THE ORIGIN OF THE HAWAIIAN FLORA 
By Попсълз HOUGHTON CAMPBELL 
Leland Stanford Junior University 
The Hawaiian Islands afford perhaps the most important 
problem in plant distribution that exists anywhere. The most 
isolated land area of equal size on the globe, the origin of their 
extremely peculiar and interesting flora opens a wide field for 
research and speculation. 
There is much difference of opinion as to whether or not the 
Islands have had at any time connection with any of the great 
continental areas. Hillebrand,* whose flora of Hawaii is well 
known, and has been followed in the tables given in this paper, 
believed that the Islands had always been isolated, having been 
thrown up from great ocean depths through volcanic action. 
This view has been recently advocated by Muir} as the result of 
his studies on the insect fauna of the islands. Оп the other hand, 
Wallace,t on the basis of the occurrence of certain north temperate 
genera in the high mountains of Hawaii, believed that there had 
been a land connection with west North America. Recently, 
Pilsbry$ has brought forward evidence which he thinks proves 
conclusively some ancient connection of the Islands with the 
Malaysian region. The peculiar land-snails, so largely developed 
in the Islands, are, according to Pilsbry, ancient forms, whose sur- 
vival outside of the Pacific Islands is known only in the Malaysian 
region. 
The writer, up to the present time, has taken it for granted 
(largely on Hillebrand's evidence) that the Islands always had 
been completely isolated; but the evidence offered by Pilsbry for 
an ancient land connection seems very strong, and, moreover, is 
* Hillebrand, W. Flora of the Hawaiian Islands. 1888. 
T Muir, F. Proc. Haw. Ent. Soc. 3: 198—200. 1916. 
t Wallace, A. В. The geographical distribution of animals, I: 447. 
$Pilsbry, H. A.  Mid-Pacific land-snail fau 
1876 
и 1 aunas. Proc. Nat. Acad. Sci. 3: 
429-433. 1916. 
+ 
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