110 



THE OPHIOGLOSSALES 



sterile lamina. In the larger species, like B. virginianum, many hundred sporangia 

 may be developed upon a single sporangiophore. In these larger and more special- 

 ized forms the sporangium is usually smaller and is better differentiated, always 

 having a more or less distinct pedicel. 



The form of the sporangiophore in Helminthostachys is to some extent inter- 

 mediate between that of Ophioglossum and Botrychium, but on the whole comes 

 nearer to Botrychium. The sporangia are densely crowded along the Hanks of the 

 spike, thus forming two rows somewhat as in Ophioglossum, hut they are very much 

 more crowded and an formed in groups oi synangia which project free above the 

 surface (it tin voting spike. The sporangia do not arise singly, hut are borne upon 

 short branches or secondary sporangiophores which suggest the lateral branches of 

 the sporangiophore in Botrychium, hut are far less regularly disposed. By the fur- 

 ther growth of the sporangia the axis of the spike is entirely concealed and a casual 

 examination would indicate that the sporangia were formed equally at all points of 

 its surface, but a study of the development shows that they are lateral in structure. 

 as they are in Ophioglossum. 



THE 0K\ ELOPMENT OF THE SPORANGIOPHORE. 



The sporangiophore in both Ophioglossum and Botrychium becomes visible at 

 a very early period. In Ophioglossum moluccanum I have found that the spor- 

 angiophore can be recognized even earlier than Bower has stated for 0. vulgatum 

 and 0. reticulatum. A median section of a ver) voung fertile leaf in (). moluccanum 

 is shown in fig. 56, D. The apex of the leaf has scarcely become free and the apex, 



as well as nearly the whole of the 

 ad axial surface, is made up of 

 large columnar meristem cells, of 

 which it is difficult to say that 

 any one is the single apical cell 

 of the leaf. The leaf trace is al- 

 ready evident, passing into the 

 base of the young leaf, which is 

 strongly inclined forward so that 

 flu- real apex of the leaf is not 

 directed vertically upward, bur is 

 on the adaxial side of the leaf 

 rudiment. Hie apex of the young 

 sporangiophore arises from the 

 tissue immediately below the apex 

 of the sterile segment, and the 

 whole of the adaxial portion of 

 the hat below the apex of the 

 voung sporangiophore may be said 

 to belong to the latter ami not 

 to the sterile portion of the- leaf. 

 There is thus practically a dichot- 

 omy of the apex of the young 



Fig. 81 ■ 



A. Longitudinal section *»l young sporophyll ot Ophioglossum moluccanum, 



still inclosed in the stipulai sheath, sh X50. 



B. Apex of .sterile lamina. sf>, sporangiophore. 



C. Apex of sporangiophore. X1Z5. 



I). Transverse section 01 a verv young sporophyll, showing dichotomy ol 

 apex. ■ IJJ, 



sporophyll, and the two branches (viz, the sterile segment and the sporangiophore) 

 are structures of equal rank. It would thus appear that the old view put forward 

 by Mettenius of two equal branches of the fertile leaf is probably the correct one. 

 It is probable that younger stages than those figured by Bower for 0. vulgatum and 

 0. reticulatum would show the same condition of affairs that we pointed out in 



