48 THE PRINCIPAL SPECIES OF WOOD. 



lighter-tinted wood. The nuts of the walnuts are a source of 

 profit. 



Black walnut trees seldom form forests by themselves, but 

 occur generally in mixed growth. They grow quickly, but the 

 heartwood for which the tree is valued begins to form only 

 when the tree is at a considerable age, so that a number of 

 years must elapse before a tree can produce wood of the 

 desired quality. Trees one hundred years old furnish the best 

 quality of wood. 



Walnut trees may be known by their nuts, the husks or 

 pods of which adhere unbroken, instead of loosening, com- 

 pletely divide into four sections, as with the hickories. 

 Juglans is from Jovis, signifying Jove's, and glans, signifying 

 acorn. This nut, not the fruit of the oak, was the acorn of 

 the ancients.* 



* The ancients considered the shade of the walnut as harmful to all life. It is 

 certain some vegetation is affected, probably by properties in fallen leaves. 



