FLORA OF THE PACIFIC ISLANDS. 19 



Flora. — On the shores of nearly all the islands in our region are found a few 

 plants common to all tropical countries, and which are easily dispersed by currents. 

 They belong to the families Malvaceae, Convolvulaceae, Solanaceae and Leguminosse, 

 and are of little interest. This association of plants is often called the madreporic 

 flora. In the low islands of the Pacific there is little else for the botanist ; add the 

 ubiquitous pandanus, coconut and mangrove and the tale is told. In the high islands 

 the interesting and peculiar flora begins at the height of about 1200 feet, and it is this 

 flora that contains all the species peculiar to the islands. 



In the many shaded and moist valleys of Polynesia ferns find a congenial home, 

 and from the lightness of their spores are easily distributed; hence the Polynesian 

 flora presents 15% of ferns. Other predominant plants are provided with especially 

 light seeds as in the families Urticaceae, Rubiaceae, Lobeliaceae and Orchidacae. The 

 last family counts many species in Fiji and the Society Islands as well as in Australia, 

 while on the Hawaiian Group only three small species are found. On the other hand, of 

 the Lobeliaceae none are found in Fiji, three only in the Society Islands, while on the 

 Hawaiian Islands are found more than fifty species. Most of the Polynesian vegetation 

 is woody ; annuals form only 1%, and most of these are strangers confined to the shores. 



The question of the origin of the plants on isolated groups is of great interest, 

 but its discussion would carry us far beyond the limits of this introductory chapter. 

 It will be found, however, that the widely disseminated plants are either provided with 

 wings or other suitable appendages for the wind-borne journey, or are attractive food 

 for birds of passage. In the stomachs of pigeons killed in Micronesia have been found 

 the seeds of Fijian plants. The lantana (L. camara) was cultivated for years in gar- 

 dens in the Hawaiian Islands but it showed no tendency to spread until the so-called 

 mina ( Acridotheres tristis) was introduced, when the berry became its favorite food 

 and the indigestible seed was scattered everywhere. Cosmopolitan species are intro- 

 duced by winds and currents, hence a study of these will explain many cases. Rare 

 American plants are almost confined to the Hawaiian Group, the nearest to that con- 

 tinent and in the line of the NE. trade winds. 



Of the flowering plants the proportion to the whole flora is in south-eastern 

 Polynesia 20%; in Fiji, 40%; and in the Hawaiian Islands, 80%. The affinities of the 

 plants in each group are instructive. About 500 species are common to Asia and 

 tropical Australia. Some 220 species are common to New Zealand and Australia. 

 Of the two species of Ranunculus found on the Hawaiian Islands, one resembles 

 R. sericeus of Mauritius ; the other, R. repens of America. Fiji has one species each 

 of three Asiatic genera, Ternstrcemia, Saurauja and Furya. Hawaii and the Mar- 

 quesas have each a species of the distinctively American genus Waltheria. 



If we look rapidly at a few of the more important families we shall find that the 



Leguminosae are not common in Polynesia ; of the genus Acacia all the species peculiar 



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