470 



MOSSES AND FERNS 



CHAP. 



ously, like those of Isoetes. The sporangia are borne singly, in 

 the axils of the sporophylls, which may differ scarcely at all 

 from the ordinary leaves (Z. selago, L. luciduhwi), (Fig. 248), 

 or the sporophylls are different in form and size from the other 

 leaves and form distinct strobili, which are often borne at the 

 end of almost leafless branches (Fig. 243). 



None of the investigated species of Lycopodium show a 

 definite initial cell at the apex of the stem, and Treub ^ was 



B 



Fig. 246. — Longitudinal section of the stem apex oi Lycopodium luciduhcm (Michx.), X 30. sp, Young 

 sporangium ; B, longitudinal section of the young sporangium of the same species, X 215. 



unable to determine positively whether such a one exists in the 

 embryo. In L. phlegmaria ^ he describes and figures embryos, 

 where a single prismatic apical cell is apparently present, but 

 in others the presence of such a cell was doubtful, and in L. 

 cernmivi in no case did he find any evidence of a single initial. 

 The vegetative cone of the mature sporophyte is usually 

 broad (Fig. 246) and only slightly convex. Its centre is 

 occupied by a group of similar initial cells, which in L. selago, 



Treub (2), vol. v. 



2 Treub, I.e. PI. XXIX. 



