330 THE VALUE OF GREEN PLANTS TO MAN 



depend upon cotton to give employment to thousands of factory- 

 hands. 



Cotton. — Of our native plant products cotton is probably of 

 the most importance to the outside world. More than ten million 

 bales of five hundred pounds each are raised annually, although 

 the cotton boll weevil has greatly reduced the crop in some regions. 



Cotton-producing regions in the United States. Each dot = 4000 bales. 



The cotton plant thrives in warm regions. Its commercial 

 importance is gained because the seeds of the fruit have long fila- 

 ments attached to them. Bunches of these filaments, after treat- 

 ment or ginning, are easily twisted into threads from which are 

 manufactured cotton cloth, muslin, calico, and cambric. In ad- 

 dition to the fiber, cottonseed oil, a substitute for olive oil, is 

 made from the seeds, and the refuse makes fodder for cattle. 



Vegetable Fibers. — Among the important vegetable fibers 

 besides cotton are Manila hemp, which comes from the leaf-stalks 

 of a plant of the banana family, and true hemp, which is the bast 

 or woody fiber of a plant cultivated in most warm parts of the 

 earth. Flax is another important fiber plant, grown largely in 

 Russia, Ireland, and other parts of Europe. Flax is becoming a 

 more important crop in this country since the shortage caused 



