434 



JV. E. Stevens — New Jersey Palmoxylon. 



toxylem groups. In these smaller roots, of course, the central 

 region is much smaller in proportion to the whole stele and 

 contains no internal vessels or large intercellular spaces. 



One of the most interesting sections found was that of the 

 very small root shown in fig. 23. While no phloem elements 

 can be distinguished in this root section, the xylem shows the 

 arrangement of a very young tetrarch root. In this very small 

 root, as in the larger ones, the peri cycle may be readily dis- 

 tinguished. Unfortunately the cortical portion of this root 

 was obscured by a deposit of some foreign substance. 



Phloem. — As noted above, the phloem was preserved in com- 

 paratively few cases. Not more than five of the root sections 



Figs. 21-24. 



Fig. 21. Stele of a smaller root with endodermis, showing pericycle, alter- 

 nate phloem and xylem groups, and a zone of sclerenchyma. x 175. 



Fig. 22. Cortex of same root as that shown in fig. 21, endodermis (E). 

 stone cells (A), outer cortex (O). x 175. 



Fig. 23. Stele of very small root, the xylem of which has the typical 

 tetrarch arrangement, x 175. 



Fig. 24. Phloem group from large root, x 265. 



in 



showed well preserved phloem. Even in the root shown 

 fig. 20, less than half of the phloem groups remained. Fig. 

 24 shows, however, a group which was unusually well pre- 

 served, and this may perhaps be taken as typical. It will be 

 noted that the protophloem consists of small cells with thin 

 walls while the sieve-tubes of the metaphloem are very much 



