GRASSES OF IOWA. 



17 



the kernels in four, eight, ten and sometimes twelve, but most frequently 

 in ten rows. A comparison of these shows clearly the structure of the 

 ear. When there are only four rows, the ear is flattened and distichous, 

 and the opposite pairs of rows are evidently the result of the pairs of 

 spikelets regularly alternating upon the opposite sides of an extremely 

 short - jointed and 



flexuous rachis. In f J) C ^\ 



the eight-rowed ear 

 the rachis is four- 

 sided instead of two- 

 sided, and in the ten- 

 rowed it becomes 

 five-sided. This lat- 

 ter case corresponds 

 to the arrangement 

 in the terminal ra- 

 ceme of the stami- 

 nate inflorescence, 

 where the spikelets 

 are usually in five 

 ranks. In the eight- 

 rowed ear each joint 

 bears two opposite 

 pairs of spikelets, alternating with those of the joints immediately above 

 and below, and in the twelve-rowed there are three pairs to each joint, 



Fig. 9. Yellow Flint Corn. (Charlotte. M. King.; 



/ 2. 3 



Fig. 10. Left, Yellow Cuszco corn ; right, Brown Cuszco corn. (Charlotte M. King.) 

 2 



