THE MORPHOLOGY AND AFFINITIES OF GNETUM I4I 
lowest Angiosperms. Certainly if this type of Angiosperm was evolved 
from any forms at all closely related to the Gnetales it must have 
been while the latter bore strobili of this spiral type. 
The second kind of abnormal strobilus is illustrated in figures 
2 and 3. It is a staminate one with many abortive ovulate flowers 
massed in several ranks in place of the usual single ring. The stro- 
bilus represented in figure 2 is an old one from which the staminate 
flowers have fallen and on which the ovulate ones have grown con- 
siderably. Figure 3 shows the young condition. If one considers 
the male and female flowers as single stamens and ovules respectively, 
each provided with an envelope, the resemblance of each group with 
its collar to the Ranalean type of flower is striking. Above is a large 
group of ovules; below these, numerous stamens arranged in a low 
spiral; lower still the bracts of the collar. This is the arrangement 
in that type of Angiosperm flower which is considered by many botan- 
ists to be the primitive one. Nevertheless it seems clear that this 
resemblance is only superficial. Evidence will be presented later to 
show that both male and female flowers are themselves reduced from 
the bisporangiate condition. 
3. Anatomy. — Only a preliminary study of the anatomy of the 
strobili, either normal or abnormal, has yet been made. But, in 
addition to the presence of centripetal wood, it has revealed the oc- 
currence of a type of vessel not seen elsewhere in Gnetum. This is 
the familiar type of Ephedra. It will be recalled that the ordinary 
vessel of Gnetum has a single terminal perforation like the vessels of 
most Angiosperms. In fact the possession of this type of vessel is 
perhaps the most remarkable point of resemblance between Gnetum 
and Angiosperms. But in the axis of the strobilus, an admittedly 
conservative region, in place of the single large perforation the vessels 
have a series of enlarged bordered pits from which the middle lamellae 
and tori have disappeared. Now this is the ordinary type of vessel 
of Ephedra. Therefore in this conservative region there persists a 
type of vessel characteristic of the most primitive member of the 
Gnetales — a type which has evidently been derived from the Conif- 
erous tracheid (Thompson, 27). The importance of these vessels 
in connection with the origin of the Angiosperm vessel is obvious. 
The difficulty arises, however, in that the primitive type of Angio- 
sperm vessel appears to have scalariform end walls and not a single 
perforation. 
