1914] 



HILL— ANATOMY OF LY CO PODIUM 



75 



L. Billardieri 



The organization of the strobilus in this species is distinctly 

 radial, and this condition was constant in all the material examined 

 (fig. 18). The further development of the metaxylem also results 

 in a very regular structure for the stem. This structure consists 

 of several radiating bands of xylem with phloem groups between 

 them. The xylem also has a great tendency to form an almost 



Fig. 19. — L. Billardieri: transverse section of a mature stem, showing the inner 

 xylem ring; p x , protoxylem; p, phloem; X185. 



complete ring inside the stele. The center of this ring may be 

 occupied by a single isolated strand of either phloem or xylem. 

 The development of the ring is dependent entirely upon the behavior 

 of the metaxylem and not upon the peripheral growth as in L. 

 carinatum. for it is not peripheral to the stele, but is located inside 

 the periphery, forming an inner ring with radiating masses of xylem 



which extend to the circumference of the vascular cylinder (Jig. 19). 



