252 MOSSES AND FERNS chap. 



The presence of fungous filaments in the roots of the 

 Ophioglossaceae has been repeatedly observed, and has been 

 the subject of recent investigations by Atkinson,^ who is inclined 

 to regard them as of the same nature as the mycorrhiza found 

 in connection with the roots of many Dicotyledons, especially 

 Cupuliferae. Atkinson asserts that he finds them invariably 

 present in all the forms he has examined ; but Holle ^ states 

 that, while they are usually present in Ophioglossum, he has 

 found strong roots entirely free from them, and that in 

 Botrychium rutcEfolium they were mainly confined to the diarch 

 roots, and that this is connected with a weakening of the growth 

 of the root through the growth of the fungus, by which the 

 triarch bundle of the normal fully-developed root is replaced by 

 the diarch form of the weaker one. 



The third genus of the Ophioglossaceae, Hehninthostachys, 

 with the single species H. Zeylanica, is in some respects inter- 

 mediate between the other two, but differs from both in some 

 particulars. The sporophyte, which alone is known, and that 

 very imperfectly, has a creeping fleshy subterranean rhizome, 

 with the insertion of the leaves corresponding to Ophioglossuin 

 pendulum. According to Prantl,^ who has made a somewhat 

 careful study of a plant, the roots do not show any definite 

 relation to the leaves, as Holle claims is the case in the other 

 genera. The plant sends up a single leaf, which may reach a 

 height of 30 to 40 cm, or more, and as in the Ophioglossum 

 vulgatum and B. Virginianum, the sporangiophore arises from 

 the base of the sterile division of the leaf The latter is 

 palmately lobed, and the primary divisions are also divided 

 again. Often the primary divisions are ternately arranged, as 

 in the larger species of Botrychium. The venation is different 

 from that of the other Ophioglossaceae, and is extremely like that 

 oi Angiopteris. Each pinnule is traversed by a strong midrib, 

 from which lateral dichotomously branched veins run to the 

 margin. In regard to the structure of the sheath that encloses 

 the young leaf and stem apex, Hehninthostachys resembles 

 Ophioglossum. 



Prantl ■* states that the vascular cylinder of the stem is solid 

 on the lower surface, but on the upper side has the openings 

 corresponding to the leaf insertions. Two primary bundles 

 are formed for each leaf, which fork before they enter the petiole, 



1 Atkinson (2). ^ Holle (i). » prantl (7). ■* Prantl, I.e. 



