238 BOTANICAL GAZETTE [march 



on the upper right by a relatively small leaf gap beside an out- 

 going leaf trace. The wood is entirely primary, with groups of 

 parenchyma scattered throughout it. The mesarch structure of 

 the bundles is not evident here, but may be demonstrated by 

 means of longitudinal sections. The large-celled, winding endo- 

 dermis is, unfortunately, too faintly stained to show clearly in the 

 figure. According to Farmer and Freeman (4), there is in this 

 form cork formation confined to the upper surface and originating 

 at the bases of the cast-off leaves. 



The most extraordinary member of the group in regard to its 

 wood structure, however, is undoubtedly Botrychium. In this 

 form there occurs a well developed cylinder of secondary 

 wood, as well as a definite cork layer. The stem shown in trans- 

 verse section (fig. 3) illustrates this. The woody cylinder sur- 

 rounding a rather large starchy pith is solid with the exception of 

 small leaf gaps, one of which appears in the lower part of the figure 

 to the left of a horizontal root. The wood, which is 



com 



numerous 



ma 



primary 



The peri- 



ma 



by an endodermis, frequently multiple. A rather large cortex, 

 also utilized in the storage of starch, is bounded by cork which is 

 visible in the upper right-hand corner of the figure. 



The roots of the three genera show no secondary wood of any 

 account. Boodle (2) has described the addition of a few tracheids 

 at the base of the old roots of Ophioglossum vulgatum and Bo- 

 trychium Lunaria, but the later formed parts show only typically 

 primary bundles, in the case of the former genus monarch in 

 structure, and in the latter triarch or tetrarch (figs. 4, 5). The 

 hexarch stele of the Helminthos tacky s root also shows only primary 



arrangement (fig. 6). 



elements themseh 



jra differs almost as much as their arrangement. Fig. 7 shows 

 elements in the metaxylem of the root of O. vulgatum, stained 

 i Haidenhain's iron-haematoxylin and safranin. They do not 



from those of the stem 



neral 



