u 



PLANT STUDIES 



Fig. 36. A branching hair from the leaf of common mullein, showing the outline but 

 not the many cells. 



comparatively thick, although they may be very numerous 

 (see Figs, i, 172). In this way each leaf exposes a small 

 ,..:. surface to the dry- 



ing air and intense 

 sunlight. In our 

 southwestern dry 

 regions the cactus 

 a b o u n d s , plants 

 which have reduced 

 their leaves so much 

 that they are no 

 longer used for 

 chlorophyll work, 

 and are not usually 

 recognized as leaves. 

 In their stead the 

 '"'■■> ''.-■■ : '''fi\- globular or cyhn- 



■'■■'■- ^'''I'iV'-}-' drical or flattened 



Fig. 37. A scale from the leaf of Shepherdia. These senlsale green and 

 scales overlap and form a complete covering. do leal Work (higS. 



