Antiquity of the Angiosperms — SUESSENGUTH 
endemic. Relatively speaking, they show the 
smallest number of endemics among the 
angiosperms, which is rather an interesting 
fact, inasmuch as in the flora of European 
countries a certain parallel can be found for 
these values (Schmidt, 1945). 
The smaller percentage of endemics among 
the Pteridophytae may be explained by the 
fact that the ferns are more readily dissem- 
inated over greater distances by means of 
their spores. It may be that in this manner 
many species of ferns immigrated into Aus- 
tralia, or emigrated from it, after its geo- 
graphical isolation had begun. The same 
supposition is valid for many species of the 
Gramineae and for the Cyperaceae among 
the Monocotyledones. 
When we consider the great number of 
endemics present in the Australian flora, we 
are tempted to jump to the important con- 
clusion that, in later times, only an inconsid- 
erable migration of plants took place into 
Australia from abroad. If there had been any 
considerable degree of migration, we should 
be able to find the species of plants now liv- 
ing in Australia spread over other continents 
as well, and especially over Malaysia. Ac- 
tually, however, they are not so widely dis- 
tributed, but are confined as endemics to 
Australia. The evidence is such that we may 
safely conclude, therefore, that a pronounced 
development of species took place on the 
Australian continent after the geographical 
isolation had begun. But, if few species have 
migrated into Australia from abroad over 
such a very long time (except in the cases 
of the Pteridophytae, which show the fewest 
endemics), is it not probable that all of the 
types which evolved into endemic species 
were already in existence before the period 
of geographical isolation, that is, during the 
Upper Cretaceous period? Did the numerous 
representatives of the characteristic families 
of the Australian flora already flourish in 
those ancient times? Was the Australian flora 
of those days similar, at least in its families, 
291 
to the Australian flora as it is now? Above 
all, did all of the many families of the Aus- 
tralian flora exist then as they do now? These 
questions are not easy to answer, and before 
investigating them it will be useful to give a 
rather detailed account of the Australian flora 
itself. 
To begin with, it must be accepted that 
the evolution of the families of the flowering 
plants had begun in times earlier than those 
of the Upper Cretaceous period, for only a 
very few endemic families are found in Aus- 
tralia, and these have only a very few species 
in them. These families are the Akaniaceae, 
Balanopsidaceae (which also appears in New 
Guinea), Brunoniaceae, Byblidaceae, Cepha- 
lotaceae, and Tremandraceae. These are the 
only families that have developed endemically 
in Australia since the Upper Cretaceous pe- 
riod, although they might possibly have been 
preserved in Australia from times even more 
ancient than the Upper Cretaceous; since that 
period there has not been time enough for 
a further evolution of families. From this 
evidence we can conclude that it is very likely 
that the primitive ancestral types of the other, 
much larger, families of the Australian flora 
existed during the Upper Cretaceous period. 
If they had immigrated into Australia after 
Upper Cretaceous time — which is a possibil- 
ity we naturally have to take into considera- 
tion — then they ought to be found in other 
parts of the world as well. We shall learn 
later in detail how far this is true. But, in 
any event, we must not assume that the six 
endemic Australian families also existed, at 
one time, in other parts of the world, only 
to die out later in those places, so that now 
they are native to Australia alone. We must 
be cautious with this kind of conclusion, a 
lesson which has been made obvious by the 
example of the mammals of New Zealand, 
referred to by Diels (1897) in his work on 
the vegetative biology of New Zealand. We 
shall return to this matter later in this paper. 
