980 T ho day and Ber ridge* — The Anatomy and Morphology of 
and the more or less regular dichasial branching of the female inflorescences 
of E. altissima is a point of similarity with both the male and female 
inflorescences of Welwitschia. In Welivitschia the individual strobilus is 
elongated and produces numerous fertile bracts and flowers, fifty or there- 
abouts in the female and still more in the male 1 with a few sterile bracts 
at the base . 2 In Ephedra the male strobilus bears only ten to fifteen 
whorls of fertile bracts, and the female strobilus is of still more limited 
growth. It has already been remarked that the strobili of the Alatae 
with their numerous membranous bracts are suggestive of an originally 
greater development than is found at present, and even the bracts themselves 
in these species bear a close resemblance to those of Welwitschia. 
In Gnetum also the male inflorescence is dichasially branched and both 
male and female inflorescences would seem from their general arrangement 
to be comparable with those of Ephedra and Welwitschia. But when we 
come to examine the individual strobili we find that the cupule at each node 
is the equivalent of the pair of bracts at the node in the other genera, 
subtending not two but a cushion bearing six or more ovules in the female 
inflorescence and numerous antherophores and abortive ovules in the male. 
There are many more points widening the gap between Gnetum and the 
other two genera : the ovule has an extra covering and both this and the 
outer integument are radially symmetrical and supplied by numerous 
vascular bundles ; the micropylar tube has a complex mechanism for closing 
it ; the membranous appendages of the male flower have a vascular supply. 
The complicated method of bundle supply 3 of the ovule and antherophores 
in Gnetum is also peculiarly characteristic, while the method of supplying 
these organs in the other two genera is very simple and quite comparable, 
there being, however, no median axillary bundle in W ehvitschia. 
In comparing the individual flowers of the three genera, it is again 
found that Ephedra and Welwitschia show most resemblance to one 
another, though here the signs of relationship are sufficiently clear to justify 
the placing of all three forms in the Gnetales. 
In Welwitschia the male flower consists of an abortive ovule, surrounded 
by a disc of six male sporangiophores fused at their base, and four mem- 
branous appendages. In Ephedra the male flower bears two membranous 
appendages, and evidence has been brought forward to show that the 
antherophore probably consists of a disc of two fused sporophylls surrounding 
an abortive apex . 4 With respect to the form of its microsporophyll (as also 
in its gametophyte) Ephedra appears the more primitive of the two ; each 
1 Pearson, 1906. 
2 The lowest pair of sterile bracts is distinguished from the others by their acute apices ; the 
same characteristic also occurs in the lowest pair of sterile bracts in the male strobilus of Ephedra 
(P- 953). 
3 Thoday (Sykes), 19 n, and Pearson, 1912. 
4 Thibout, 1896, Part III ; Arber and Parkin, Part I, p. 502. 
