418 PRACTICAL BOTANY 



height of over 22 feet. Some corn in Paraguay is said to ripen 

 in one month, while Illinois field corn requires from four to 

 five months. 1 



Six well-defined types of corn are recognized, but only four 

 are of much economic importance. These are pop corn, with 

 small kernels and endosperm all or nearly all horn-like ; flint 

 corn, with much horn-like endosperm and a grain too hard to 

 be fed to most animals without being ground ; dent corn, with 

 the kernels indented at the outer end : and sweet corn, in which 



FIG. 332. A prize ear of " Johnson County White " corn 2 

 An admirable type of dent corn. Photograph by L. B. Clore 



most of the starch of the endosperm is replaced by a kind of 

 sugar. Of these four kinds, dent corn is by far the most im- 

 portant, constituting the great bulk of the crop in the corn 

 belt. Each of the types of corn has many varieties ; of dent 

 corn alone more than three hundred have been named and 

 described. Most of these varieties are found to show slight 

 variations, which make them more or less desirable for the 

 corn grower, and his efforts must be directed mainly to im- 

 proving the quality of existing kinds. 



1 See Bulletin 57, Office of Experiment Stations, U. S. Dept. Agr., 1899. 



2 This ear of corn was bid in by the grower (Mr. Clore) at an auction sale 

 of exhibits at the Chicago National Corn Exposition in October, 1907. The 

 price paid was $250. 



