i 9 i 5 ] PETRY—OPHIOCLOSSACEAE 347 



in 0. vulgaliim, the branching is dichotomous, and the two branches 

 in each case showed an almost exact equality. 



In the examination of the material of these two species of Opliio- 

 glossum, careful search was made for evidence of axillary buds, such 

 as have been described for Helminthostachys by Gwynne-Vaughan 

 (5), and for Botrychium Lunaria by Lang (9). No such structures 

 have been found in any case; neither is there any evidence of 

 adventitious budding except upon roots. From this it may be con- 

 cluded that the true branching of these species is always dichoto- 

 mous. 



Helminthostachys 



Lang (8) has briefly described the anatomy of two branching 

 rhizomes of this genus. In both, the branches are definitely 

 axillary in position, and it is certain that they have developed from 

 the vestigial buds described by Gywnne-Vaughan (5). In each 

 case, the vascular supply of the branch comes from a mass of 

 accessory xylem which develops outside the usual xylem of the 

 stele, either locally at the base of the branch, or surrounding the 

 stele. There is no connection between the branch stele and the 

 subtending leaf trace. 1 



Material of Helminthostachys has not been available during the 

 progress of this investigation. 



Botrychium 



THE OCCURRENCE OF AXILLARY BUDS 



All the investigation of branching and of the occurrence of buds 

 has been confined to examination of B. Lunaria. On this account, 

 it has seemed advisable to examine other species of this genus with 

 regard to these points. Rhizomes of five species have been secured 

 with branching specimens representing four of these species. 



The genus Botrychium, as organized by Prantl (12), consists 

 of two sections: Eubotrychium, with five species; and Phyllo- 

 trichium, with eleven species. The latter section is divided into 



1 The full description of this material has just been published (Lang, Wm. H., 

 Studies in the morphology and anatomy of the Ophioglossaceae. III. On the anatomy 

 and branching of the rhizome of Helminthostachys zeylanica. Ann. Botany 29:1-54. 

 pis. 1-3. figs. i-S. 1915). In this paper Lang concludes that although no regular 

 cambium is present, "the development of this accessory xylem should rightly come 

 under the conception of secondary thickening." 



