80 EASY LESSONS IN VEGETABLE BIOLOGY. 



CHAPTER XII. 



THE VEGETABLE CLOTHING OF THE WORLD. 



1. THE beautiful forms of vegetable life, and the 

 peculiarities of different species, give character to the 

 landscape scenery of the world, and the comparison 

 of the different floras (or groups of plants) on the 

 earth's surface will aid us greatly in our biological 

 generalizations. 



2. The study of the distribution of plants over the 

 earth is sometimes termed Botanical Geography. It 

 has been greatly promoted by the travels of Hum- 

 boldt. Standing a few hundred feet below the sum- 

 mit of Chimborazo, he saw an epitome of the vegeta- 

 tion of the globe a picture of all climates from the 

 tropics to the poles, with their zones or belts of vege- 

 tation. Just above him rose the inaccessible summit 

 of snow a beautiful image of purity set in the cloud- 

 less blue of a tropical sky. The only vegetation present 

 was the Red Snow, or a few Thallogens. The vol- 

 canic rocks around him were draped with Lichens, a 

 few Mosses, and Alpine flowers. Beneath, the grass- 

 green slopes, with varied flowers and willowy shrubs, 

 were succeeded by forest belts, and these latter by the 

 tropical luxuriance at the base of the mountain. 



