xxvii BYRONIA 371 



and Vaccinium have been discovered in the more elevated uplands 

 of Savaii in Samoa. 



After removing the littoral plants and the mountain genera, 

 there are probably not more than half a dozen inland genera that 

 connect the Hawaiian lowlands with the Tahitian region to the 

 exclusion of the Fijian Group ; and Byronia (Ilicineae), Reynoldsia 

 or Trevesia (Araliaceae), Phyllostegia (Labiatae), and Pseudomorus 

 (Urticaceae) may be taken as examples. Of these, Pseudomorus, 

 which has a small drupaceous fruit suitable for dispersal by 

 frugivorous birds, has been recorded from New Caledonia, and not 

 improbably it exists in the Fijian area ; and the same may be 

 postulated of Reynoldsia, which is discussed in a later page, since it 

 has been found in Samoa. We may almost form the same opinion 

 of Byronia, since it exists in Australia. This genus of small trees 

 contains only three known species, one in Australia, one in Tahiti, 

 and one in Hawaii. Its fleshy drupes, about a third of an inch 

 (8 mm.) in size, would attract birds, and their numerous cartila- 

 ginous pyrenes would probably pass unharmed through a bird's 

 alimentary canal. Phyllostegia, a Labiate genus with fleshy 

 nucules that might attract birds, is, with the exception of a 

 solitary Tahitian species, entirely confined to Hawaii (see Chapter 

 XXII.). 



From these data it may be inferred that the interchange of 

 plants between the regions of Hawaii and Tahiti to the exclusion 

 of Fiji has been very slight. The facts of distribution are just 

 such as we might look for in the case of a general dispersal over 

 the oceanic groups of the tropical Pacific, with the altitudes of the 

 islands playing a determining part. In this general dispersal 

 Hawaii has shared ; and except in the case of Phyllostegia it is 

 evident that this group has kept nearly all it received and has 

 distributed but little. 



HAWAIIAN GENERA FOUND IN FIJI TO THE EXCLUSION OF 



TAHITI. 



We shall be able to throw further light on the floral history of 

 Hawaii by discussing the few tropical genera, not a score in all, 

 that it possesses in common with Fiji to the exclusion of the 

 Tahitian region. The following genera offer themselves for treat- 

 ment : Eurya (Ternstrcemiaceae), Gouania (Rhamnaceae), Maba 

 (Ebenaceae), Sideroxylon (Sapotaceae), Antidesma (Euphorbiaceae), 

 Pleiosmilax (Smilaceae), and Ruppia (Potameae). 



B B 2 



