XXVII LEPINIA TAHITENSIS 379 



very evident capacity for dispersal, has not been recorded from any 

 other localities in the Pacific than the far-separated Solomon and 

 Tahitian Groups. There is a suspicion that, as in the case of the 

 residual genera of Hawaii, America may have contributed some of 

 the original plants, since three of the genera, Buttneria, Coriaria, 

 and Bidens, occur in that continent, and in the case of Coriaria 

 Tahiti possesses a species found in South America as well as in 

 New Zealand. 



One of the trees in question is Cratseva religiosa, an Asiatic 

 species, which may be placed among a group of trees, including 

 Cananga odorata and Fagraea Berteriana, which, whilst they are 

 much esteemed by the inhabitants of the South Pacific for their fruits 

 or their flowers, and are often planted in and around their villages, 

 possess fruits that attract birds, and in the case of Cananga are 

 known to be dispersed by fruit-pigeons. Probably the aborigines 

 and the birds have worked together in the distribution of these 

 trees. 



The genera Buttneria of the Sterculiaceae and Berrya of the 

 Tiliaceae are represented in this region by species that must owe 

 their dispersal to birds, though I have no data relating to the matter 

 of their dispersal, their fruits being capsular, in the first case prickly. 

 Coriaria is a mountain genus in Tahiti and will be found dis- 

 cussed in Chapter XXIV. in connection with the Tahitian mountain- 

 flora. Its absence from the West Polynesian groups is no doubt 

 to be connected with their insufficient altitude. In addition to 

 the introduced Bidens pilosa, a common tropical weed, Tahiti 

 possesses two other truly indigenous species of Bidens, of which one 

 at least is peculiar to the region. The achenes of this genus are 

 well known to be adapted for dispersal in a bird's feathers ; and 

 since the genus has its principal home in America, no other indi- 

 genous species having been recorded from South Polynesia, it is not 

 unlikely that the parent species was American. 



One of the numerous enigmas of the Pacific floras is con- 

 cerned with the presence in the islands of Tahiti and Moorea 

 (Eimeo), in the Society Group, of the Apocynaceous tree, Le- 

 pinia tahitensis. The genus contains this solitary species, which 

 has been collected only in one other locality, namely, in the 

 Solomon Group, where it was obtained by the Rev. R. B. Comins. 

 Such an instance of disconnected distribution is rare in the Pacific 

 Islands, and undoubtedly it represents one of the difficulties of the 

 Tahitian flora. The fruits, which are indehiscent and five or six 

 inches in length, possess a fibrous pericarp and a single seed. 



