GENERAL MORPHOLOGY 443 
not an uncommon thing for sporangia to appear upon the sterile leaf: an 
example of this is shown for B. simplex in Fig. 240M, but it is more 
clearly shown in specimens of B. Zunaria (Fig. 242). Moreover, not a 
part only, but even the whole of the normally sterile lamina may be thus 
occupied, and Goebel quotes a locality on the Ostsee where this condition 
has become constant.1_ The importance of this from a theoretical point 
of view will be discussed later. 
Fic. 242. 
Botrychium Lunaria. Sterile laminae, which occasionally produce sporangia (sf) on 
certain pinnae, and have partly or wholly assumed the form of the fertile spike; fin 
B and C is the fertile spike itself. Natural size. (After Goebel.) 
The third genus, Helminthostachys, differs from the others in having a 
creeping rhizome, which is markedly dorsiventral, bearing the leaves in two 
rows on its upper surface, while the roots spring from its flanks and under 
surface (Fig. 243). The individual roots are not definitely related to the 
leaves either in number or position, a condition comparable with 
Botrychium rather than with Ophioglossum: they branch monopodially, and 
are hairless. The rhizome is normally unbranched? and perennial, serving 
1Schenk’s Handbuch, vol. iii., p- 112. 
2 Farmer (Ann. of Bot., xiii., p. 423) found that adventitious branches were frequently 
seen on old, almost decorticated parts of the rhizome of Helminthostachys. Gwynne- 
Vaughan (Aun. of Bot., xvi., p. 170) has described how in ‘the axil of each leaf, and 
even of the leaves of young seedlings, a narrow oblique invaginated channel leads 
through the cortex to a point just outside the stele, at the upper limit of the leaf-gap. 
A mass of parenchyma, covered in except at its apex by an extension of the endodermis, 
and terminated by a small, obliquely truncated, conical projection extends outwards from 
the stele to meet this invaginated channel. He suggested that ‘these structures represent 
vestigial axillary buds, and that possibly the ancestors of Melminthostachys branched 
more copiously than the present plant. Gwynne- Vaughan’s recognition of their bud- 
character received its full justification by the discovery of similar bodies in Botrychium 
Lunaria by Bruchmann (Flora, 1906, p. 226), which actually develop into lateral 
branches. He found them present chiefly upon young plants, and traced their origin 
each from a single superficial cell of the rhizome: they occur especially where the axis 
