Trees, Stars, and Birds 



Cone-shaped trees. A young tulip tree growing in 

 the open is beautifully symmetrical and distinctly cone- 

 shaped. A young sycamore, pine, or cedar has the same 

 shape. Why do the lower branches on these trees grow 

 out longer than the upper branches ? What is the func- 

 tion of the leaves on a tree and what would happen to 

 the leaves on the lower branches if these branches were 

 not longer than the upper ones ? Why do not the lower 

 branches of a Lombardy poplar find it necessary to grow 

 out horizontally and widen the lower part of the crown? 



To estimate the height of a tree. WTien we look at 

 one of our great tulip trees, we often wonder what the 

 height of such a tree is. This can be determined in a 

 very simple way without climbing the tree. 





FIG. 50. Leaves and flower of the long-leaved magnolia. The magnolias 

 are dose relatives of the tulip tree and are favorite shade trees in the South. 



