5 °° 
Arbor and Parkin . — Studies on the 
no homologue of a perianth. In ‘ Die Angiospermen und die Gymnospermen ’ 
he concluded that all the envelopes are integuments, in which case Gnetum 
may possess three. But in our opinion the strong argument against this 
view is that in the male fructifications of both Gnetum and Ephedra (Text- 
fig. 2) an envelope is present, which cannot be integumentary, but which is 
obviously of the same morphological value as the outer envelope of the 
female fructification found in all three genera. For from the male strobilus 
of W elivitschia , where this perianth is less reduced, and consists of two 
cycles of two members each, we can easily derive the single perianth whorls 
found in all the female strobili, and also in the male of Ephedra and Gnetum. 
On Strasburger’s view the male fructification of Welwitschia is unintelli- 
gible, and has no phylogenetic significance. 
The Aggregates of Strobili. 
The fructifications of the Gnetales do not, as is well known, occur as 
isolated reproductive shoots, but are aggregated into dense groups, which 
in Welwitschia and Ephedra are somewhat cone-like in external appearance. 
These aggregrates of strobili may be further collected together, apart from 
the purely vegetative organs, to form a system of reproductive shoots, which 
may be closely compared with complicated inflorescences found among 
Angiosperms. We regard such aggregates as indicating a high degree 
of evolution, and a far from primitive state. For we would apply here the 
same reasoning as in the case of the Angiosperms, where we have shown 
that the presence of a dense and complicated inflorescence, correlated with 
a much reduced perianth and unisexual flowers, may be recognized as a sign 
of a highly evolved state, derived originally from plants possessing solitary, 
hermaphrodite flowers with a conspicuous perianth. 1 The Gnetales thus 
appear to us to afford another instance in which the tendency of speciali- 
zation has been in the direction of the inflorescence rather than of the 
individual flowers, and here, as is so often the case among Angiosperms, 
it is correlated with a great reduction in the less essential floral organs, 
and with the evolution of unisexuality. 
The aggregates of Ephedra are fairly simple, the male strobili being 
arranged in compact spike-like groups, each containing several strobili. 
These spike-like groups may be clustered together on neighbouring 
branches. The female fructifications are also borne in similar groups, which 
however contain only 1-3 strobili. In some Ephedras female strobili may 
occur at the apex of the male spike-like branches. 2 
The aggregates in Welwitschia are essentially similar to those of 
Ephedra , though rather different in size and appearance, the female spike- 
groups being very much larger, and recalling somewhat the cones of the 
Coniferae. In both the male and female aggregates, several strobili occur. 
1 Arber and Parkin (’07), pp. 38-42. 2 Wettstein (’07 2 ). 
