THE ADULT SPOROPHVTE 107 



respect may better be compared to the stomata of Dancea, one of the Marattia- 

 ceae, which shows a similar concentric arrangement of the accessory cells. A 

 cross-section of the leaf shows that the mesophvll is better differentiated than in 

 Botrychium. There is a single compact layer of palisade cells below the epidermis, 

 and below these the mesophyll has very large intercellular spaces which communicate 

 with the stomata. In the anatomy of the leaf, therefore, as well as in its venation, 

 Helminthostachys more nearly resembles the Marattiaceze than it does the other 

 Ophioglossaceae. The section of the petiole is not unlike that of Ophioglossum 

 pendulum (figure 78, D). A section made near the base of the petiole is almost 

 circular in outline and there is a ring of separate bundles. On the adaxial side, 

 however, two other bundles are seen inside the outer circle. Farmer and Freeman 

 (Farmer 2) state that the number of bundles is about seven or eight, but the 

 larger specimens which I have examined show a greater number. If a section of 

 the petiole is examined higher up it no longer appears circular, but is slightly 

 lobed, these lobes corresponding to the bases of the three divisions of the sterile 

 lamina, and on the adaxial side may be seen a fourth lobe which marks the position 

 of the peduncle of the sporangiophore. In this upper region of the petiole the 

 bundles become more or less coalescent, but two adaxial bundles remain quite 

 distinct and are continued upward into the spike. The structure of the bundles is 

 concentric and the general appearance of the section is quite similar to that found 

 in the larger species of Botrychium. 



The anatomy of the stem in the older sporophyte does not differ in any partic- 

 ular, except in the greater size of its parts, from that of the sporophytes already 

 described. The vascular cylinder forms a hollow tube with narrow leaf gaps above, 

 but quite solid on its ventral face. Farmer states that there is both an outer and an 

 inner endodermis and that wood is formed inside of the protoxylem, so that the 

 bundle is mesarch. 



Reference has already been made to the invaginated canals communicating with 

 the stipular cavities and first described by Gwynne-Vaughn (Gwynne-Vaughn 1). 

 In connection with these he describes slight projections of tissue from the vascular 

 cylinder, which are surrounded by the endodermis. These projections he thinks 

 may perhaps be the vestiges of buds which formed at the axils of the leaves and 

 never developed. Whether this explanation is the correct one or not there is no 

 means of determining. Farmer found in the older plants that the roots were prevail- 

 ingly hexarch, ranging from pentarch to heptarch, and that tetrarch roots were rare. 



The endodermis in the bundles of the later roots is much less distinct than it is 

 in the primary root, where it is very easily demonstrated. Within the endodermis 

 is a layer of pericycle cells, separating the endodermis from the radially arranged 

 masses of xylem and phloem. Farmer states that the apical cell of the root appears 

 triangular in section (presumably in longitudinal section), but that it is very often 

 destroyed and as a result of the proliferation of the adjacent tissue an area of cells 

 results recalling the condition obtaining in the Marattiaceae. He also remarks that 

 most of the roots that he examined showed this abnormal condition. 



I made sections of a number of roots taken from young sporophytes where the 

 root tips appeared to be quite normal. I he result was rather interesting. In the 

 early roots there was usually present a tetrahedral apical cell, very much like that 

 of Botrychium and showing a pretty regular segmentation (fig. 80, ('.). I he seg- 

 ments cut off from tin apical cell are large, and even in the early roots it is prettj 

 certain that the root cap owes its origin, in part at least, to tin- outer cells of the lateral 

 segments. Cross-sections of the apical cell show the same triangular form as longi- 

 tudinal sections and the divisions in tin segments of the apical cell seem to be very 



