PINE TREE 87 



the central stem grows a new length and forms a new circle of 

 side branches. Also each side branch grows and branches in 

 the same way as if it were the main stem." 



In a pine tree, the part above any circle of branches looks 

 nearly as the whole tree did when it was the age of that part. 

 In a large tree, count down five circles of branches from the top, 

 and see if the part above the lowest circle is not a perfect five- 

 year-old tree. By counting the circles of branches you can tell 

 the age of a pine tree. In the oldest tree there are always 

 some parts that are only a year old. What parts are they ? 



In spruce and fir trees the branches grow even more regu- 

 larly than in the pine. 



Why Many Pine Limbs die. — After a pine has grown in a 

 regular way for four or five years, its branches begin to crowd 

 one another. Then some of them die from want of space, sun- 

 light, and food, and some more are killed by winds and insects. 

 So no tree grows exactly after its plan. Yet even an old tree 

 plainly shows its plan of growth on the ends of its branches, 

 while numbers of dead twigs on its trunk and larger branches 

 show wdien and how it tried to follow its model. Why are 

 there more dead branches on a forest pine than on a pine 

 tree that has grown in a field ? 



Where a Tree grows in Length. — If you drive a nail into 

 the trunk of a growing tree, Avill it be lifted farther and farther 

 from the ground as the tree grows taller ? By the end of each 

 year each length of new wood is hard and fully formed, and 

 can not be made longer. So the limbs always keep the same 

 distance apart, and no limb or piece of old wood is lifted up 

 from the ground. The limbs seem to be lifted up because the 

 lower ones die. A tree grows taller only because new lengths 

 of wood grow on the outer ends of the old wood. 



Why are the branches farther apart on an old tree than on 

 a young one ? Why are the upper branches nearer together 

 than the lower ones ? Why can you not see the remains of 

 any dead branches low down on the trunk ? 



