346 



PLANTS AND MAN 



and Ireland, which lead the world in flax culture. Until forty 

 years ago, almost every United States farmer grew fiber flax for 

 his own use, but this has been largely discontinued, and at the 

 present time no commercial fiber flax crops are grown in the 

 United States. 



Flax fibers are located in the thin bark which covers the stem, 

 and consist of tough strands, sometimes three 

 feet long, made up of cells with heavy cellulose 

 walls. The plants are usually harvested by 

 pulling, and then either submerged in water 

 or allowed to lie in the field exposed to dew, 

 rain, and snow until bacterial decomposition 

 has loosened the fibers from the bark and 

 wood. The debris is then removed from the 

 fibers by the rolling and beating action of 

 special machines after which the fiber is 

 combed and straightened, either by hand or 

 machine. Long straight fibers are spun into 

 thread used for high grade linen fabrics, 

 while short and tangled fibers (tow) are used 

 in flax yarns and in coarse fabrics. Linen 

 threads, fabrics, and yarns are famous for 

 their great strength, which increases when 

 they are wet. Linen fabrics conduct heat more 

 rapidly than others, and therefore are more 

 desirable for summer clothing, the body heat being easily dis- 

 sipated into the surrounding air. 



I 



Fig. 231.— Flax 

 plants are slender 

 annuals with small 

 white or blue 

 flowers. 



Hemp is also a very ancient cultivated plant, though probably 

 not as old as flax. It was introduced into Europe from China 

 about 1500 B.C. and the industry today centers in Russia, Italy,, 

 and Hungary. In this country small amounts are produced in 

 Wisconsin and Kentucky. 



The hemp plant is a tall hollow-stemmed annual which 

 grows to be sixteen feet high (fig. 232). Its flowers are small,| 

 maturing to form the hemp seed which yields a fatty oil. The dried? 

 flower tops yield a powerful narcotic drug which is discussed in 



