The Geographical Affinities of the South Pacific 
Island Fern Floras 
G. Brownlie 1 
ABSTRACT: The theory is proposed that the fern floras of the South Pacific, 
while being predominantly recently Malaysian in origin, consist also of two older 
elements, one being relics only of an ancient world-wide flora, the other an earlier 
Malaysian invasion confined now to the older and larger islands only. A fourth 
minor element is a recently evolved southern or subantarctic group. 
Much has been written in texts on plant 
geography on the importance of Pacific island 
floras, and many papers have discussed the ele- 
ments present in these floras, but these have 
relied largely on analyses of the phanerogams 
only. It is felt that the other groups of plants 
may yield as much information of interest, and 
an attempt is made here to examine the fern 
floras of the South Pacific from this point of 
view. Most of these floras are fairly well-known 
now, although written information for the New 
Hebrides is scattered, and material for the Solo- 
mons is very incomplete. 
The most outstanding immediate impression 
is the gradual reduction in number of species 
from the Solomon Islands eastwards and south- 
wards. Most of the smaller islandrof course do 
not possess the range of habitats suitable for 
the establishment or development of a very di- 
verse flora, but this general principle still ap- 
plies to relatively large high islands. Copeland 
(1929) admits 230 species for Fiji, Christen- 
sen (1943) lists 213 for Samoa, Copeland 
(1932) gives 150 for the Society Islands, while 
New Zealand also possesses 150 species. By 
contrast with this, at least 300 species are 
known from New Caledonia with probably a 
much greater number in the islands to the 
north. 
Elevation also plays a vital role in the di- 
versity of fern floras, islands with sufficiently 
high mountains to develop a definite mist zone 
1 Department of Botany, University of Canterbury, 
Christchurch, New Zealand. Manuscript received No- 
vember 27, 1963. 
having a very much greater number of species 
than low-lying islands in the same area. Wet 
mountain forests throughout the tropics are 
always the sites of the most prolific display of 
specific and generic variety. In Borneo, of the 
total of some 700 species, approximately 400 
have been recorded from the single large mas- 
sif of Mt. Kinabalu. An example of the dif- 
ference that this factor makes is shown by a 
comparison of the flora of New Caledonia 
with that of the neighbouring low-lying Loy- 
alty Islands. The latter possess only about 30 
species — all widespread ferns or local variants 
of widespread species, and none of the typi- 
cally New Caledonian groups are represented. 
This flora, which may almost be called a tropi- 
cal weed fern flora, is characteristic of all low 
Pacific islands, the same species occurring 
throughout. On atolls the number of species is 
further reduced, but all are members of this 
same group. 
The majority of fern genera are so wide- 
spread geographically that any attempt to dis- 
tinguish relationships, evolution, and directions 
of distribution using this rank as a criterion 
becomes meaningless. This does not exclude 
the possibility that experimental work within 
any genus will not give hints as to the evolu- 
tion of the genus, and of relationships both 
within the genus and to other genera, but most 
investigations of this type would need to be 
carried out on such a vast scale that they would 
occupy more than one researcher’s lifetime. 
Consequently the pattern of specific distribu- 
tions has been found the most productive in 
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