78 



A TEXTBOOK OF BOTANY 



[Ch. Ill, 9 



Another special form and function of leaves is represented 

 in the brown bud scales which enwrap the winter buds of 

 our trees. They mostly lack chlorophyll, their cell walls 

 become thick and well cutinized, and often they develop 



Fig. 51. — Forms of leaf tendrils ; X \. Pea, Smilax, Bignonia, Clematis, 

 Laihyrus Aphaca. The apparent leaves of the latter are stipules. 



coatings of resin or hairs ; and they fall away as the buds un- 

 fold. In some kinds each scale is an entire leaf, in others 

 it is a petiole with blade suppressed (Fig. 53), or it may be a 

 stipule, as conspicuous in Tulip tree, where together the pair 

 forms a close-fitting cap (Fig. 57). 



