The External Features of Stems 127 



In the cherry and birch the lenticels persist for many years and 

 become elongated transversely, forming rough granular rings 

 part way around the stem. In the trunks of thick-barked trees 

 the lenticels occur in the furrows of the bark. 



PROBLEMS 



1. Find out how your local gardeners trim their grapevines, berry bushes, and fruit 



trees. Secure definite information for five of these plants, and determine 

 the reasons underlying the practices. 



2. Remove the scales from various buds in December and determine how long the 



unprotected buds live. What weather conditions are most unfavorable 

 to uncovered buds? 



