22 



T O R R E Y A 



out, no differentiation of this cauline tissue into metaxylem and metaphloem is 

 seen to occur until after differentiation in the leaf traces themselves has 

 become well established, and then only centripetally from the protoxylem and 

 protophloem (Fig. 8). It is interesting to recall that such a blocking out 

 of the metaxylem and metaphloem pattern, before differentiation occurs, is 

 reported commonly in Angiospermous roots. (Esau, 1940; Williams, 1940.) 





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Fig. 8. Tranverse section of aerial stem of L. sabinaefoUuin, 2710m from apex, 

 showing pattern of the radially organized stele already blocked out, but dififerentiation 

 only present in the peripheral strands of protoxylem and protophloem (X260). 



In the remaining part of the genus Lycopodimn, as represented by the 

 seven species studied,* the apex is not flat, but conical, with laterally borne 

 leaves (Fig. 7). Here, however, the developmental story is generally the 

 same (Fig. 8). So is it true for the numerous species of Sclaginella now in 

 process of investigation ; the detailed study is not yet complete. Before leaving 



* This study includes Lycopodium inundatum L., L. cernitin L., L. atinofinutn L.. 

 L. clavatum L., L. obscurum L., L. sabinaefoUuin Willd., L. compJanatum L., and its 

 variety flabelUfonne Fernald. 



