FLORA OF SOUTH AMERICA. 



83 



same effect is produced by the altitude of the mountains. Numerous summits, 

 and, in fact, all the Cordilleras taken as a whole, rise in the cold atmospheric 

 regions above the forest zone. As a rule, the upper limit of this zone lies at 



Fig. 12. — Deudk's Main Botanical Ditisions of South Ameeica. 

 Scale 1 : 57,000,000. 



about 3,000 feet below the snow-line. Under the equator and in Bolivia forests 

 still reach an elevation of 11,500 feet on the flanks of the mountains. But 

 above them plants of Ioav growth range right up to the edge of the snows, and 

 even higher in those spaces where the snows have been cleared by the winds 

 4 



