Ironside. — Anatomical Structure of N.Z. Piperaceae. 



345 



The structure was carefully examined. Secondary thickening is deve- 

 loped to a marked degree, and is especially noticeable near the base of the 

 stem. The bundles form a ring, each separated by wide medullary rays, 

 which are always densely granular. The medulla is also stored with starch. 



Sections through the base of the stem and the seedling show that the 

 bundles in the root are continuous with those of the stem ; the ring of the 

 stem gradually passes over into that of the root. The centripetal xylem 

 in the root can be traced between the bundles, and sometimes occurs as 



Fir, 12 



G. I I 



Fig 14 



Fig. 15. 



Fig. 11. Hypocotyl, showing endodermis. X 150. M. excelsum. 



Fig. 12. Shows splitting of xylem plate. X 150. M. excelsum. 



Fig. 13. Root, Peperomia : 6 protoxyleins, c ; b, cortex ; a, piliferous layer. 



Fig. 14. Stem, Peperomia, longitudinal : a, annular vessels ; b, secondary xylem ; 

 c, phloem ; d, cortical tissue. X 150. 



Fig. 15. Stele from root, older plant : 8 protoxyleins, c ; 8 phloem masses, b ; a, endo- 

 dermis. Small amount of central medulla. X 150. M. excelsum. 



scattered elements. Scattered elements often occur in the stem, to the 

 sides of the bundle ; so it would seem that there are traces of centripetal 

 xylem in the stem. Again, in the peduncle, where one might expect to 

 find ancestral traces, many of the bundles show small elements to the sides 

 of the bundle. 



Root — Peperomia Endlicheri . 



In P. Endlicheri, on the other hand, we find a small stele in the root, 

 with 6 (sometimes 6 to 8) protoxylems, but with very feebly developed 

 xylem, so that there is no complete centripetal plate. 



