18 CORN CROPS 



like maize. While it grows to a height of five to ten feet, 

 the stem is slender and the leaf about half the width of 

 the maize leaf. The plant bears a tassel-hke structure 

 at the top and on the lateral branches, closely resem- 

 bhng the maize tassel, except that the seeds are borne 

 on the lower part of each tassel and the pollen on the 

 upper part. 



Teosinte, which is sometimes cultivated but does not 

 matm-e north of Mexico, is more like maize than is gama 

 grass, the plant being larger and the terminal tassel bear- 

 ing pollen only. The lateral branches of the plant are so 

 shortened that the terminal tassel-like structure is borne 

 in a leaf axil, surrounded by a kind of husk as is an ear 

 of maize, and bears only pistillate flowers, or seed. It is 

 only a step in the production of an ear of maize, from 

 teosinte, by a development of the central spike of the 

 lateral tassel into an ear. 



It is probable that the early progenitor of maize was a 

 grass-like plant having a tassel at the top and tassel-like 

 structures on long, lateral branches, all tassels bearing 

 perfect flowers. As evolution progressed, the terminal 

 tassel came to produce only pollen, and the side branches 

 only ovules, or seeds. Evolution often results in a greater 

 " division of labor," as in this case. At the same time, the 

 lateral branches were shortened or telescoped into the 

 leaf sheaths, these sheaths forming a covering, or husk, 

 for the ear. Also it is probable that in this evolution the 

 central spike of the tassel developed into an ear. 



The close relationship of maize and teosinte is proved 

 by the crosses that have been made between the two. In 

 the third or fourth generation after crossing, a peculiar 

 type of corn is secured, identical with a type of maize that 

 has been found growing wild in Mexico {Zea canina), and 



