Dispersal of Herbaceous A ngio sperms. 589 
F. Northern Plants in the Antipodes. 
The occurrence in the floras of Australia, New Zealand, Patagonia, South 
Africa, and Madagascar of a very large number of genera and species charac- 
teristic of the north temperate and even of the arctic zones has been noted by 
many botanists as one of the most striking features of the vegetation of the 
Antipodes. Sir Joseph Hooker enumerates 125 genera and even 42 species 
which are common to Europe (many of them to America also) and to the 
4 Antarctic ’ floras, and this list has since been considerably extended, so that 
at least 21 7 typically northern genera are now known to occur in the south 
temperate zone. 
The present distribution of these plants and their allies seems to 
indicate very clearly that they have not had their origin in the southern 
hemisphere, but have entered it as immigrants from a centre of distribution 
somewhere in the north. That this immigration was not an ancient one 
but has been comparatively recent is indicated by the slight degree of 
endemism appearing in the northern types. Change has evidently not 
been great enough to cause the creation of distinct genera, for the genera 
endemic in the Antarctic floras are but rarely related closely enough to the 
northern types to suggest an origin from them in situ. Still more con- 
clusive is the presence of a large number of species, even, which are 
identical with those in distant regions of the north. It is extremely hard 
to believe that so many plants could have preserved their identity for a very 
long period of time. 
But in this great invasion which has spread the 4 Scandinavian 5 flora 
throughout most of the southern lands, it is significant that not all northern 
types have participated. It has been in reality an invasion of herbs , for 
198 out of 217 characteristic northern genera, or 96 per cent., including all 
those rich in species (save Erica), are composed of herbaceous plants. The 
nine woody genera are Rubus , Ribes , Berber is, Sambucus , Salix , Myrica , 
Empetrum , Erica , and Vaccinium. Of these Erica and Myrica occur only 
in South Africa. All the genera save Erica are very poor in species, and 
they compose but an insignificant part of the northern element in the flora. 
All the Antarctic species identical with northern ones are herbs. 
All these facts are in harmony with our hypothesis that the majority 
of herbaceous plants have had their origin in the continental area 
of the north temperate zone, and that they have developed comparatively 
recently in adaptation to the progressive refrigeration of the climate. The 
enormous number of species and genera produced in this great and 
continuous land mass, in contrast to such regions as Australia, New 
Zealand, and Patagonia, has probably been due to the opportunities for 
easy dispersal over a wide area, with the consequently tremendous increase 
in number of individuals and their exposure to many different environments. 
