STIPULE-SCAR 

 FlQ. 15 0'' WILLOW 



Fig. 17 



STIPULE-SCARS 

 OF TULIPTREE 



PULES (THORNS) OF 



BLACK LOCUST 



CONTINUOUS PITH 



DIAPHRAGMED PITH 



CHAMBERED PITH 



Fig. 18 



Fig. 19 



Fig. 20 



