252 BOTANICAL GAZETTE [Marcu 
segment in relation to it may conveniently be designated as the leaf 
trace segment. Fig. 3 shows the same situation in longitudinal 
tangential aspect. Here the trace appears high up in the center of 
the figure and is obviously surrounded on all sides by paren- 
chymatous tissue. This section was made near the region of the 
cortex, so that it represents the leaf strand after it has become 
horizontally inclined. Fig. 4 is a radial view of the same situation, 
illustrating in a similar manner the imbedding of the leaf trace in 
storage tissue in its course through the woody cylinder. This 
section also demonstrates the fact that vessels and fibers again 
make their appearance in the cylinder directly above the leaf trace 
segment after the foliar strand has passed into the cortex. 
It is clear from the foregoing illustrations that the woody 
cylinder opposite the leaf trace undergoes certain modifications in 
relation to the activity of the foliar organ. The strand as it passes 
upward and outward through the cylinder is flanked on either hand 
by storage tissue which may be designated as flanking parenchyma. 
Farther in its outward course, and more marked where the cylinder 
is thick, subtending the trace externally is a mass of tissue which 
may appropriately be called subtending or confronting parenchyma. 
Above the trace is the parenchymatous interval known as the 
leaf gap. It is noteworthy in this connection that the leaf trace 
in the thick or woody cylinder (and all the axes here figured are 
aerial) of S. canadensis has the same topographical relation to 
storage devices as is found in arboreal types like Quercus, Casuarina, 
etc. The origin and topographical relations of the broad ray in the 
oak have clearly and convincingly been elucidated by Eames,” and 
the conclusions reached by this author have been shown by BAILEY’ 
to hold with equal validity for the Betulaceae and Fagaceae in 
general. Eames‘ has also shown that the woody type in. the 
Rosaceae is subject to the same general modifications in relation 
to the leaf trace as obtained in the Betulaceae, Fagaceae, and also, 
? Eames, A, J., On the origin of the broad ray in Quercus. Bot. GAz. 49:161~-167- 
Id. 
3 Baitey, I. W., Relation of leaf-trace to compound rays in lower dicotyledons. 
Ann. Botany 25: 225-241. pls. 15-17. fig. I. 1911. 
4 Eames, A. J., Herbaceous type in angiosperms. Ann. Botany 25§:215-224- 
pl. 14. 191. 
