THE ADULT SPOROPHYTE 



111 



0. moluccanum and 0. pendulum, and the conclusion that the young sporangiophore 

 IS an outgrowth of the sterile part of the leaf is the result of the subsequent rapid 

 growth of the upper sterile portion of the leaf, which thus carries its apex far beyond 

 the apex of the young spike. 



The young sporophyll in O. pendulum (fig. 64, E) resembles that of O. moluc- 

 canum, except that all the parts are much larger. The apex of the young sporangio- 

 phore appears upon the adaxial side of the very broadly conical young sporophyll. 



Bruchmann's studies on Botrychium lunaria indicate that in this species the 

 separation of the fertile and sterile segments of the sporophyll is the result of a 

 dichotomy of the apex of the sporophyll at a very early stage in its development. 



Fig. 82. 



A. Young sporophyll of Ophioglossum pendulum, sp, the sporangiophore. X2. 



B. An older sporophyll. Xi. 



C. A still older stage, showing venation of lamina. 



D. Base of a full-grown sporangiophore. 



E. Sporophyll with rudimentary lamina, /. 



The sporophyll, however, is larger at this time than is the case in Ophioglossum 

 moluccanum (Bruchmann 2, fig. 57). 



The earliest stages in the development of the sporangiophore have not been 

 studied in Helminthostachys. Bower says (Bower 9, page 455) : 



"The origin of it is similiar (i. e., to Ophioglossum) and its early stages not 

 unlike. It appears at first as an outgrowth on the adaxial side of the sterile 

 frond, and it is curved over while young so that the actual apex is pointed 

 downward." 



In the latter respect it might very well be compared to the strongly bent-over 

 sporangiophore of Botrychium vtrginianum- 



