604 CONCLUSION 
In point of the positions which they hold on the shoot the two types of 
spore-producing members, the sporangia and sporangiophores, show some 
degree of uniformity: in either case the insertion may be directly upon 
the axis or in the axil of the sporophyll, or they may be inserted further 
outwards upon the surface of the sporophyll. Leaving for the moment 
the Ferns on one side, illustrations may be taken from the strobiloid 
types. As regards the simple sporangia, these may originate from the 
axis quite apart from the subtending leaf, as in Se/agine//a (Fig. 360): in 
Lycopodium the sporangium arises from the upper surface of the leaf close to 
its base (Fig. 3608, c); but in Spencerites it is borne at a point far removed 
from the leaf-base, though otherwise in accordance with the Lycopod-type 
(Fig. 360D). Similarly with the sporangiophores, the insertion may be 
Fic. 360. 
Diagrams illustrating the varying positions respectively of sporangia (upper row) and 
of pe ae (lower row). It is seen that a parallelism exists. For details 
see Text e 
on the axis or on the sporophyll, but they show rather more latitude of 
detail: thus in Zguzse¢um and in the ancient Archacocalamiles they are 
seated upon the axis, showing no association with bract-leaves (Fig. 3605): 
or in Calamostachys whorls of bracts may intervene between the successive 
whorls of sporangiophores, but without individually subtending them (Fig. 
360F): or the sporangiophore may, possibly by a secondary displacement, be 
apparently axillary, as in Palaeostachya (Fig. 360): or, again, the sporangio- 
phore may arise from the upper surface of a sporophyll, in which case it 
necessarily has a subtending position, as,in the Psilotaceae (Fig. 3601): 
a similar position is seen in Sphenophyllum majus (Fig. 360 4), but 
in other species of the genus there are more complex arrangements 
probably resulting from fission! From such examples as these it appears 
1Scott mentions a species (5. evarginalun) which appears to have borne its sporangio- 
phores separately, so that they ‘‘have left their own distinct scars on the axis above 
the bracteal node” (Progressus, i. p. 153). This arrangement closely approaches that 
of Palacostachya, or of Calamostachys. 
