290 
PACIFIC SCIENCE, Vol. IV, October, 1950 
TABLE 1 
Representation of Endemic Plants in 
Australia and in Other Parts 
of the World 
REGION 
APPROXIMATE 
PERCENTAGE OF 
ENDEMIC 
PLANTS 
REFERENCE 
Australia 
87.5 
calculated from 
Mueller, 1889. 
New Zealand 
73 
calculated from 
Cheeseman, 1925. 
Hawaii 
90 
according to St. 
John, 1946. 
Galapagos 
40 
calculated from 
Stewart, 1911. 
Sokotra 
33 
according to Drude, 
1896. 
Balkans 
26 
calculated from Ha- 
yek and Markgraf , 
1927-1933, and 
from Turrill, 
1929. 
Iceland 
0 
calculated from Os- 
tenfeld and 
Grontved, 1934. 
For statements about smaller islands, see O. 
Drude, loc. cit. 
it shows; and we may assume that, other con- 
ditions being equal, the percentage of its 
endemism would enable us to measure the 
length of its period of isolation. Scandinavia, 
for example, has very few endemics (and 
these are "weak” endemics in the systematic 
sense ) because there was not enough time for 
it to be overgrown with flowering plants be- 
fore the sparse soil-cover left by the retreat- 
ing glaciers was removed by erosion, and 
because the short period during which allu- 
vial soil has been collecting since glaciation 
has not been long enough for the develop- 
ment of many new species. It is true, of 
course, that Scandinavia can hardly be com- 
pared with Australia, inasmuch as the pre- 
vailing temperatures in Scandinavia are not 
at all favorable for the formation of new 
species (Sterner, 1943: 84). 
Even if we considered as not being en- 
demic to Australia those plants which are 
also found in New Zealand and in Polynesia, 
there remain, nevertheless, 7,501 species, or 
84.8 per cent, which are limited to conti- 
nental Australia and Tasmania. Obviously 
the reduction in number is a minor one. 
An appreciation of the manner of the dis- 
tribution of endemic species among the 
larger plant groups of the Australian flora 
will be gained from Table 2, which shows 
that among the Angiospermae, at least, the 
endemic species are quite equally distributed 
among the three groups into which the angio- 
sperms are divided, with 89.3 per cent for 
the Sympetalae, 90.2 per cent for the Dialy- 
petalae, and 92.9 per cent for the Monoch- 
lamydeae. This high number of endemics is 
not shared by the Monocotyledones, among 
which only 79.7 per cent of the species are 
TABLE 2 
Distribution of Endemic Species among the Larger Plant Groups 
of the Australian Flora 
PLANT GROUP 
TOTAL NUMBER 
OF SPECIES 
IN GROUP 
PERCENTAGE OF 
WHOLE FLORA 
REPRESENTED 
BY GROUP 
NUMBER OF 
ENDEMIC SPECIES 
IN GROUP 
PERCENTAGE OF 
TOTAL NUMBER 
OF ENDEMIC 
SPECIES IN GROUP 
Pteridophytae 
244 
2.7 
124 
50.8 
Gymnospermae 
43 
0.5 
43 
100.0 
Monochlamydeae 
1,130 
12.8 
1,050 
92.9 
Dialypetalae 
3,641 
41.2 
3,286 
90.2 
Sympetalae 
2,229 
25.2 
1,991 
89.3 
Monocotyledones 
1,555 
19.6 
1,240 
79.7 
Totals 
8,842 
100.0 
7,734 
87.5 of the 
total number 
