208 Bulletin 194 



ff. Ray cells (radial) about twice as long as high; vessels 

 (longitudinal) not plugged at intervals with dark red 

 gum; color light brown to reddish. 



g. Wood cream-white, without reddish tinge ; rays 

 (radial) not conspicuously darker than surrounding 

 wood; growth rings (cross) usually very wide, 



Acer negundo. 



gg. Wood light red-brown to decidedly reddish; rays 



(radial) conspicuously darker than surrounding 



wood; growth rings (cross) usually moderately wide 



to narrow. 



h. Larger rays (tangential) 4-6-seriate, for the most 

 part broader than the pores (cross) ; pith flecks 

 absent or rare ; growth rings more or less distinct ; 

 wood very heavy and hard, 



Acer saccharum, p. 223 

 Acer saccharum nigrum. 

 hh. Larger rays (tangential) 2-3-, or occasionally 4- 

 seriate, mostly narrower than the pores (cross) ; 

 pith flecks present, often abundant; growth rings 

 for the most part indistinct ; wood rather light and 

 soft. 



i. Pores (cross) barely visible to the naked eye 

 with close scrutiny ; pith flecks (cross) usually 

 small, neither abundant nor conspicuous, 



Acer saccharinutn. 

 ii. Pores (cross) visible to the naked eye with close 

 scrutiny; pith flecks (cross) usually rather large, 

 sometimes abundant, more or less conspicuous, 



Acer rubrum. 

 dd. Rays (cross) not uniform, some of them conspicuously 

 broad. 



c. Rings (cross) strongly sinuous; wood white, not showing 

 marked graining on tangential- and radial-sections ; broad 

 rays (cross) confined to short radii of the concave por- 

 tions of the rings Carpinus caroliniana. 



ee. Rings (cross) regular, not strongly sinuous; wood brown- 

 ish to reddish, showing marked graining on tangential- 

 and radial-sections; broad rays (cross) uniformly dis- 

 tributed, not confined to short radii. 



