54 THE TREE BOOK 



smooth-surfaced, thin-leafed trees prepare for 

 bed. The common locust is among the first to 

 say good night. She shifts her leaves so that 

 the end leaflet of each long cluster trails earth- 

 ward, while the side leaves dangle loosely in 

 rows, back to back. The honey locust raises 

 her leaves and folds them so that each little 

 leaflet partially covers the little mouths of the 

 one growing just above it. Other leaves, like 

 the willows, are raised upright ; still others fold 

 themselves along the middle, or turn edgewise. 

 Always the effort is to turn the broad surface 

 of the leaf as far as possible from the sky. 



Take hold of a sleeping leaf. How stiff it 

 is! We cannot make it keep any position but 

 the one it has chosen to take. Suppose we try 

 pinning some of the leaves in a horizontal posi- 

 tion. What happens? In the morning these 

 leaves are coated with dew, while the neighbor- 

 ing leaves, which were allowed to sleep, are 

 nearly dry. This proves that the imprisoned 

 leaves were much colder. So, you see, the sleep 

 of the leaves is a very important thing — often 

 a life or death matter to the baby leaves. 



How fast the little leaves grow! Long be- 

 fore our interest in them begins to wane, they 

 cease to be babies. But full-fledged leaves are 

 none the less interesting. An ideal leaf is made 



