PART VI. LIFE UPON THE EARTH 



CHAPTER XXVII 

 THE PLANT COVERING OF THE EARTH 



318. Questions for Discussion. 1. See if you can learn what the 

 chief features of the native-plant covering of your region were before 

 men began to cultivate it. How much of this native plant life now re- 

 mains? Was it right to remove it? 2. If you have swamp lands, dry, 

 hilly regions, and regions of medium conditions in your community, 

 state what characteristic differences there are in these three types of 

 regions. What makes the differences in plant life? 3. Can you prove 

 that plants and erosion are gradually filling the lakes and swamps and 

 may eventually make them into tillable fields? 4. Make a list of the 

 uses of plants which you encounter in one day. 5. What wild plants 

 growing in your neighborhood are of value ? 6. Secure, if possible, the 

 value or amount of the principal crops of your community. 7. What 

 industries in your town depend mainly upon plants for their existence? 

 Which do not depend upon plants at all ? 8. Would it be wise to allow 

 the original native-plant growth to remain in good agricultural land? 

 9. Are there any areas in your community which might hare been 

 more valuable if left covered by native vegetation? Why? 10. Why 

 are plants killed when salt brine is poured upon their roots? 11. Ex- 

 plain what occurs when dried raisins or prunes placed in a dish of 

 water soon become plump in form. 



319. Abundance of plants. In the preceding chapters there 

 has been frequent reference to living things, and some of 

 them, such as bacteria, have been studied. Almost every- 

 where the 'surface of the land is covered with plants, if they 

 have not been removed by man ; and even where this has 

 been done, man has usually introduced other plants to take 

 the place of those he has removed. In countries with abun- 

 dant rainfall they hide the earth so completely that the 

 landscape is almost wholly green. Even in the desert there 



315 



