Malaysian Phytogeography in Relation 

 to the Polynesian Flora 



By E. D. Merrill 



IN ANY GENERAL TREATMENT o£ the flora of Polynesia, whether 

 this be merely a taxonomic consideration or a discussion of 

 the phytogeography of the region and the relationships of 

 the flora to that of surrounding lands, it is manifest that the vege- 

 tation of the islands that form the western boundary of the 

 Pacific is a major factor to be considered. At the present time, 

 representatives of between 1400 and 1500 more or less generally 

 recognized genera of flowering plants and ferns are known from 

 Polynesia. However, this estimate includes New Caledonia, 

 which is remarkable for its very specialized flora, and comprises 

 the very numerous exotics introduced by man. More than iioo 

 of these genera occur also in Malaysia. 



Essentially, the flora of Polynesia, whether we consider that 

 of the low or the high islands, is Malaysian in origin, with certain 

 characteristic Australian elements which also occur in Malaysia 

 and particularly in Hawaii, with a small admixture of American 

 forms. No single family of plants is confined to Polynesia, and 

 the number of endemic genera is relatively small. Specific en- 

 demism in the low islands is very limited, most of the species 

 being those of wide tropical distribution. With the exception of 

 the weeds and cultivated plants introduced directly or indirectly 

 by man, the flora of the low islands is chiefly composed of species 

 having special adaptation for dissemination by ocean currents. 

 However, in each of the groups of high islands in Polynesia 

 there is a distinctly high specific endemism, which is in general 

 true of oceanic islands, but the relationships of these endemics 



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