240 



Plants and their Ways in South Africa 



The Cycadacea; come of a very ancient lineage, for their 

 fossil forms are found in older rock formations than those of 

 any of their living Gymnosperm relatives. 



A xerophytic character of these plants is the well-developed 

 underground stem systeni by which vegetative reproduction 



Fig. 214. — Siangcria zeyhcri. Showing the feathered venation. 



is secured. A curi(7us feature is shown in Fig. 213. From 

 the upper [xjrtion of the tap root, roots are given off wliich 

 grow directly upward (apogeofropic). Tliese contain within 

 their cortex small blue-green algte which may assist in the re- 

 spiration of the roots. 



I'iie cones of E. J'Videriii Guilitimi, Lehm., wliicli grows 



