CORN AND CLIMATE 73 



usually found to be either insuffcient or not properly distributed over 

 the long growing season. *Such is found to be the case when the 70 

 to 80 degree July isotherm of the northern latitude is traced around 

 the world. 



EFFECT OF CLIMATE UPON CHARACTER OF GROWTH. 



Corn displays a wonderful variability in its habits of growth. It 

 adjusts itself readily, though somewhat slowly, to changes in its 

 environment. This adaptability of the plant has resulted in a very 

 marked correlation between the manner of growth and the climatic 

 conditions under which it has been grown for a term of years. This 

 correlation is seen in 



1. The time of maturity and hence length of growing season. 



2. Size and nature of the stalks. 



3. Yield and character of the grain. 



The length of the growing season for corn varies from 90 to 160 

 days, and in different parts of the United States are found varieties 

 which are adapted to this wide range. According to Hunt, the rate of 

 shortening of the season as we go north of a given latitude is, in 

 general, about one day for each ten miles. The reverse is true as we 

 go south. Difference of altitude is said to retard plant growth and to 

 delay the awakening season between one-half and one day for each 

 hundred feet of ascent and vice versa. 



The length of the growing season is in general the most important 

 factor in determining the size of the stalk produced. The long sea- 

 son of the south induces the growth of tall, massive stalks with large 

 yields of both fodder and grain, while the shorter northern season in- 

 duces a small, stunted stalk with a moderate yield of grain. The 

 larger stalks are coarser and more woody in structure, while the 

 smaller ones are much less so, and produce a better quality of fodder. 

 Accompanying these differences in the stalk are corresponding differ- 

 ences in the grain. The southern corn has large ears with long, deep 

 kernels, possessing a deep, pinched dent and a structure that is in- 

 clined to be starchy. On the other hand as we go north the opposite 

 of these characters is seen. The dent grows shallower and smoother 

 and the kernels shorter and more horny and flinty, until they merge 

 into the characteristic Flint corn of the north. The differences seen 

 in these respects between sections no further separated than the north- 

 ern and southern parts of Iowa and Illinois are very marked, while 

 beyond the borders of these states the differences are still more no- 



*Hunt'a "Cerosla in America," Page 203. 



