XXV CYRTANDRA 



317 



Polynesian species about thirty are Hawaiian, twenty Fijian, fifteen 

 Samoan, and twelve Tahitian ; whilst solitary species are restricted 

 to Tonga and Rarotonga respectively. 



The most significant feature in the distribution of this genus in 

 Polynesia is not only, as is pointed out by Mr. Clarke, that every 

 group has its peculiar species, but that very few species are found 

 in more than one group, and that even in the same archipelago 

 each island has its own species. Thus, of the thirty Hawaiian 

 species, all of which are peculiar to the group, only two or three, 

 according to Hillebrand, are at all generally distributed over the 

 islands, whilst four-fifths have not yet been found to be common to 

 more than one island. So again, all the species found in the 

 Tahitian Group proper are peculiar, with the exception of one ex- 

 tending to the neighbouring Paumotu Islands ; and even Rarotonga 

 has its own species. In the region comprising Fiji, Tonga, and 

 Samoa the same rule prevails, only two or three species connecting 

 the three groups together. There thus seems to be not only a 

 complete suspension of the dispersal agencies between the various 

 archipelagoes, but also often between the several islands of a group. 

 This is particularly to be remarked with the relatively contiguous 

 groups of Fiji, Samoa, and Tonga, since with most other genera a 

 number of species are common to all three archipelagoes. " The 

 polymorphism of the Hawaiian Cyrtandras," says Hillebrand, "is 

 extraordinary : no single form extends over the whole group, and 

 not many are common to more than one island. The variations 

 affect nearly every part of the plant, and branch out and intercross 

 each other to such an extent that it is next to impossible to define 

 exact limits of species." Genera, however, run riot in other groups 

 of the Pacific besides Plawaii, and Reinecke uses much the same 

 language with reference to Elatostema, an Urticaceous genus in 

 Samoa, attributing the wealth of forms to the sensitiveness of the 

 plants to the varying conditions of station (see Chapter XXVII). 



The behaviour of Cyrtandra in the Pacific is rather startling to 

 the student of plant-dispersal when he reflects on the suitability ox 

 the berries for dispersing the plant through the agency of birds. 

 That the vegetation of oceanic islands should be of an endemic 

 character is a fact, remarks Mr. Clarke, that is illustrated by many 

 other orders besides the Gesneraceae. But the point we have to 

 remember is that not only does the genus Cyrtandra display the 

 same prolific character in the large continental islands of Malaya,, 

 such as Java, Sumatra, and Borneo, each of which possesses at least 

 a couple of dozen species, but that this seems to be a feature of the 



