I02 



MORPHOLOGY OF GYMNOSPERMS 



Mekn /? doreTy iel 



Fig. 78. — Ceratozamia mexicana: transverse section of hypocotyl slightly below 

 exit of cotyledonary traces; the diagram shows the position of the stele, surrounded 

 by three large groups of extrafascicular cambium (a, 6, s), and some smaller groups 

 like e and r; the drawing shows a portion of the section indicated in the diagram, 

 including one of the groups of extrafascicular cambium (a), parts of 6 and s, and also 

 the smaller groups (e and ;-) ; the bundles of the stele are mesarch, with considerable 

 centripetal xylem. — After Sister Helen Angela (66). 



