84 THE OPHIOGLOSSALES 



rudimentary condition of the cotyledon and in the venation of the first foliage leaf, 

 which, although it has a ternate lamina, is quite rudimentary. We have already 

 referred, however, to the rudimentary leaves of B. lunaria, which also sometimes 

 develop a very small ternate lamina. The venation of the first leaf in Hclminthos- 

 tachys also approaches the cyclopterid type found in the leaves of 5. lunaria. The 

 structure of the stele in the young stem also, after attaining the tubular form, is 

 more like that of 5. lunaria than like that of 5. virginianum. 



On comparing the early stages of development of the Ophioglossaceae and 

 Marattiaceae we shall find that they have a good many points in common, which 

 will be discussed more at length after we have described the structures of the latter. 

 Ophioglossum, as to the formation of the cotyledon, is very much like Kaulfussta, 

 while Helmtnthostachys is more suggestive of Dancea. The stipular structures of 

 the two families are unquestionably homologous and the entire conical stipular 

 sheath, found in the lower members of the Ophioglossaceae, is probably an older 

 type than the free stipules found in Botrjchium virginianum and the Marattiaceae. 



In both the Ophioglossaceae and Marattiaceae the young sporophyte at first is 

 made up almost entirely of leaf and root, and the whole vascular system is composed 

 of the leaf traces with no proper cauhne vascular tissues, so that one might almost 

 say that the stem is made up entirely of the bases of the leaves, the dominance 

 of the leaf being the most noteworthy feature in the morphology of these plants. 

 On the whole, probably Helminthostachys most nearly resembles the Marattiaceae. 

 This is true both of the character of the venation of the leaves, the structure of the 

 root bundles, and the development of tannin cells in the young sporophyte. These 

 tannin cells seem to be quite absent from the tissues of both Ophioglossum and 

 Botrychium. 



