230 



MOSSES AND FERNS 



CHAP. 



smaller species. Prantl ^ describes it as follows for O. Lusitani- 

 cuin, and states that it is essentially the same in other species. 

 " The primary bundle given off from the stem branches just after 



it enters the petiole. The 



'L 



> 



;J /, 



m 



main bundle gives off 

 two smaller lateral 

 branches right and left. 

 The latter branch again 

 near the base of the spor- 

 angiophore, and the upper 

 branches from each unite 

 to form the single bundle 

 that enters the latter." 



The sporangia are 

 large cavities sunk in the 

 tissue of the sporophyll, 

 and scarcely projecting 

 at all above the surface, 

 where the position of each 

 one is indicated by a 

 faint transverse furrow 

 which marks the place 

 where it opens. Seen in 

 sections parallel to the flat 

 surface these appear per- 

 fectly round, but in trans- 

 verse section are kidney- 

 shaped (Fig. 12 1, C). 



The apex of the stem 

 forms a blunt cone, which, 

 however, is not visible 

 from the outside. A 

 longitudinal section 

 through the end of the 

 stem shows that it is 

 covered by a sheath com- 

 posed of several layers of 

 cells, and this encloses a 

 cavity in which are the growing point of the stem and the 

 youngest leaf. The leaves here form much more rapidly than 



• 1 Prantl (7), p. 155- 



Fig. 113. — Ophioglosstim vulgaUim iX'-)': ^i- 



