44 LANG, Stele of the Shoot of Isoetes lacustris. 





Text -figure 7. 



Diagrams of the relative positions of the tissues of the stele of 

 Isoetes as seen in longitudinal [A) and transverse (B) section. 



On the left-hand side the anomalous meristem and secondary 

 zone are represented, while only the primary components of the stele 

 are shown on the right-hand side. 



«, central region of procambium ; #, radiating rows of meristem 

 around central region, a, central column of primary xylem ; 6 1 , base 

 of xylem of leaf-trace ; />'-', outer xylem ; c, xylem sheath ; d, primary 

 phloem ; e, secondary prismatic tissue ; /J meristem g, cortical tissue. 



