The Grouping of Vascular Plants 85 
A single vein occurs in some Conifers but the leaf trace is 
generally at least dual and leaves of different species of the same 
genus may have one vein or a trace that segments palmately as 
in species of Podocarpus and Araucaria. There is ample evidence 
that the leaf of the Cordaitales, Ginkgoales and Coniferae falls within 
the Meiophyll type. 
In Podocarpus each of the pair of cotyledons has two bundles, 
and the generally accepted interpretation of polycotyledony in the 
Conifers is that it is due to segmentation of an original pair. Ample 
evidence of this is given in the papers by T. G. Hill and E. de Fraine, 
I to III “On the Seedling Structure of Gymnosperms 1 . ” Not only 
the cotyledons of Ginkgo but all the foliage leaves are more or less 
lobed and this lobed, flabelliform leaf was especially characteristic 
of the ancient type of Ginkgoales called Baiera 2 . 
In the Cordaitalean circle of affinity there is no example known 
of a leaf with the veins branching otherwise than in the dichoto¬ 
mizing palmate method found in Meiophylls. It appears to the 
writer that such uniformity points to an important ancestral re¬ 
semblance and probable affinity between the Sphenopsida and this 
ancient group of Families. 
Let us turn now to the consideration of the insertion of the 
soroma and deal first with the megasoroma or seed. We find as 
pointed out in the discussion of the subject in the 1908 paper, “The 
Sporangiophore,’’ we are possibly “dealing with plants which have 
never had their * sporangiophores ’ taken up upon leaves and that, 
in fact, they are constructed in this respect upon the Equisetal plan 
where the sporangiophores are merely associated with bracts 3 /’ 
This view has been adopted tentatively by Sahni in his recent 
review of the entire Gymnospermous series appended to his Mono¬ 
graph on Acmopyle Pancheri Pilger 4 . He shows there are two great 
divisions based primarily upon the manner in which the seed is 
borne, whether upon the leaf, or directly upon the axis. These two 
divisions he calls the Phyllosperms (leaf borne seeds) including the 
Cycadales and Pteridosperms, and the Stachyosperms (stem borne 
seeds) including the Cordaitales, Ginkgoales, Taxalesand Coniferales. 
1 Hill and de Fraine, Ann . of Bot . 22, p. 689, and 23 , pp. 189 and 433. 
2 See Seward's Fossil Plants , 4 , pp. 1-60, where the Meiophyll type of leaf 
is well illustrated. 
3 Loc . cit . p. 149. 
4 Prof. Birbal Sahni, Phil . Trans . Roy . Soc . Land . Series B, 210, pp. 299- 
302. 
