ECONOMIC OR USEFUL PLANTS 397 



of the human race. It contains about seventy-five per cent starch, 

 but a low per cent of proteid matter, which is more fattening. 

 Rice is therefore a good food in hot climates. Most of the rice 

 in this country is polished by machinery with leather rollers 

 before it is put on the market. This pernicious practice removes 

 the outer layer, which is colored (a golden yellow in the Carolina 

 rice, and sometimes called the " bloom "), and also removes the 

 most nutritious part containing the proteids, as well as the flavor.* 

 561. Indian corn, or maize. This is a very important crop 

 in the United States. Maize (Zea Mays) was cultivated by the 

 Indian tribes in America from early times and is supposed to be 

 of American origin. It is now cultivated in Europe and other 

 countries (for botanical characters see Chapter XVII). Many 

 varieties are now known which are grouped in certain well-marked 

 types, as dent corn with a prominent indentation at the free end 

 of the grain, flint corn with smooth and very hard kernels, pop 

 corn noted for the sudden expansion of its grains into a large, 

 light, palatable mass under the influence of heat, and sweet corn 

 with its wrinkled grains containing sugar instead of starch as in 

 the other varieties. The United States produces four-fifths of 

 the Indian corn grown in the world. While it is grown over 

 quite a wide latitudinal range, it does not do well in the colder 

 temperate regions because of the short cool summers. It does 

 best in rich bottom or muck soil along river bottoms in warmer 

 climates, attaining a height of fifteen to twenty feet along the 

 Mississippi River and in the Southern States, or up to thirty 

 feet in the West Indies, while dwarf varieties with the flint grain 

 succeed better in the extreme northern latitudes of its range. 

 Besides the use of the grain as food for stock and man, it is the 

 source of much of the whisky in the United States and most of 

 the starch. Sixty per cent of the commercial starch is obtained 

 from the grains of corn. The grains of maize contain also about 

 five per cent of oil, and some attention is given to its extraction 

 for food and for commercial purposes. The blades make excel- 

 lent fodder, and the husks, pith and cobs are used in the 

 * See the National Geographic Magazine for April, 1906. 



