200 Our Field and Forest Trees 



tight-fitting hole in a sheet of cardboard, into a 

 glass of water. Cover the twig with an inverted 

 glass, wiped clean and dry. Let it stand for 

 twelve hours. Notice the moisture which gathers 

 on the inside of the inverted glass. Then try the 

 same experiment over — after stripping the leaves 

 from the twig." (Jackson: Forestry in Nature 

 Study. ) 



Plants of sun-beaten lands are threatened with 

 a double danger. Their juices may be parched up 

 by heat — and the intense light, if it beats on the 

 leaves, may destroy the chlorophyll. The leaves 

 of such plants are like Robinson Crusoe, who wore 

 clothes on his hot desert island to protect his skin 

 from the blazing sun. 



The sagebrush of the dry plains is clothed all 

 over with short hairs, and a like covering protects 

 the desert willows from the burning light. Many 

 of the desert plants look hoary, rusty, or silky, 

 because they are so thickly covered with down 

 which acts as a sun screen. Willows of the far 

 north wear coats of down too, but, in their case, 

 it serves as blanketing. Their spray tips and 

 young leaves are silvery white with vegetable fur, 

 which fits them for life in Labrador. 



In most plants growing on land, the stomata of 

 the leaf are in its lower surface, and in many cases 

 they are all there out of reach of the direct sun. 



Beside putting the little mouths on the shad- 

 owed side of the leaf, nature has covered them a 



