PLANTS FROM AN ECONOMIC STANDPOINT 339 



which is exposed to weather ; basswood, for work demand- 

 ing lightness ; ash, where strength, lightness, and straight 

 grain are desired; oak, cherry, mahogany, rosewood, 

 and walnut for furniture ; and so on through the large 

 list of woods. 



Trees also furnish a number of other valuable products, 

 such as turpentine, resin, tar, creosote, cork, maple 

 sirup, and some acids and oils. 



Other Uses of Trees. It is gratifying to note the 

 increased attention which our cities are giving to the 

 question of trees. In 

 a large number of our 

 cities we have park com- 

 missions, and in a few 

 cities we have city for- 

 esters whose duties are 

 to look after the planting 

 and protecting of trees 

 (Figure 301 ). Some rea- 

 sons w T hy trees should 

 be planted in a city are : 

 they purify the air ; they 

 enhance property values ; 

 they make the city more 

 beautiful ; they cool the 

 air in summer by the FIG. 301. A Good Example of Tree 

 evaporation of moisture 



from their leaves ; they provide shade for lawns and pave- 

 ments ; they attract birds ; they have an educational and 

 patriotic influence upon the citizens. 



Food Plants. Nearly all our food comes directly 

 or indirectly from plants. Sometimes it is the root we 

 eat, sometimes the stem, sometimes the leaves, the 



