Betts. — Avtecology of Plants of Peridotite Belt, Nelson. 241 



The spongy 1 issue consists of large thin- walled roundish cells which 

 contain only a few very small chloroplasts, and which form a water-storage 

 tissue. 



The vascular bundles are small, and each is surrounded by a sheath of 

 small parenchymatous cells. There are very few vessels in the xylem, and 

 these are of small diameter. 



Fig. 11. — Notothlaspi australe. Transverse section of leaf ( x 100). 

 Fig. 12. — Notothlaspi australe. Upper epidermis of leaf ( x 100). 



Stem (figs. 13-15). — The epidermis is composed of large cells, which 

 have thin lateral and internal walls, but the external walls are slightly 

 thickened. There is a thin cuticle. Some of the epidermal cells are con- 

 siderably larger, and form special water-storage cells. 



Beneath the epidermis there is a single layer of rounded cells, which 

 contain numerous chloroplasts. The remainder of the cortex, which is a 

 very wide zone, consists of very large round cells with thin cell-walls. All 

 the cortical cells except the outermost layer form an aqueous tissue. The 

 intercellular air-spaces are small. 



The phloem and the xylem form continuous cylinders. The amount 

 of lignified tissue in the xylem is small, and there is a moderately large 

 amount of parenchyma in both the xylem and the phloem. 



The pith is solid, and consists of large rounded thin-walled cells, which 

 form an aqueous tissue. 



