovereign master of practically all mankind"; coca, which yields 

 cocaine, a narcotic used by millions of addicts; cocoa or chocolate; 

 annatto, a vegetable dye, now used extensively for the coloring of 

 oleomargarine, butter, and cheese ; peanut, squash, pumpkin, and the 

 chayote ; and important fruits such as the pineapple, avocado, papaya, 

 guava, custard apple, and the sapodilla. 



It may be pertinent to point out here that all the basic food plants 

 upon which we are dependent came into existence in pre-Columbian 

 times. No new basic food plant has developed from the wild species 

 in either hemisphere since that time. The Concord, Catawaba, and 

 Delaware grapes derived from our native fox grape; the cranberry 

 derived from the wild species, long used by the Indians ; the modern 

 strawberry has resulted from hybridization of the North American 

 species and a Chilean species. The above grapes, cranberry, and 

 strawberry developed during the nineteenth century, and in the present 

 century the blueberry has been added. Important as they are, these 

 can scarcely be regarded as basic food plants. 



HOW DOMESTICATED PLANTS DIFFER FROM WILD SPECIES 



Domesticated plants differ from wild species in that the domesti- 

 cated species ordinarily cannot survive without human assistance, such 

 as planting (sowing or propagating), protecting, selecting, and pre- 

 serving. How these practices may best be accomplished is a major 

 concern of horticulturists and agriculturists. 



Heritable variation among seed plants is the rule rather than the 

 exception. The frequency of this variation may be high for some 

 species and low in others. The quality of the variation may range 

 from something that is of great value in survival of the species grow- 

 ing in the wild, to characters which are neutral, through degrees of 

 inhibiting influence to lethal variations. It should be kept in mind 

 that such variations occur in an individual plant of a species, and 



