CHAPTER XIV 



THE RELATION BETWEEN LITTORAL AND INLAND PLANTS 



Professor Schimper's views. Great antiquity of the mangrove-formation. 

 Problem mainly concerned with the derivation of inland from littoral plants. 

 Grouping of the genera possessing both coast and inland species. 

 Scaevola. Morinda. Calophyllum. Colubrina. Tacca. Vigna. 

 Premna. 



IN discussing the relation between the littoral and inland floras in 

 the Pacific it will be at first necessary to pick up some of the 

 threads of the various lines of investigation dealt with in the 

 previous portion of this work. Apart from considerations con- 

 nected with the genetic history of the plants concerned, when 

 we come to inquire into the sources of any individual strand-flora, 

 whether in the temperate or in the tropical regions, we arrive 

 at the rough and ready inference that it is composed of " what the 

 sea sends and the land lends." But it has been already shown 

 that the relative proportion of the current-borne and in con- 

 sequence widely dispersed plants in a strand-flora varies greatly 

 in different regions. Thus in the Pacific islands, as typified by 

 those of Fiji, about 90 per cent, have buoyant seeds or seed- 

 vessels originally brought from distant localities ; and in the 

 tropics, as a rule, the average would probably be never under 

 75 per cent. On the other hand, in a temperate region the plants 

 derived from inland would be most predominant, making up 

 probably some three-fourths of the whole, whilst the proportion of 

 current-dispersed plants hailing from distant places would be 

 relatively few. 



It is on this account that there is such uniformity in the 

 general composition of the strand-flora over a large part of the 

 tropics, since current-dispersed plants are widely spread. But in 

 the temperate regions we find a great contrast in this respect. 



