493 
Stiles. — The Podocarpeae. 
canals. In A gat his these alternate with the vascular bundles, whereas in 
Nageia, as has been already observed, a single resin canal is present under 
each vascular bundle, and from the constancy of this character throughout 
the order it seems reasonable to attach importance to it. There is thus no 
convincing evidence that within the Podocarpeae the single-veined leaf has 
been derived from the many-veined one. 
On the other hand, the evidence in favour of the greater primitiveness 
of the uninerved leaf seems more convincing. In the first place, with regard 
to leaves within the order, we find single-nerved leaves occurring in all the 
genera, while pluri nerved leaves are found in one section of one genus only, and 
that genus the one which on general grounds must be admitted to be the least 
primitive in the order. In the second place, leaves of a closely similar structure 
are found in all other orders of Coniferae. In Araucaria Rulei 1 there is 
a single resin canal beneath the single vascular bundle as in the Podocarpeae, 
and, moreover, of all the Araucarieae it is this species which approaches most 
nearly Saxegothaea , not only in this respect, but also in the structure of the 
microsporangium , 1 2 in the gradual transition between leaves and megasporo- 
phylls , 3 and in the vascular anatomy of the megasporophyll . 4 It is also of 
significance that Seward and Ford regard the leaf of A. Rulei as constituting 
in some measure a link between the two sections of the genus Araucaria. 5 
In the Taxeae also a leaf with a very similar structure prevails. The leaf 
of Taxus scarcely differs from that of Saxegothaea except in the absence of 
the resin canal from the former. Among the Abietineae the leaves of Tsuga 
Mertensiana and T. Pattoniana closely resemble those of Saxegothaea, while 
the leaves of other species may well be derivable from this type. Similarly, 
among the remaining orders, Taxodieae and Cupressineae, leaves with a not 
very different structure are found. These facts seem to me to point to this 
type of leaf as not only primitive in the Podocarpeae, but in the Coniferae 
as a whole . 6 It is of course possible here, as elsewhere, to invoke reduction, 
but it seems an extraordinary thing if in all the Coniferous phyla the reduc- 
tion from the primitive type has been so great, and yet has produced so 
nearly the same result in each case. 
From these considerations it seems to the writer probable that the 
Saxegothaea type of leaf is the primitive one in this order, and that the 
Nageia type has probably been derived from the single-veined leaf, not 
merely during the course of phylogeny of the Podocarpeae, but during that 
of the genus Podocarpus itself. 
The primitive Podocarpean plant can then be pictured as a tree, 
bearing probably spirally arranged leaves of a Yew- or Saxegothaea- like 
1 Seward and Ford (’06), p. 350. 2 Stiles (’08), p. 212. 
3 Seward and Ford (’06), p. 361 ; Stiles (’08), p. 213. 
4 Stiles (’08), p. 217. 6 Seward and Ford (’06), p. 351. 
6 Compare the remarks of Coulter and Chamberlain (’10), p. 225. 
