258 THE BOTANY OF CHKISTMAS ISLAND. 



obtained there, nor are we yet acquainted with the Miocene flora 

 of the neighbouring countries, so as to be able to suggest which 

 of the plants if any belong to that date. 



For the purposes of this paper I have classified the plants 

 found in the various islands which are considered to have been 

 always isolated from the mainland according to the methods by 

 which their seeds or fruits can be disseminated and conveyed 

 across a large tract of sea. 



In this way plants may be divided into seven classes, viz. 

 1. Sea-borne. 2, Bird or bat-borne, by the seeds being swallow- 

 ed by these animals and eventually deposited uninjured. 3. 

 Adhesive (the seeds or fruits being attached to their fur or 

 feathers and so conveyed). 4. Plumed seed. 5. Winged seed 

 or fruit. 6. Powder seed ; these last three being conveyed by 

 gales of wind : and 7. Weeds, plants dispersed accidentally or 

 more or less intentionally by man. There are some other 

 methods of dissemination on land which cannot come into play 

 in populating islands, such as dispersal by terrestrial animals, 

 and insects, and by streams or rivers, and these may be neglect- 

 ed though they may act in dispersing a plant (the seeds of 

 which have once been successfully landed) over the remainder 

 of the island. 



There are a certain number of plants often widely distri- 

 buted which are certainly disseminated by one of these seven 

 methods, but by which is at present doubtful. ' Such for instance 

 are the herbaceous Malvaceae and many grasses and sedges, and 

 again there are some plants which may reach these islands in 

 more ways than one. Portulaca obracea may be an example of 

 this. In some cases it appears to have been accidentally intro- 

 duced as a weed, while in others it apparently came by sea. 

 In this paper I class it as Sea-borne. 



The weeds of human introduction have been already dis- 

 cussed. It remains to deal with the six other classes. (1) 

 Sea-borne seeds or fruits. The larger Sea-borne seeds or fruits 

 are tolerably well known for the most part. They have often 

 some adaptation or modification for protection from, the action 

 of the sea water, as in the case of the strongly developed 

 bladder-]ike calyx of Hemandia which protects the seed 



Jour. Straits Branch 



