*b 



\—a 



Figure i. Diagram of root structure and endodermis. 

 Transverse section showing (a) endodermis and (b) 

 Casparian strip; (c) median longitudinal section; (d) 

 endodermis with continuous Casparian strip round trans- 

 verse and radial longitudinal walls. — Priestley (63) 



