432 



GENERAL BOTANY 



been cultivated and greatly 

 improved by man. Corn, 

 for instance, is supposed to 

 have been derived from a 

 wild grass or to be a hybrid 

 between two grasslike an- 

 cestors. The wild wheats 

 of Palestine, from which 

 the cultivated varieties are 

 supposed to have come, are 

 essentially grasses in which 

 the fruit is a grain of the 

 greatest value to man for 

 flour. All the other cereals 

 have originated similarly 

 from the grasses and have 

 been gradually improved 

 by methods of culture de- 

 scribed in the chapters 

 on hybridization, selection, 

 and evolution. 



In addition to the grasses 

 and cereals the grass fam- 

 ily includes sugar cane 

 (Fig. 277) (used for mak- 

 ing sugar), bamboo (used 

 for fishing rods), and rice 

 (used as a food plant). 



Reproduction. The flow- 

 ers of the grasses are usu- 

 ally very highly modified, 

 and their relation to the 

 flowers of the monocoty- 

 ledons thus far studied is 

 difficult to determine. In 

 the corn plant (Fig. 102) the flowers are borne separately, the 

 staminate flowers forming a compound inflorescence, known as 



FIG. 279. Structure of an ear of corn, or 

 pistillate inflorescence 



A, section of a young ear, showing the cob, or 

 axis of inflorescence (ax), and the silk, or style, 

 and stigmas (si) ; B, ovary, showing ovule (o), 

 and style ; C, upper portion of style (silk) and 

 stigmas, enlarged 



