362 BOTANICAL GAZETTE [may 



Discussion. — As stated above, neither axillary nor adventitious 

 buds occur in the rhizomes of either Ophioglossum vulgatum or 0. 

 pendulum; and where branching occurs in these species, it is dichoto- 

 mous. On the other hand, the buds and branching of Helmin- 

 thostachys resemble those of Botryckium in every respect. These 

 facts may be considered further evidence of the close relationship 

 of these two genera ; at the same time, they will serve to emphasize 

 the differences between these two genera on the one hand and 

 Ophioglossum on the other. 



Lang (9) has mentioned the similarity between the vascular 

 connection of the branches of Botryckium and of species of the 

 Hymenophyllaceae. For purposes of comparison, the origin of the 

 axillary buds of a species of Trichomanes from Samoa has been 

 examined. The leaf has an apical cell from the beginning and 

 develops to a considerable extent before the branch appears. The 

 formation of the branch is initiated by the appearance of an apical 

 cell. The exact method of formation of this apical cell of the 

 branch was not determined; but it is evident that it arises late and 

 from the growing point of the leaf. The axillary branches of 

 Trichomanes, therefore, are foliar in origin. In Botryckium, as 

 shown above, the axillary bud is in no way related to the apical 

 cell of the leaf; it arises directly from a portion of a segment of the 

 apical cell of the rhizome; and its position on the base of the leaf 

 is incidental and does not indicate a foliar origin. The similarity 

 between the branching of Botryckium and Trickomanes, therefore, 

 is not close. 



The mature axillary buds of Botryckium are of the simplest pos- 

 sible form, an undifferentiated layer of meristematic cells; and it is 

 to be noted that at no time in their development is there any differ- 

 entiation. This may be accepted as evidence of reduction produced 

 in connection with dormancy ; and we may conclude that Botryck- 

 ium and Hclmintkostackys have been derived from a form which 

 branched freely in a monopodial fashion. This is in full agreement 

 with other evidence which points to a relationship of the Ophio- 

 glossaceae to the primitive forms of Filicales, especially the Zygop- 

 terideae. 



