CHAPTER XXVI 



THE MALAYAN ERA OF THE NON-ENDEMIC GENERA OF 

 FLOWERING PLANTS (continued) 



THE AGE OF WIDE DISPERSAL OVER THE TROPICAL PACIFIC 



(continued) 



The widely dispersed genera that are as a rule not entirely represented by 

 endemic species in any archipelago. Elaeocarpus. Dodonasa. Metro- 

 sideros. Alyxia. Alphitonia. Pisonia. Wikstrcemia. Peperomia. 

 Eugenia. Gossypium. The last stage in the general dispersal of plants 

 of the Malayan era as illustrated by the widely-dispersed genera having 

 as a rule no peculiar species. Rhus. Osteomeles. Plectronia. Boer- 

 haavia. Polygonum. Pipturus. Dianella. Summary. 



A LATER period in the era of the general dispersal of Malayan 

 plants over the Pacific is indicated by those genera that as a rule 

 are never entirely represented by endemic species in any archi- 

 pelago. Hawaii now comes into touch with the world outside, and 

 all the groups possess some connecting link. But the beginning 

 of the effect of the isolating influence is shown in the association in 

 each principal archipelago of peculiar species with those that occur 

 in other groups. 



We see here illustrated in all but the final stage that process by 

 which a solitary widely-ranging species, alone representing its 

 genus, becomes ultimately in each group the parent of a number of 

 peculiar species. The polymorphous, or extremely variable, species 

 plays in this period the all-important part. The earliest stage 

 is exhibited by such genera as Alphitonia, Dodonaea, Metrosideros, 

 Pisonia, and Wikstrcemia, that possess in the tropical Pacific 

 a solitary widely-ranging species, varying independently in every 

 group and giving rise to forms that, in their degree of differentia- 

 tion, sometimes approach a specific value. Later stages are shown 



