PLATE XVIII 



Alnus incana (34a and 34b) 



Vessels present; vessels commonly in radial multiples; often 

 spring wood vessels are closely spaced singles or in irregular 

 clusters (some appearing as subdivisions of a single vessel), 

 the vessels progressing toward formation of radial multiples 

 from early to late wood; vessel perforation plates scalari- 

 form; axial parenchyma forming tangential bands at short 

 intervals between rays; rays uniseriate only. 



Alnus sinuata (35a and 35b) 



Vessels present; vessels commonly in radial multiples; often 

 spring wood vessels are closely spaced singles or in irregular 

 clusters (some appearing as subdivisions of a single vessel), 

 the vessels progressing toward formation of radial multiples 

 from early to late wood; vessel perforation plates scalariform; 

 axial parenchyma sparse and diffuse; rays uniseriate only. 



