38o A NATURALIST IN THE PACIFIC chap. 



No data are to hand relating to the capacities for dispersal possessed 

 by this plant, but it is certain that it has had some means of cross- 

 ing the sea between the adjacent islands of Tahiti and Moorea. 

 (See Hemsley, Journ. Linn. Soc, Bot., xxx. 165.) 



Tahitian Genera found in Hawaii to the Exclusion of 



Fiji. 



This subject has been already discussed in this chapter in 

 dealing with the genera restricted to Hawaii and Tahiti. 



Tahitian Genera found in Fiji to the Exclusion of 



Hawaii. 



Excluding the orchids, sedges, and grasses, as well as the 

 few endemic genera, between sixty and seventy genera, or rather 

 less than half of the genera of the flowering-plants of Tahiti, are 

 found in Fiji to the exclusion of Hawaii. Of these, rather over a 

 half are Old World genera ; about a third occur in both the Old 

 and the New World ; four are confined to Polynesia, and not one 

 is exclusively American. One-third are genera now possessing in 

 the Tahitian region endemic species either entirely or in part, 

 and in such cases we may consider that the agencies of dispersal 

 are now inactive or partially suspended ; the others belong 

 entirely to the present era of dispersal. About half have more 

 or less fleshy fruits fitted for dispersal by frugivorous birds. About 

 a fourth have capsular or other dry fruits that must have been also 

 dispersed by birds preferring a drier diet. Three only possess 

 hairy seeds or fruits suitable for being carried in a bird's plumage, 

 namely, Commersonia, Weinmannia, and Alstonia. There remain 

 about a fourth of the total that are shore-plants dispersed by the 

 currents, being in two cases (Ximenia and Kleinhovia) assisted 

 by birds; whilst Triumfetta, another littoral genus, is probably 

 distributed by birds alone. 



There are no cases of special difficulty from the standpoint of 

 dispersal in these sixty and odd non-endemic genera that Tahiti 

 possesses in common with Fiji to the exclusion of Hawaii. The 

 lack of difficulties connected with the dispersal of all these 

 Tahitian genera is worthy of note, because there are very few 

 difficult genera amongst the rest of the Tahitian flora. Excluding 

 Lepinia tahitensis, which has been already referred to, there are 

 scarcely any " impossible '' plants in the Tahitian region ; and even 

 in this case, when the modes of dispersal of Lepinia come to be 



