206 Transactions of the Royal Society of South Africa. 
The epidermal cells of the root are somewhat papillate and, as age 
advances, the outer walls may become markedly thickened. This thicken- 
Fig. 15. 
ing of the walls may extend to the outer cortex, or (fig. 15) the epidermis 
and cell layer immediately next to it may remain comparatively thin while 
a zone of the middle cortex is strongly thickened. Chlorophyll is present 
Fig. 16. 
in the cortex of the aerial region of the young root (fig. 16). It is worthy 
of note that in all essential features this aerial part of the root is similar 
in structure to the subterranean part. 
An interesting feature of the root of S. pumila which does not appear 
to have been recorded for any other species of the genus is the presence of 
