346 



BOTANICAL GAZETTE 



[may 



dichotomous. This view of the character of the branching was 

 confirmed for 0. vulgatum by Poirault (ii). 



The occurrence of the two methods of branching within this 

 family has suggested the desirability of further examination of this 

 feature. This investigation has accordingly been undertaken with 

 a view to securing further data bearing upon the relation of the 

 three genera to each other and of the family to other Pteridophytes. 



Ophioglossum 



Poirault (ii) made the first critical examination of the nature 

 of the branching of O. vulgatum. He concluded that the branching 

 is usually only apparent, and that it is due to the development of a 

 stem bud upon a young root before the root has broken through the 



Fig. i. — Transverse sections of a branching rhizome of Ophioglossum vulgatur, 

 only the xylem is shown; X7. 



cortex of the parent rhizome. In a single instance true branching 

 was found, and anatomical examination showed this to be dichot- 

 omy. So far as the writer is aware, there is no record of branched 

 rhizomes in other species of this genus. 



Ophioglossum vulgatum. — In the examination of some 300 speci- 

 mens of this species, five branched rhizomes were found. These 

 were examined in serial sections, and in all cases the original stele 

 has divided into two equal and similar steles (fig. 1). There can 

 be no doubt that this is dichotomy, as contrasted with monopodia! 

 branching. The term "dichotomy" is here used to denote that 

 branching in which a stem divides into two equal stems, as in 

 Lycopodium, and is not meant to imply an exactly equal division 

 of the apical cell of the rhizome. 



Ophioglossum pendulum. — In the examination of some 100 

 rhizomes of this species, two branched specimens were found. As 



