THE NORTH TEMPERATE ZONE 



67 



The region about the Persian Gulf is supposed to be the original 



home of the date-palm, now so extensively cultivated in Arabia 

 and northern Africa, and recently introduced into the hottest 

 parts of southern California and Arizona. 



Asia Minor is extraordinarily interesting historically, as the 

 alleged cradle of the human race, and has been inhabited from 

 earliest historic times. It is almost certain that the ancestors of 

 the most important European cultivated plants were derived from 



jfe^tfSr- ' - 



Fig. 14. — Sandy desert, northern Sahara. Photo., Dr. W. A. Cannon. 



species indigenous to this region. Wheat, barley, the vine, fig 

 and pomegranate are still represented by wild species which were 

 the probable progenitors of all the varieties now in cultivation. 



The dry steppes are surrounded by mountains, some of great 

 elevation, like the Caucasus and Lebanon, and the highest eleva- 

 tions are covered with perpetual snow. These mountains in many 

 regions, have a well-developed forest belt, and a true alpine flora. 



In the mountain forests of the Balkan regions, and the Caucasus 

 are a number of trees, absent from central Europe 1 and the northern 

 Mediterranean. Among these are several conifers, firs and sprue 3, 

 but in addition genera quite absent from Europe The- walnut 



