54 A NATURALIST IN THE PACIFIC CHAP. 



Although in a large island like Hawaii with its lava-bound coasts 

 but few white calcareous beaches exist where we might expect to 

 find such a flora, yet such beaches occur wherever the scanty coral 

 reefs are found off the coast ; and it is just in those localities, as is 

 pointed out in the account of my observations in Note 29, that the 

 " plantes madreporiques " of the French botanists, the plants of 

 the coral atoll and of the reef-girt coast, make their best 

 endeavours to establish themselves. In other islands like Oahu, 

 where coral reefs are more developed, calcareous beaches are more 

 frequent, and there the few " madreporic " plants of Hawaii make 

 a home. 



Nor can the deficiencies in the Hawaiian strand-flora be 

 connected with climatic conditions. That its meagre character 

 cannot be so explained is indicated by the manner in which the 

 Indo-Malayan shore-plants have pushed their way northward on 

 the western side of the Pacific to the Liukiu and Bonin Islands. 

 Here in latitude 26-27 N. we find several Fijian littoral trees and 

 shrubs, such as Hernandia peltata, Pemphis acidula, Pongamia 

 glabra, Sophora tomentosa, Terminalia Katappa, Tournefortia 

 argentea, &c., that do not occur in Hawaii, although this group is 

 some degrees nearer the equator, namely, in latitude 19-22 N. 

 They are accompanied by the mangroves (Rhizophora, Bruguiera, 

 &c.) in strength as far as South Liukiu in latitude 25 N. ; but we 

 learn from Dr. Warburg that the mangroves thin off further 

 north, though they reach to South Japan, where Doderlein found 

 in latitude 32 N. solitary examples of Rhizophora mucronata. 

 These interesting facts of distribution, which are taken from 

 Schimper's work on the Indo-Malayan shore-plants (pp. 85, 90), 

 show us that we can scarcely look to climatic conditions for the 

 explanation of the absence of mangroves and of many other 

 tropical littoral plants from Hawaii. We form the same opinion 

 when we regard the extension northward of the mangrove- 

 formation on the American coasts of the North Pacific Ocean. 

 According to the account of Dr. Seemann given in the " Botany of 

 the Voyage of H.M.S. Herald!' the mangroves with the coco-nut 

 palm, and many other littoral plants common on the western 

 shores of tropical America, reach their northern limit a little north 

 of Mazatlan within the mouth of the Gulf of California in latitude 

 24 38' N. The parallel of 25 N. latitude, as indicated in Drude's 

 Atlas, probably represents the extreme northern limit, which is 

 thus five or six degrees north of the latitude of the large island 

 of Hawaii. 



