xxvn HAWAIIAN RESIDUAL GENERA 361 



the isolated position of the group. The want of variety, however, 

 in the flora of the Hawaiian lower levels, which up to 4,000 

 or 5,000 feet represent the islands of the less elevated Fijian 

 region, is in a small degree compensated for by the development 

 of new genera and new species and by the great number of 

 individuals. Trees like Metrosideros polymorpha and Aleurites 

 moluccana, that in the southern groups form only one of many 

 contributors to the forests, rise suddenly into prominence in 

 the northern archipelago and form entire forests. Pandanus 

 odoratissimus largely composes extensive forests in the province of 

 Puna in the large island of Hawaii, extending several miles inland 

 and nearly 2,000 feet up the mountain slopes. 



The remarkable contrast between the Fijian flora, which is 

 almost entirely tropical, and the Hawaiian flora, which on account 

 of the great elevation of the islands is temperate as well as tropical, 

 is brought into yet greater prominence when we look at it more 

 closely and treat it numerically. The Hawaiian Group, it must be 

 first observed, though possessing the same area as Fiji and present- 

 ing a far greater variety of climatic conditions, has only two-thirds 

 the number of genera of flowering plants (see Chapter XXL, 

 Table B). Whilst at least 200 of the Fijian genera of indigenous 

 plants (excluding the orchids and the grasses) are not found 

 in Hawaii, only about 100 of the Hawaiian genera are absent from 

 Fiji, and the two groups possess about 100 genera in common. 

 When we look more closely at the hundred Hawaiian genera 

 not found in Fiji, we find that about sixty represent endemic 

 genera (thirty-seven) and non-endemic mountain-genera (twenty- 

 two), which naturally are not to be found in Fiji, so that there 

 remain but a small number of genera distinguishing the tropical 

 flora of Hawaii from the Fijian flora. When we take from 

 them a few that occur in the Tahitian region, there is left a 

 very small residuum characteristic of Hawaii alone to the 

 exclusion of the Fijian and Tahitian regions of the South Pacific. 



The Hawaiian Residual Genera. 



It is my purpose now to deal in an illustrative fashion with this 

 Hawaiian residual flora which is composed, as above explained, of 

 the non-endemic tropical genera that are not represented in the 

 Fijian and Tahitian regions. Up to the present we have been 

 dealing with the characters that the floras of Fiji, Tahiti, and 

 Hawaii possess in common as far as tropical genera are concerned. 



