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THE AMERICAN NATURALIST 



[Vol. XLl 



simple forms of B. simplex, are more or less extensively branched. 

 This is especially marked in such large species as B. virginianum 

 and B. lanuginosum. 



The relation of the fertile and sterile periods is essentially the 

 same as in Ophioglossum, and there is the same variation in the 

 point of divergence of the two leaf segments. Thus in O. ohli- 

 ■quum Muhl. the two are separated almost to the base. In 0. vir- 

 ginianum and O. lanuginosum (Fig. 6, B) the spike appears to arise 

 ■close to the lamina of the leaf or even above its base. No material 

 was available for a critical study of this point in B. virginianum, 

 but in 0. lanuginosum Wall, where (see Engler & Prantl, loc. 

 cit., p. 471) it is stated that the spike arises from the base of the 

 sterile segment; even a casual examination will show that this is 

 more apparent than real (see Fig. 6, B). If the leaf be looked at 

 from in front it is very evident that the peduncle can be traced 

 for a long distance below the bases of the sterile leaf segments, 

 although only the anterior face is free, the inner face and sides 

 being completely adherent to the base of the sterile segments. 



Helminthostachys. 



A similar condition to that found in Botrychium lanuginosum 

 prevails in the third genus, Helminthostachys (Fig. 7), a mono- 

 typic genus of the Indo-Malayan region. This is much nearer to 

 Botrychium, in its general morphology, than it is to Ophioglossum, 

 although, in the character of both the prothallium and fertile 

 spike, it is to some extent intermediate in character between the 

 two genera. 



In Helminthostachys the sterile segment, as in most species 

 of Botrychium, is ternately divided, and the anterior margins 

 of the stalks of the two lateral leaf segments are continued as 

 more or less conspicuous wings enclosing the adherent base of 

 the peduncle. 



Distribution of the Vascular Bundles. 



A careful study of distribution of the vascular bundles of the 

 leaf was made in most of the species that were available, to see 



