94 



THE OPHIOGLOSSALES 



cell and its segmentation as clearly as in the younger roots; however, only a small 

 number of these later roots were sectioned and it may be that they were not all 

 quite normal. 



A section of an adult root is shown in fig. 59,5. The cortical region is made up 

 of simple parenchyma and the mycorrhizal zone is very conspicuous. The endo- 

 dermis is not very clearly defined, less so than in the earlier roots, and its limits are 



Fig. 6i. 

 Five sections of a full-grown sporophyll of Ophioghssum moluccanum, E, section of peduncle of spike; /, lacunae. 



not easily determined. The cortical cells inside the mycorrhizal zone are densely 

 filled with starch. More than half of the section of the bundle is occupied by the 

 large solid mass of wood. This is separated from the endodermis by a single layer 

 of pericycle cells. The single mass of phloem lying next the wood is not much more 

 than half as large. 



AN.ATOMY OF OPHIODERMA. 



Owing to the dorsiventral position of the rhizome and to the more rapid de- 

 velopment of the leaves, the section of the stem apex in Ophioglossum pendulum 

 differs a good deal from a similar section oi Euophtoglossum (fig. 64). The base of 

 the leaf is bent sharply upward, this being the case also in the very young leaf which 

 is inclosed within the bud. The leaves break through 

 the inclosing sheath in a very rudimentary condition, 

 although of such size that a section through the base 

 of the youngest visible leaf shows usually but a single 

 younger leaf inside the sheath, instead of the three or 

 four that are seen in a similar section of the bud in 

 Euophioglossum. Within the sheath at the base of the 

 youngest visible leaf there is found a cavity in which is 

 the growing point of the stem and the youngest leaf. 

 The apex of the stem forms a strongly inclined, nearly 

 plane surface and, as in Euophioglossum, the growth is 

 from a single apical cell which, so far as could be deter- 

 mined, has the form of a three-sided pyramid, whose 

 lateral faces are more or less strongly convex and whose apex may be truncate. 

 From the few cases observed it is not possible to say definitely whether basal seg- 

 ments are regularly cut off as well as the lateral ones. The segments cut off from 

 the lateral faces are large and the divisions irregular. 



Owing to the large size of the sporophyte there are practical difliiculties con- 

 nected with the study of the vascular system of the rhizome from a series of micro- 

 tome sections. The numerous bundles in the leaf base do not unite into a single 



Fig. 62. 



Apex of root of Ophioglossum nioluc- 

 caf7wm, showing dichotomy. X150. 



