PLANTS 325 



layer of white wood which lies immediately under the 

 bark. The darker heart of the tree is composed of dead 

 fibers and serves as a storehouse for food and as a support 



Oak. Cypress. Southern pine. 



FIG. 286. Wood Grains. 



for the other parts of the tree. The heart of the tree 

 is most valuable for lumber, since it has a richer color 

 and decays slower than sapwood. 



The bark is the outer portion of the woody stem. The 

 part of the bark which is next to the sapwood is a living 



FIG. 287. Curly Walnut, Showing Grain in the Wood. 



