60 



THE OPHIOGLOSSALES 



being no trace of procambium inside of the leaf traces in the apical region of the 

 stem itself. Fig. 40 shows a sporophyte which was cut at right angles to the primary 

 root, which in this case had a triarch bundle. Near its base the three xylem masses 

 increase in size and form a nearly complete ring of tracheary tissue, which higher 

 up is continued into the leaf traces. The third leaf has already begun to form, but 

 is still very small. Below it, however, can be clearly seen the beginning of its large 

 leaf trace, which can be followed downward to its junction with the second root, 

 which is now just about ready to emerge. The stele of the second root is con- 

 nected with the central cylinder of the axis near its junction with this third leaf 

 trace. The stem apex occupies a very small area, crowded between the base of the 

 second and third leaves. Its deep, narrow, apical cell is not as conspicuous as is 

 often the case. 



Fig. 41. 



A-F. Six of a series of horizontal sections of a young sporophyte of Botrychium virginianum. X75. 

 B passes through stem apex, jtf, which is shown more enlarged in G; r 2 , second root; / 2 , second leaf. 



A similar sporophyte is shown in cross-section in tig. 41. This was cut in 

 the plane of the Hist root, which makes a sharp angle with the base ol the cotyledon. 

 The thick stele of the root is much expanded where it joins the leaf traces to form 

 the beginning of the tubular stele of the axis, and at the point of junction there is 

 a large nearly solid mass of short, irregularly disposed, reticulate tracheids. This 

 young sporophvtc was evidently the further development of an embryo of the 

 type shown in fig. 35, A . The trace of the cotyledon makes a right angle with the 

 stele of the root and on the side opposite to its junction with the stele of the root 

 there can be seen the trace belonging to the second leaf, which is already will 

 developed. The apical cell is tetrahedral in Botrychium virginianum and the 

 cells are cut off in regular segments from its three lateral faces. Segmentation is 



