CHAP. XXII.] THE FLORA OF NEW ZEALAND. 
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temperate South American, many being also Antarctic or 
European; while others again are especially tropical or Poly- 
nesian ; yet undoubtedly a larger proportion of the Natural 
Orders and genera are common to Australia than to any other 
country, so that we may say that the basis of the flora is 
Australian with a large intermixture of northern and southern 
temperate forms and others which have remote world-wide 
affinities. 
1 General features of the Australian Flora and its probable 
Origin . — Before proceeding to point out how the peculiarities 
of the New Zealand flora may be best accounted for, it is 
necessary to consider briefly what are the main peculiarities 
of Australian vegetation, from which so important a part of 
that of New Zealand has evidently been derived. 
The actual Australian flora consists of two great divisions — 
a temperate and a tropical, the temperate being again divisible 
into an eastern and a western portion. Everything that is 
characteristic of the Australian flora belongs to the temperate 
division (though these often overspread the whole continent), 
in which are found almost all the remarkable Australian types 
of vegetation and the numerous genera peculiar to this part of 
the world. Contrary to what occurs in most other countries, the 
tropical is far less rich in species and genera than the temperate 
region, and what is still more remarkable it contains com- 
paratively few peculiar species, and very few peculiar genera. 
Although the area of tropical Australia is about equal to that 
of the temperate portions, and it has now been pretty well 
explored botanically, it has less than half as many species. 1 
1 Sir Joseph Hooker informs me that the number of tropical Australian 
plants discovered within the last twenty years is very great, and that the 
statement as above made may have to be modified. Looking, however, at 
the enormous disproportion of the figures given in the “Introductory 
Essay” in 1859 (2,200 tropical to 5,800 temperate species) it seems hardly 
possible that a great difference should not still exist, at all events as 
regards species. Sir Joseph Hooker also doubts the generally greater 
richness of tropical over temperate floras which I have taken as almost an 
axiom. He says: “Taking similar areas to Australia in the Western 
World, e.y., tropical Africa N. of 20° as against temperate Africa and 
Europe up to 47°' — I suspect that the latter would present more genera and 
