i 7 8 



THE ANATOMY OF WOODY PLANTS 



the wood of the red oak, Quercus rubra. Large rays are plainly 

 present which differ from those found in the alder by the fact 



that, instead of 

 being composed of 

 a mixture of 

 smaller rays and 

 separating fibers, 

 they are consti- 

 tuted entirely of 

 parenchymatous 

 elements. In spite 

 of this difference in 

 the organization of 

 the broad bands of 

 radial parenchyma 

 they are correlated 

 with the same dips 



in the annual rings 

 FIG. i 3 i.-Tangential section of stem of Alnus found j n ^ aWer 

 japonica, showing leaf trace imbedded in the aggregate _, 



ray to which it is related. as described in the 



foregoing paragraph. 

 In Fig. 133, p. 180, 

 is shown a trans- 

 verse section of a 

 branch of the velvet 

 oak. Here there are 

 five pairs of rays 

 corresponding to the 

 five faces of the five- 

 angled pith, which 

 by its configuration 

 indicates the phyllo- 

 taxy precisely as 

 does the triangular 

 medulla in the alder. 

 In the oak there are 



FIG. 132. Transverse section of the wood of the red oak 



