266 souriiEEN field crops 



122), ranging in Anicrican upland and long-staple upland 

 varieties from one half an inch to about two inches in 

 length. This varies somewhat with the variety, but varies 

 still more in different parts of the same plant. 



The boll stem should be of sucli length and diameter as will 

 prevent its bending abruptly, thus pre\'enting the most complete 

 development of the boll. 



It would probably be an advantage if the ItoU-stem should 

 be of sufficient length and strength to cause the l)oll to hang with 

 its tip downward, so that the leafy bracts might act against rain as 

 a roof, thus increasing the " storm resistance" of the seed cotton. 

 This, however, has not been proved ; for increased length may- 

 lead to a greater amount of breaking of boll-stems, rather than to 

 a normal drooping of the boll. It should be added that the 

 abrupt bending of the boll-stem is often due to a specilio disease, 

 ." black arm." 



235. Flowers. — The three green parts, which together 

 make the " square," are bracts or flower leaves, and serve 

 to protect the flower jjud. The l_)looms are large and pretty, 

 their size and color varying in different species. 



In American upland and long-staple upland, the liloom 

 is a pale cream color on the morning that it opens. On tJie 

 second day it changes to a pink or red and later falls. The 

 flowers open early in the morning and close late in the same 

 day. In Sea Island cotton, the young l)looni has a more 

 yellowisli tint than the flower of ujiland cotton. 



The pollen is heavy and waxy, and aiiparently it is 

 carried almost entirely by insects. However, cotton is 

 capable of self-fertilization, as shown by the fact that if a 

 hundred flower buds be inclosed by paper l)ags, bolls con- 

 taining seed will develop in most cases. It is probable that 

 cross-fertilization tends to increased vigor. At least the 



