CHAPTER XLVI 

 THE ECONOMIC BIOLOGY OF PLANTS 



Vocabulary 



Economic, pertaining to man's use. 

 Solvent, a substance used to dissolve others. 

 Utilize, to use. 



Economic biology deals with the relation of living things to man, 

 either for use or for harm. The " economic importance " of a plant 

 or animal does not mean merely its value to man, but also includes 

 any way in which it may damage him. Usually the uses out- 

 number the injuries, but do not forget that both are included. 



General Uses of Plants. 



1. To supply oxygen and remove carbon dioxide in photo- 

 synthesis. 



2. To aid in returning nitrogen compounds to the soil. 



3. To regulate drainage of water (forests). 



4. To supply foods for man and animals. 



5. To provide fabric fibers (cotton, linen, hemp). 



6. To provide fuel (wood, peat, and coal). 



7. To provide paper materials. 



8. To provide timber, cork, rubber. 



9. To provide tanning materials (hemlock, oak and other barks) . 



10. To provide dye stuffs. 



11. To provide drugs and medicine, alcohol. 



12. To provide turpentine, wood alcohol, acetic acid. 



To balance this long list of uses for plant products, there are 

 but few ways in which they ever harm mankind. Some of these 

 have been studied in Chapter 17. 



Of course bacteria head the list of harmful plants, in that they 

 cause many diseases, but do not forget that most bacteria are 



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