84 SOUTUEPtN FIELD CROPS 



provided with an arrangement ))y which, in drj' weather, 

 the size of the opening is reduced, thus decreasing the 

 amount of water thrown off bj^ the leaf. 



The' corn leaf has also another means of economizing in the 

 transpiration of moisture. This is seen in the rolling together of 

 leaves in the middle of a hot dry day. This curling, or rolling, . 

 of the leaves is due to the presence of special cells, which, on 

 parting with a portion of their moisture in dry ^A'eather, cause the 

 leaf to fold inward. 



In the South, the corn plant is especially liable to lose pre- 

 maturely the use of its leaves through their drying, or "firing." 

 This may be due to dry weather, to inadequate preparation of the 

 soil, to lack of proper culti\'ation, to root pruning, or to other 

 causes. 



The leaf consists of two principal parts : the sheath, or that 

 part which is clasped around a portion of the stem, and the blade. 



Fi(i. .33. — Part of \ Corn Le.\f, suowixu \\ avy ^Iargixs. 



or free part of the leaf. The outer margin of the blade is waA-y 

 or scalloped (Fig. 33). This permits tlie leaf to turn from the 

 wind like a windmill thrown out of gear, and thus to s.\o\A 

 throwing too great a strain on the stem. 



84. Ear-branch and shucks. — Tlie shank on which the 

 car is borne reiwesents a branch. That this is a branch is 

 api^arent (1) from its position in tlie angle fietween the 

 stem and the leaf-sheath ; (2) by the fact that the shank 

 has nodes similar to those of the main stem ; and (3) by 



