I02 



MORPHOLOGY OF GYMNOSPERMS 



}telen (^ Borety 6el 



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, h, s), and some smaller groups 

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

 including one of the groups of extrafascicular cambium {a), parts of b and s, and also 

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

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



