404 



THE ANATOMY OF WOODY PLANTS 



It will be advantageous at this stage to compare the woody 

 region of the herbaceous stem of Helianthus with the axis of Ca- 

 suarina. Fig. 282^ represents diagrammatically a Casuarina with 

 compound foliar rays. The best developed of the rays are di- 

 rectly related to leaf traces, while the intervening less pronounced 

 ones belong to the foliar strands of another node. In order that 

 the vertical relations of the foliar bundles to storage rays may 



a b 



FIG. 282. Stems of Casuarina and Helianihns. Explanation in the text 



be seen, the bark of the stem is removed on the side facing the 

 reader. The distant aspect still retains its bark as well as its 

 leaf bases, which are represented as pyramidal elevations on the 

 surface. In Fig. 2826 is seen a corresponding diagram of the 

 lower region of a stem in Helianthus. The topographical condi- 

 tions are virtually the same, but for the fact that there are three 

 leaf traces to each leaf in the sunflower, instead of a single one, as 

 in Casuarina. 



In the oak the longitudinal depressions of the woody cylinder 

 do not correspond to rays belonging to a single leaf trace, but 



