DEBT OF AGRICULTURE TO AMERICA — COOK 495 



our extensive production places us quite definitely in the tropical 

 categ^ory. Our summer climate is essentially tropical in providing 

 sufficient heat for the maturity of these crops. The summer heat in 

 Europe is not sufficient to mature maize regularly north of the Alps, 

 and only a few localities in the south of Spain, Italy, and the Balkan 

 peninsula are warm enough for cotton. The European production of 

 cotton in 1929 totaled about 24,000 bales, while the southern coun- 

 ties of Virginia produced 4G,000 bales. On this basis Virginia is more 

 tropical than the south of Europe. 



The tropic of the geography passes below the southern tip of 

 Florida, but is only a conventional imaginary line. A plant-life tropic 

 would touch our east coast of North Carolina, follow the coast plain 

 to Texas, and continue westward through southern Arizona and Cali- 

 fornia. Botanists would not deny that countries with native palms 

 should be reckoned as tropical. The southern palmetto extends to 

 North Carolina ; two native palms are found in South Carolina and 

 four in Georgia. Louisiana, Texas, Arizona, and California, and 

 their endemic species of palms, Sahal louisiana, Inodres texana, 

 Washingtonia arwonica, and Washingtonia fllifera. The palm flora 

 of Florida, with more than a dozen native species, exceeds that of 

 many countries crossed by the Equator, to say nothing of the coco- 

 nuts in Florida, the dates in California, or the many ornamental 

 palms which are suited to open-air cultivation. 



The southern part of Florida, below Bradenton and Fort Pierce, 

 has frost protection for tropical perennials and tree crops, especially 

 near the coast. Most of the native flora of southern Florida is 

 essentially tropical, like that of the West Indies. Mangoes, avoca- 

 dos, sapodillas, bananas, papayas, and coconuts, with many other 

 palms and ornamental trees of distinctively tropical character, are 

 in regular cultivation. Recently it has been learned that all of 

 the more prominent rubber-producing trees, including the Hevea 

 or Para rubber tree of Brazil, are able to thrive in southern Florida. 



MAIZE OUR PREPONDERANT CROP 



The native agriculture of America had an essential unity and 

 continuity over both continents. From Canada in the north to 

 Patagonia in the south maize was the principal human food. The 

 local maize cultures were endlessly varied and differently combined 

 with other crops, but maize was the chief reliance over most of the 

 agricultural area. The native popidations of each district in trop- 

 ical America usually have several varieties of starch corns, some 

 for early and some for late planting, also pop corns and sweet corns, 

 which often are closely adapted to the local conditions. 



Many varieties from tropical American countries have been 

 brought to the United States and tested in different regrions. Under 



