104 THE OPHIOGLOSSALES 



In fig. 73, A, is shown the terminal bud of a strong plant of B. virginianum. 

 The base of the oldest leaf is cut away so as to show the young leaf for the next 

 year, which is seen to be strongly bent over, and the young leaf segments are rolled 

 inward in a way that very strongly reminds one of the young leaves of the typical 

 ferns. The young leaf is covered with hairs. The roots are thick and fleshy, prob- 

 ably one corresponding to each leaf, although this is not always easy to determine. 

 They are much contracted at the point of insertion. The roots branch freely, the 

 branching being monopodial, thus resembling Ophioglossum pendulum. An exam- 

 ination of the section of the bud shown in fig. 73 shows that the young leaf, which 

 is to unfold the next year, is already well advanced and the formation of the young 

 sporangia has just begun. The sporangiophore is also evident upon the leaf for the 

 following year, and the leaf which is to unfold in the third year can be recognized, 

 but its parts are not yet differentiated. 



While the roots branch freely in B. virginianum, this is much less marked in 

 B. lunaria. In large plants of B. lanuginosum which were examined somewhat 

 carefully it was found that the roots appeared to be quite unbranched, although 

 equaling those of B. virginianum in diameter and showing, like them, a similar 

 tetrarch structure of the vascular cylinder. A more careful examination showed, 

 however, a few very short branches on some of the roots, but these were rare. It 

 may be that the rudiments of these lateral roots are formed, but that they do not 

 develop, and in this respect there is a certain resemblance to the condition which 

 obtains in Helminthostachys. 



The anatomy of the roots does not differ from that of the younger sporpphj^e 

 already described, except that in the larger specimens the roots are regularly tetrarch, 

 while in Euhotrychium they are permanently diarch. 



The earlier roots, as in Ophioglossum, have a tetrahedral apical cell which shows 

 a more regular segmentation than is found in the later roots and in these earlier 

 roots, at least in B. virginianum, there seems little question that the tissue of the 

 root cap is derived entirely from the outer segments of the apical cell. In the larger 

 roots, taken from the older sporophyte, this regularity is not so marked and it is 

 probable, although this could not be determined absolutely, that the lateral seg- 

 ments of the apical cell may also contribute to the tissues of the root cap. The 

 regularity of the segmentation is still less marked in the later roots of B. ohliquum. 

 A slight development of periderm may be seen in the older roots, but this does not 

 form a continuous layer, being developed only in irregular patches. The secondary 

 increase in diameter of the roots is apparently due almost entirely to simple enlarge- 

 ment of the cortical cells. 



THE SPOROPHYTE OF HELMINTHOSTACHYS. 



While Helminthostachys differs very much in habit from the other Ophio- 

 glossaceae, it nevertheless shows that it is unmistakably related to them and especially 

 to Botrychtum. The dorsiventral prostrate rhizome with the ample palmately 

 divided leaves give it a very individual aspect, but, as is shown from a study of the 

 early history of the sporophyte and the gametophyte, there is no question that it 

 should be associated with the Ophioglossaceae. As yet but a single species is gener- 

 ally recognized, which grows throughout the Indo-Malayan region, extending from 

 the Himalayas through the Malay archipelago to northern Australia (plate 8). 



The anatomical details of the adult plant have been very thoroughly investigated 

 by Farmer and Freeman (Farmer 2), and from a comparison of the structure of the 

 adult sporophyte with that of the younger stages it is clear that the essential 



