332 INTRODUCTION TO BOTANY 



PROBLEMS 



1. What is it that often causes suddenly submerged agricultural 

 plants to become yellow and die? 



2. What causes the bubbles that arise from the soil when a heavy 

 shower is falling ? What causes them to rise ? 



3. What are the worst plant diseases of your community? What 

 has your state done to prevent these diseases ? Do people in your com- 

 munity follow the directions of your agricultural experiment station 

 relative to plant diseases? 



4. What is the source of the dust that is deposited on window sills 

 during windy weather ? 



5. Are soils blown away during windy weather? 



6. Why are the branches of young trees pruned so heavily when 

 the trees are transplanted ? Why are they pruned as a means of fruit 

 production ? 



7. Why do agriculturists ordinarily use low or level lands chiefly for 

 cultivation and uplands chiefly for pasturage ? 



8. What effect upon the soil is supposed to be produced by rotation 

 of crops ? Is rotation advisable for the garden ? 



