90 NORTH AMERICA 



acacia) and other similar leguminous trees, such as 

 gleditschia and gymnocladus. 



On the dry limestone heights of Tennessee there are 

 forests of tall junipers, producing that excellent red 

 wood which serves for pencils. The so-called 'cedar- 

 glades' continue down to Alabama, and forests of this tree 

 are also found in Florida. Gradually, however, as one 

 goes south, the number of evergreen trees and shrubs 

 increases. Mixed forests of summer-green and evergreen 

 components now mark a step towards the sub-tropical 

 vegetation of the southernmost States, and evergreen 

 magnolias become abundant. 



The low and broad alluvial plain of the Mississippi 

 valley, across which the mighty river has thrown vast 

 swamps, with a dense network of sluggish, meandering 

 arms called ' bayous ', is particularly well irrigated and 

 fertile. It is difficult to distinguish the forests which 

 cover it either from the sub- tropical rain -forests or from 

 the summer-green type of the plateaus ; the Mississippi 

 valley offers all transitions from one to the other with 

 a tendency towards the luxuriance of the south. A long 

 way up the river, the bayou country favours the ex- 

 tension of the rain-forests into the cooler regions. 

 Beyond the plain of the Mississippi, according with a 

 gradual decrease of rainfall, the higher plains of Arkansas 

 and eastern Texas possess lighter and poorer woodlands, 

 which herald the approach of the western prairies. 



The vast region which extends from the Appalachians 

 to the prairies is one of the largest granaries of the 

 world. Agriculture, in spite of the intrusion of other 

 industries, continues to play an important part in the 

 life of the country ; owing to the wealth of water- and 

 rail-ways, it is afforded an almost unlimited scope. 

 Wheat in the north, maize south of the forty-second 



