5H 



A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 510. — HymenophyUum tunbridgetise. Transverse 

 section of rhizome showing protostele with central 

 protoxylem and thick-walled cortex. 



Fig. 511. — HymenophyUum tunbridgetise. Trans- 

 verse section of the petiole showing heavily 

 thickened cortex and collateral stele. 



