396 



THE ANATOMY OF WOODY PLANTS 



just below the next superior node. In the latter the foliar traces, 

 seven in number, are clearly subtended by a greater or less depth 

 of storage parenchyma, precisely as is the case in the oak. In b 

 the foliar trace is shown in its radial and tangential aspects. In 

 the radial view the trace is confronted in its upper region by 

 storage parenchyma (black), while below it is subtended by ordi- 

 nary wood. Above the trace lies the storage tissue of the leaf gap. 

 In the tangential figure the trace appears as a light spot in a mass 



a o c a 



FIG. 273. Diagram of decorticated stems of Leea and Vilis in three dimensions. 

 Explanation in the text. 



of darkly rendered storage parenchyma. The latter, farther down, 

 is divided into two by a median mass of unmodified wood. In c 

 is shown a view of a slender stem. In this instance, for variety, 

 the opposite or tendril side of the stem is exposed to observation. 

 On account of the shallow diameter of the woody cylinder the 

 trace is of a radial dimension so great that it equals that of the 

 cylinder from which it is derived. As a consequence there is no 

 parenchyma facing the leaf trace, and storage tissue is entirely 

 flanking in its distribution. This is a natural and necessary 

 geometrical result of the thinning of the cylinder of wood in the 

 more slender axes of the vine type. In d are shown the radial 

 and tangential relations of the foliar traces and the adjacent storage 



