THE LIFE OF THE LEAF 



the continued presence of the Red Maples of 

 Japan in garden and lawn. 



The last act in the life drama of the leaf is 

 the cutting off of the stem. In August a thin 

 plate of cork cells begins to form at the point 

 where the petiole joins the branch; this seems 

 to be a device to protect the tree from bleeding 

 when the leaf falls. Just outside of this cork 

 layer there forms a band of rounded cells lying 

 loose together with many empty spaces among 

 them. This is the abscissa or "cutting off" 

 layer; in some plants it shows as a pale ring en- 

 circling the petiole. By October everything is 

 ready — the valuable products of the leaf have 

 been withdrawn, the tree body is protected by 

 a layer of cork, the petiole is cut off and clings 

 only by a thread, so that when the winds beat 

 or the rain falls, the leaf parts company from 

 the tree and sinks quietly to its rest. 



In the light of this life story we comprehend 

 that the leaves are not slain by the frost, that 

 their death is a biological necessity, and that 

 their autumn colors are due to mechanical and 



133 



