SOME SPECIALIZING FLOWERS 113 



age forms a good blanket and shuts some of the 

 warmth in near the ground. As a result, a forest 

 region is never so hot nor so cold as a barren district 

 near by. This is noticeable in canyons a half mile 

 apart in the Tahoe Reserve. The valley of one 

 stream lately denuded of its timber is filled at night 

 with a cold fog which hangs low until the sun is 

 high next day. An adjacent canyon, with its pri- 

 meval forest untouched, is always free from this 

 chilly dampness. 



When the ground is well soaked with rain, you 

 know that the part which gets dry and hard first is 

 that exposed to the sun, and not that shaded by the 

 trees. Have you noticed that each leaf on the tree 

 is so arranged as to secure the greatest exposure to 

 the sunshine? This endeavor to get light produces 

 the different shaped leaves we find on the different 

 kinds of plants. The result is that, while the leaves 

 do not interfere much with each other's sunlight, 

 they do make greater shade over the ground. This 

 prevention of evaporation and the consequent stor- 

 age of moisture in the soil makes it possible for 

 many delicate plants to grow under trees months 

 after their sisters who chose the glade have perished. 

 You have learned this from observation. In sum- 

 mer you always seek ferns in woodsy spots. Have 

 you given the trees a thought of gratitude for their 

 service? 



