PLATE XV 



Acer glabrum (30a, 30b, 30c**, and 30d*) 



Vessels present; vessels commonly in radial multiples; often 

 spring wood vessels are closely spaced singles or in irregu- 

 lar clusters (some appearing as subdivisions of a single ves- 

 sel), the vessels progressing toward formation of radial 

 multiples from early to late wood; vessels with spiral thick- 

 enings; perforation plates simple; rays composed of procum- 

 bent cells only; rays mainly uniseriate but some two to four 

 cells wide. 



36 



