596 



A TEXTBOOK OF THEORETICAL BOTANY 



though it is not a branch as in Selaginella, but is the lower end of the main 

 stem, taking the place of the short-lived primary root of the embryo plant. 



V 



.<* 



-A 



W' 



Leaf trace 



Stele 



Rhizophore stele 



Root 



Old root 



■%% 



Fig. 605. — Isoetes lacustris. Longitudinal section of 

 the entire stem in the plane of the grooves showing 

 the curved rhizophore stele giving off root traces. 



Rhizophore stele 





Ij Rhizophore stele with 

 root traces 



Fig. 606. — Isoetes lacustris. Transverse 

 section through the lower pirt of the 

 stem showing the ends of the curv'ed 

 rhizophore stele on each side of the 

 main stele. 



