146 PHARMACEUTICAL BOTANY 
y 
: 
: 
/ 
/ 
| 
: 
] 
] 
/ 
] 
: 
' 
ee ee 
CG 
Yf ry) 
Fic. 84. Diagrams illustrating leaf traces, branch traces and gaps. A, longi- 
tudinal section of node through leaf trace and gap. __B, similar to A, but with branch 
trace and gap also present. C, view of vascular cylinder showing departure of leaf 
and branch traces, and the gaps associated with each. D, E, F, cross sections of 
stem illustrated in A at levels a-a, 6-b, and c-c, respectively. G, face view of outside of 
cylinder shown in C, the leaf and branch traces cut away at the surface of the cylin- 
der. H, transverse section of G at a-a. (In diagrams A-H the vascular tissue is not 
differentiated as xylem and phloem; the traces are doubly cross-hatched. In /, 
more detailed structure is shown, protoxylem, metaxylem (secondary xylem) and 
pith being indicated. (From “An Introduction to Plant Anatomy” by Eames and Mac 
Daniels, McGraw-Hill Book Co., Inc., publishers.) 
