Bower . — Studies in the Phytogeny of the Fi tic ales. 381 
sterile with broad pinnae, or the pinnae of one side of the leaf may be fertile 
and those of the other sterile, or the pinnae themselves may be sterile at the 
base and fertile at the tip. There is perhaps no species that is so variable 
in this respect as B. capense. But, in addition, types are sometimes found 
in which the pinna appears as in B. brasiliense, with the linear sori close 
right and left of the midrib, and the flange, which is usually small in this 
species, widened out into a broad expansion with an extensive venation of 
its own. The extraordinary instability which is thus seen in B. capense may be 
compared with that to be described below in B . punctulatum , but it will be seen 
that the two species have brought about the change in rather different ways, 
though the result of obliteration of the dimorphism is the same in both. 
The vascular system of the axis is in essentials on the plan above 
described ; the petiole also, except that it shows a rather higher complexity 
owing to subdivision of the leaf-trace strands. In a large petiole at the level 
of the lower pinnae, the horseshoe-like series of strands may number ten or 
eleven, but the two on the adaxial side are always the largest and show the 
usual xylem-hooks. 
In the development of the fertile pinna the usual marginal segmentation 
is found, and the whole of the lateral wing is referable to it (PL XXV, 
Fig. 11, a). The initial cell itself remains at the margin of the flange, but 
the latter does not normally develop to any great size. Some distance 
inwards from the margin a massive upgrowth appears upon the lower 
surface (Fig. 11, a, b). This produces the receptacle and indusium, which 
together are rather more robust than in B. spicant , and the indusium soon 
projects as a body of considerable dimensions, overarching the receptacle 
(Fig. 11, e). In the mature state there is a strong vascular commissure, 
which runs under the receptacle, and, as in B. spicant , the venation extends 
outwards into the flange, which is here quite of appreciable size. 
(H) B. gibbam (Lab.), Mett. 
This species need not be examined in detail. It is a subdendroid type, 
in habit very like B. discolor , and the leaves are commonly dimorphic. But 
the point of interest for us is that the fertile pinnae are again variable. 
Sometimes they are narrow, with a hardly perceptible flange, but in other 
cases there may be considerable expansion of it, so as to supply a large 
assimilating surface. It is thus susceptible of an instability similar to 
that of B. capense . A state of this species which very nearly resembles 
B. brasiliense has even been described as var. blechnoides. 
The species above described are all included by systematists in the 
sub-genus Lomaria . They give a fair representation of that type and 
show that it includes chiefly upright, or even subdendroid, forms; they 
illustrate various conditions of the fertile pinna from those in which a ‘ flange’ 
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