X. THE ECONOMIC RELATION OF GREEN PLANTS 



TO MAN 



Problems. — How green plants are useful to man. 

 {a) As food. 



(b) For clothing. 



(c) Other uses. 



How green plants are harmful to man. 



Suggested Laboratory Work 



If a commercial museum is available, a trip should be planned to work 

 over the topics in this chapter. The school collection may well include 

 most of the examples mentioned, both of useful and harmful plants. 



A study of weeds and poisonous plants should be taken up in actual 

 laboratory work, either by collection and identification or by demon- 

 stration. 



Green Plants have a " Dollar and Cents " Value. — To the girl 

 or boy living in the city green plants seem to have little direct 

 value. Although we see vegetables for sale in stores and we know 

 that fruits have a money value, we are apt to forget that the wealth 

 of our nation depends more upon its crops than it does on its 

 manufactories and business houses. The economic or " dollars 

 and cents " value of plants is enormous and far too great for us 

 to comprehend in terms of figures. 



We have already seen some of the uses to mankind of the 

 products of the forest ; let us now consider some other plant 

 products. 



Leaves as Food. — Grazing animals feed almost entirely on 

 tender shoots or leaves, blades of grass, and other herbage. 

 Certain leaves and buds are used by man as food. Lettuce, 

 beet tops, kale, spinach, broccoli, are examples. A cabbage 

 head is nothing but a big bud which has been cultivated by 



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