462 FIELD CROPS 



borne in panicles at the top of the stem and on the ends of 

 the side branches. The numerous and very small seeds ma- 

 ture in a few weeks after the blossoms appear. 



630. Composition. Tobacco is rich in plant food ele- 

 ments, containing about 6.7 per cent of nitrogen, 8.5 per 

 cent of potash, and 9 per cent of phosphoric acid. The upper 

 leaves average 2.5 per cent of nicotine, a poisonous alkaloid 

 which characterizes this plant. Tobacco is, therefore, an 

 exhausting crop, but, in turn, is itself good green manure. 



631. Types of Tobacco. Several distinct types of tobacco 

 are grown in the United States. The most important are 

 the cigar-leaf, white Burley, heavy, or export, and bright 

 yellow. The types are distinguished more by their uses 

 than by their botanical characteristics. Filler tobacco is 

 grown principally in Pennsylvania, Ohio, and the South, 

 and wrapper grades in the Connecticut Valley, Pennsylvania, 

 Wisconsin, and Florida. AVhite Burley is a distinct type 

 with light green leaves and cream-colored stems and midribs, 

 which is grown most largely in central Kentucky. Most of 

 this type is used in the manufacture of chewing tobacco. 

 In western Kentucky, western Tennessee, and the adjoining 

 sections of Illinois, Indiana, and Missouri, a type known as 

 heavy, dark, or export, tobacco is grown. This is a dark- 

 colored, thick-leaved type which is mostly exported to Europe. 

 In Virginia and North Carolina, the principal type is the 

 bright yellow, which is manufactured into smoking and 

 chewing tobacco. 



632. Importance of the Crop. The tobacco crop of the 

 world averaged 2,583,219,000 pounds annually for the five 

 years from 1907 to 1911. Of this crop, more than one third, 

 or 896,095,000 pounds, was grown in the United States. 

 Complete world data for later years are not available. Among 

 the other countries where tobacco is largely grown are British 

 India, with an annual crop of 450,000,000 pounds; Aus- 

 tria-Hungary, with 180,475,000 pounds; and Russia, with 



