88 



THE ANATOMY OF WOODY PLANTS 



C. stricta. It is evident from the photograph that a mass of ray 

 tissues on the left (representing the end nearer the pith), charac- 

 terized by moderate breadth and the absence of vessels, passes 

 toward the right (outer side topographically) into a continually 

 widening fanlike cluster of rays among which vessels become more 

 and more prominent. Fig. 70 shows a tangential, longitudinal 

 section of the wood in a small branch of C. equisetifolia. Here is 



present an aggrega- 

 tion of rays, foliar 

 in its character, 

 which as yet has 

 scarcely begun to 

 diverge into the 

 diffuse condition 

 and consequently 

 includes no vessels 

 in its substance. 

 C. stricta and C. 

 equisetifolia are 

 both species with 

 the diffuse type of 

 ray in the adult 

 wood. C. stricta 

 has been chosen to 

 illustrate the trans- 

 verse aspect of the 

 diverging rays in 



the diffuse type only because the larger size of the radial bands 

 in this species make the topographical relations more obvious. 

 The difference in gross appearance between stems with aggre- 

 gate or compound rays on the one hand and diffuse rays on 

 the other hand, is very striking. This is well illustrated by 

 Fig. 700. On the left is seen a polished segment of the trunk 

 of C. Fraseri (compound and aggregate rays). On the right 

 appears a polished trunk of C. stricta (diffuse rays). Here 

 the rays are at first distinct and later die out. The conspicu- 

 ous stage is aggregate, while that representing the disappearance 



FIG. 68. Tangential section of a large ray in the 

 younger stem of Casuarina Fraseri, showing aggregate 

 condition. 



