Plant Invasions of New Zealand with Reference to 
Lord Howe, Norfolk, and the Kermadec Islands. 
J, C. WILLIS, M.A., Sc.D., F.R.S., 
European Correspondent of the Botanic Garden , Rio de Janeiro. 
With three Diagrams and eleven Tables in the Text. 
I N a series of eight papers in this journal, 1916—19, I have dealt with the 
floras of New Zealand proper and the islands which outlie from it to 
the north (Kermadecs), east (Chathams), and south (Stewart and Aucklands), 
islands which must have received a large part of their flora either directly 
from New Zealand or from invasions which passed near to them on the way 
thither. In these papers I have made a great many predictions based upon 
my hypothesis of age and area, and have always found them borne out by 
the facts. It is almost needless to say that in some cases these facts were 
already known to New Zealand and other botanists, though very many are 
new. My chief object in making all these predictions was to marshal the 
facts and to show (and I venture to think that I have shown) that age and 
area can be relied upon as a guide in the taxonomic distribution problems 
of a well-defined area like New Zealand and its immediately outlying 
islands. I shall now go farther afield, and endeavour to trace farther towards 
their source some of the invasions of plants which appear to have reached 
New Zealand from the north or north-west. 
One of the principal objects kept in view in this work is to show that 
the floras of the islands which lie between New Zealand and Australia or 
Polynesia fit in with my hypothesis of age and area, and are explicable on 
that hypothesis ; further, that they are also capable of being dealt with by 
aid of numerical methods, like,. the floras of New Zealand itself, and, there- 
fore, that the invasions of plants must have been by land — casual trans- 
aqueous carriage would not produce such results. 
In the first papers of this series, dealing with Ceylon ( 7 ), by means of 
statistics of actual distribution of the various species, which were taken from 
Trimen’s Flora, and which showed that the least widely distributed species 
in the island were those confined to Ceylon, the next those confined to 
C eylon and South India, and the most widely distributed in the island those 
[Annals of Botany, Vol. XXXIV. No. CXXXVI. October, 1920.J 
