CH. II THE FLORAS OF THE PACIFIC ISLANDS 13 



coast plants are found to be still afloat. In the results of this 

 experiment we see the work of the ages. There has been, in fact, 

 a great sorting process, during which Nature has " located " the 

 plants with buoyant seeds or seed-vessels at the sea-coast, placing 

 the others inland. This is the clue that we shall follow up during 

 many chapters of this book ; and having in this manner introduced 

 the reader to the subject, I will now refer to the general results of 

 my investigations in this direction in the Pacific Islands. 



In Fiji there are about eighty littoral plants out of a total of at 

 least 900 species of indigenous flowering plants, that is to say 

 about nine or ten per cent. (Note i), the littoral grasses and the 

 sedges being with one or two exceptions excluded. These shore 

 plants belong to the sandy beach and to the coast swamp, and 

 most of them are distributed over the tropical shores of the Indian 

 and Pacific Oceans, whilst not a few occur on the coasts of tropical 

 America. They form the characteristic plants of the coral atoll, 

 and many of them have long been known to be dispersed by the 

 currents. From the list given in Note 2 it will be seen that these 

 eighty species belong to about seventy genera. Nearly all of them 

 (95 per cent.) possess seeds or seed-vessels that float at first in 

 sea-water ; whilst three-fourths of them (75 per cent.) will float 

 unharmed for two months and usually much more, and several of 

 them will be found afloat after a year or more, being still capable 

 of reproducing the plant (Note 3). 



The prevalence in the Fijian strand-flora of Leguminosai, 

 which are included in my list under the divisions Papilionaceae, 

 Cassalpinieae, and Mimoseae, is very significant. They make up 

 about 29 per cent, of the total. Excluding weeds and a few other 

 introduced plants, there are some fifty species known from the 

 Fijian Islands, and of these almost half belong to the littoral flora, 

 which as we have seen constitutes only a fraction (one-tenth) of the 

 whole flora. If we regard the genera, we find that out of some 

 thirty^Leguminous genera twenty are littoral and in most cases 

 exclusively so. This conspicuous feature in the constitution of the 

 strand-flora is of prime importance as concerns the question of 

 adaptation to dispersal by currents, since nearly all the Leguminosae 

 with buoyant seeds offer themselves as defiant exceptions to any 

 such law. 



I will now contrast the Fijian inland flora with that of the 

 coast from the point of view of the buoyancy of the seed or fruit, 

 according as it presented itself for possible dispersal by currents. 

 Rather over a hundred plants were experimented upon (Note 4). 



