SUNLIGHT FACTORIES 
5 1 
Only an expert can tell the age of living trees 
unless they are pines or spruces. Anyone can 
count the circles of branches on these trees. If 
there are ten rows, the tree will be ten years 
old. But anyone with sharp eyes can tell the 
age of a tree that has been cut down by 
counting the rings in the end of the log. Each 
ring stands for a year’s growth. The part 
nearest the center of the log is the oldest, and 
that nearest the bark is the newest. The grow¬ 
ing part of the tree is just under the bark. It 
is called the cambium (pronounced kam'- 
bi-um). The working parts of the tree trunk 
are near here also. Next to the cambium, on 
the inside, are the tissues that carry water up the 
tree. On the outside of the cambium, nearest 
to the bark, are the tissues that carry the food 
from the leaves to any part of the tree that needs 
it. All during the growing season, the cam¬ 
bium works very hard, forming new water¬ 
carrying and food-carrying tissues. Mixed with 
the water carriers are wood fibers also. Some¬ 
times the trunk becomes so much larger that it 
The age of a tree can 
om the stump 
How can we tell 
the age of trees? 
