106 



PLANTS AND MAN 



living gregariously has made it possible for them to populate 

 almost exclusively the central plains of the United States to form 

 one of the dominant features of our vegetation — the prairies. 

 All of the cereal grains as well as sugar cane belong to the Grass 

 Family. 



Fig. 74. — -Joshua trees are members of the Lily Family which are grotesque 

 denizens of our arid southwest. 



Two of the most conspicuously flowered families of the entire 

 phylum are found in the Monocot sub-class; they are the Orchid 

 and the Lily families. In the latter are the few trees which grow on 

 our southwestern deserts, the Joshua Trees or Tree Yuccas (fig. 

 74). The Palm Family is the only family which has persisted in 



