!3° 



BOTANICAL GAZETTE 



[FEBRUARY 



the central axis divide in either of two planes (fig. 13). The first 



em elements 



lem, become differentiated in the cotyledons; there 



are 4 



in 



1 





V>T 



Fig. i. 



Transverse section of a branch showing epidermis, cork cambium, 



> 



cortex with resin ducts, phloem, xylem, pith, and a leaf trace. 



from near 

 tube. Th 



protoxylem 



16-20). 



significant 



in the leat bud (stem 



time there is no xylem present in the primary root 



