THE VEGETATIVE STRUCTURES 



8i 



being due, in some degree, to tiny lichens which do not 

 attack the leaves until they are about a year old. When 

 the leaves first break through the bud scales they are 



Fig. 27. — Dioan spinulosum: tangential longitudinal section of 

 mature wood, showing elongated woody fibers (tracheids) and four rays. 



perfectly erect (Fig. 28), but soon spread out into an 

 oblique position, which they maintain for a year or 

 more; afterward they begin to droop but may retain 



