CHAPTER VIII 



THE LITTORAL PLANTS AND THE CURRENTS OF THE PACIFIC 



The working value of the currents as plant-dispersers. — The relation between 

 the currents and the distribution of shore-plants. — The clue afforded by 

 the American plants. — Two regions of tropical shore-plants, the American 

 and the Asiatic. — America, the home of the cosmopolitan tropical shore- 

 plants that are dispersed by the currents. — Hawaii and the currents. — 

 Summary. 



ACTIVE as the currents are in dispersing seeds and fruits over the 

 Pacific, it should be remembered that those plants that owe their 

 distribution to this agency are only shore-plants, and not, indeed, 

 all the shore-plants, but only those with buoyant seeds or fruits. 

 Even the coral atoll owes a great deal to the agency of the fruit- 

 pigeon and of other birds ; for instance, their species of Ficus, 

 Eugenia, and Pisonia. In order, therefore, not to form an ex- 

 aggerated notion of the efficacy of the currents, it will be necessary 

 to obtain some numerical idea of what they have really accom- 

 plished in transporting seeds and seedvessels over the oceans in a 

 state fit for successful germination on the shores upon which they 

 are stranded. It is requisite to make this proviso, because in some 

 cases the currents work to no purpose. Thus, the empty nuts of 

 Aleurites moluccana are carried far and wide over the Indian and 

 Pacific Oceans, and are stranded on the beaches of the various 

 islands, as I have found myself in the cases of Keeling Atoll, Java, 

 and Fiji. The Coco-de-Mer, or the Double Coco-nut Palm, is 

 another apt instance. Though its fruits have been carried far and 

 wide over the Indian Ocean, the species is restricted to the Sey- 

 chelles. So also the acorns of various species of Quercus are 

 widely but ineffectually distributed by the currents both in tem- 

 perate and tropical regions. (This subject oi useless dispersal is 

 dealt with in Chapter XIII.) 



