THE ADULT SPOROPHYTE 



97 



inner side of the wood, so that there is a sHght suggestion, at least, of a concentric 

 structure of the bundle, such as is found in the petioles ofBotrychium. The xylem is 

 composed entirely of tracheids with reticulate markings. The rest of the bundle is 

 made up of sieve tubes, mingled irregularly with smaller, thin-walled elements. It 



could not be certainly deter- 

 mined whether any sieve tubes 

 were developed on the inner 

 side of the wood. 



Thenumber of bundles in 

 the petiole, especially in large 

 specimens, is much greater 

 than in any of the species of 

 Euophtoglossum. In a spe- 

 cimen of medium size (fig. 66) 

 eighteen bundles could be 

 seen, of which probably seven 

 or eight are destined to sup- 

 ply the spike. In the fertile 

 leaves these form a complete 

 circle, but in sterile leaves 

 there are no bundles on the 

 adaxial side of the section. In the free portion of the peduncle, which is relatively 

 slender, the number of bundles is much less than in the broad basal portion. In 

 the smaller specimen figured there were but three bundles in the middle part of the 

 peduncle. The complete absence of the adaxial strands in the petiole of the sterile 

 leaf, even at its base, is a strong confirmation of the view suggested by both the older 

 leaf and the younger stages, that the peduncle is really an independent structure 

 whose bundles are joined directly to the rhizome. 



A B 



Fig. 67. 

 A, longitudinal; B, transverse section of the root apexoi Ophioghssum pendulu 



Fig. 68. 



A. Diarch root-bundle of Ophhglossum pendulum. 



B. Tetrarch root of the same. Xto. Dotted area is mycorrhizal zone. 



O. intermedium (fig. 69) closely resembles 0. pendulum in its anatomy, like the 

 latter developing stomata upon both sides of the leaf, and these stomata are very 

 large and show accessory cells similar to those found about the stomata of 0. 

 pendulum. Except for the difference in size, the arrangement of the vascular bundles 

 in the peduncle and their structure is closely similar to that in 0. pendulum. 



7 



