194 



THE ANATOMY OF WOODY PLANTS 



character of the bundles in the group is an indication of affinity 

 with the pteridophytes, but this view seems to have little value 

 when it is realized that the earlier vascular cryptogams usually 



FIG. 143. Bundle of Smilax herbacea 



possessed well-marked secondary growth. Toward the periphery 

 of the stem in each fibrovascular strand lies the phloem, composed 

 mostly of sieve tubes and their companion cells. The small 

 elements of the phloem lying on the very outside and close to the 

 bundle sheath represent the protophloem and are often in a some- 



