84: EASY LESSONS IN VEGETABLE BIOLOGY. 



reach the lower limit of the rhododendron, gentian, 

 primrose, etc. The zone of pines comes next, to 

 6,000 feet. The zone of Alpine herbs extends to the 

 limit of perpetual snow, 9,000 or 10,000 feet. The 

 dwarf willow, a few rhododendrons, the mountain- 

 heath, and a single azalea are all the woody plants 

 of this zone in the Alps. The zone of cryptogams, 

 or the snow region, has only mosses and lichens, and 

 occasionally the " red-snow plant." 



