20 



PSILOTALES 



[CH. 



chyma succeeded externally by an ill-defined phloem (fig. 119, A, 

 p) surround the xylem and a fairly distinct endodermis (fig. 119, 

 A and B, e) encloses the whole. To Mr Boodle^ is due the 



-px 



Fig. 119. A. Diagram of transverse section of aerial shoot of Psilotum 

 triquetrum. a — c, cortex ; p, phloem ; e, endodermis; s, stereome ; 

 X, xylem ; a, gap in xylem. 



B. Enlarged view of one of the angles of the xylem shown in A. 

 px, protoxylem. 



C. Part of transverse section of an approximately triangular 

 rhizome stele showing a portion of the metaxylem x^ ; px, proto- 

 xylem elements ; x^, secondary xylem. 



1 Boodle (04). 



