PLATE XXI 



Arctostaphylos uva-ursi (39a, 39b, and 39c*) 



Vessels present; vessels solitary, in pairs, or in various 

 aggregates; annual ring initiated by a definite band of large 

 vessels; other vessels are much smaller and sparse, giving 

 a two-banded appearance to the growth ring; perforation plate 

 simple; axial parenchyma few, if in contact with a vessel, a 

 single cell rather than an encircling band; rays one or two 

 cells wide (rarely three). 



Ledum glandulosa (40a and 40b) 



Vessels present; vessels solitary, in pairs, or in various 

 aggregates; vessel perforation plates scalariform; rays uni- 

 seriate only. 



