EARLY STEM ANATOMY OF TODEA BARBxARA 



James E. Cribbs 



(with PLATES xxiii-xxvi) 



The work of Jeffrey (6) and Faull (4) on the Osmundaceae, 

 in which they interpreted the stele as containing a medulla of 

 cortical origin, has stimulated an investigation into the condition 

 of the stele as found in the ancestry of the line, and has brought 

 forth a great deal of criticism. 



The present investigation of the early sporophyte stages of 

 Todea barbara was undertaken to ascertain whether in the early 

 periods of organization and development there might be some 

 phases which would be significant as to the ancestral stelar condi- 

 tion. Spores were sown, and from the resultant gametophytes 



■ 



large numbers of sporophytes were secured and examined in all 

 stages of development up to the time of departure of the fourteenth 

 leaf trace. Considerable variation appears in the development of 

 the young sporophyte and in many of its anatomical features. 

 This is especially true of the young plant before it has established 

 its independence of the gametophyte. The first root, for instance, 

 sometimes elongates first, breaking through the old venter wall, 

 but more commonly the leaf takes this initial step. There is 

 irregularity in the phyllotaxy of the first leaves, in the appearance 

 and attachment of the first roots, in the appearance of sclerenchyma, 

 and in the time of medullation. 



The earliest protoxylem to appear has been observed to special- 

 ize opposite the foot attachment, where it continues downward 

 in one of the two protoxylem points of the root, and upward into 

 the stem, where it is associated with the elements which are diverted 

 into the first trace. Part of the protoxylem elements of the second 

 group in the root turn out and enter the foot region, while the 

 others are oblique and are continuous into the basal portion of 

 the stem, or may terminate at the junction of the foot and stem, 



279] 



Botanical Gazette, vol. 70 



