XVIII THE LEGUMINOS^ OF THE PACIFIC ISLANDS 201 



alluded to in these pages. Here we have a plant, the seeds of 

 which are known to be transported unharmed by currents all round 

 the tropics. Yet it is absent from Hawaii and from almost all of 

 the islands of Eastern Polynesia. In many cases an endeavour has 

 been made in this work to explain these difficulties. But the order 

 in the Pacific teems with such difficulties. We may ask with 

 astonishment why it is that the genera, and sometimes even the 

 separate species, of the Leguminosae seem so often to follow in 

 each case a principle of their own. 



Plants of this order in the Pacific conform to no one rule of 

 dispersal or distribution, whether we regard a species, a genus, or 

 the whole order. Take, for instance, the presence in Hawaii of 

 Canavalia galeata, a plant that, as we know it now could not 

 possibly have reached there through the agency of the currents, 

 and the absence from the same group of Entada scandens that could 

 have been readily transported there by the currents from America. 

 Or, if we take the whole order and look at the structures connected 

 with the buoyancy of the seeds, we find two types of structure and 

 the elements of a third. Then, again, whilst most littoral plants 

 with buoyant seeds retain the buoyancy of their seeds when they 

 extend inland. Leguminous shore-plants, like Afzelia bijuga and 

 Caesalpinia bonducella, when they extend inland in Fiji and Hawaii, 

 lose in great part or entirely the floating power of their seeds. 



Furthermore, most strand-plants, being typically xerophilous in 

 character, when they extend inland shun the forests and prefer the 

 dry soil and sparsely vegetated surface of the open plain ; but the 

 Leguminous genera and species (Mucuna, Afzelia, Entada, &c.) 

 when they leave the coast take to the forests, growing usually as 

 stout lianes, but sometimes as tall trees. Here again the Legu- 

 minosae seem to follow a principle of their own. As far as I know, 

 this is the only order in the Pacific pos.sessing forest-trees which, 

 as in the case of Afzelia bijuga in Fiji, are equally at home in the 

 woods of the interior and of the coast. 



Indeed, judging from Professor Schimper's observations, the 

 littoral Leguminosae of the tropics often display a physiological 

 constitution that seems in some respects out of touch with their 

 surroundings. They may, as in Sophora tomentosa and in Cana- 

 valia, present the xerophytic character of strand-plants, but fre- 

 quently they are not halophilous or " salt-loving," like other plants 

 associated with them on the same shore-station. They are often 

 shy of salt in their tissues, though able to thrive in salt-rich locali- 

 ties. That capacity which strand-plants usually possess of storing 



