INTRODUCTION TO THE REPORTS ON INSULAR FLORAS. 47 



with in the earliest stage of such an insular flora are Portulaca, Sesuvium, Canavalia 

 obtusifolia, and Ipomcea biloba [Ipomcea pes-caprce) ; all of which seem to possess an 

 unlimited power of colonisation. Moreover, they provide the conditions necessary for 

 other plants to be able to establish themselves. Among the early shrubby occupants, 

 Suriana maritima, Pemphis acidula, Sccevola henigii, and Tournefortia argentea are 

 prominent, being found on the most remote islets of the Pacific and Indian Oceans, within 

 the tropical and subtropical zones. Where there are muddy shores, there the various 

 mangroves (Rhizophora, Bruguiera, Avicennia, Vitex, &c.) take possession. Among the 

 first real trees are, Heritiera littoralis, Hibiscus tiliaceus, and Barringtonia speciosa, 

 together with screw pines. After this nucleus of a flora has been formed, it is compara- 

 tively easy for other arrivals to establish themselves ; and every addition, in a measure, 

 helps to provide the conditions for a still more varied vegetation. It may be safely 

 assumed, therefore, that if oceanic currents and birds have not been the means of 

 dispersing a large number of species of plants, and it is not certain that they have not, 

 they are certainly the most important agents in stocking islands, for without their action 

 the numerous remote coral islands, at least, would still be utterly devoid of phanerogamic 

 vegetation, and consequently uninhabitable. 



Even such plants as epiphytic orchids may owe their presence in an island to the 

 action of the waves, as Mr Moseley observed of one in Little Ki Island (see Part III., p. 

 306) ; and in the Philippines he found a young sago-palm that had been washed up 

 growing vigorously just above the ordinary beach-line. Granting that such occurrences may 

 be comparatively rare, still the results in thousands of years might be very great. If an 

 epiphytic orchid survive a sea voyage, why not almost any other plant in the large 

 accumulations of vegetable drift that are carried out to sea by ordinary currents, and 

 driven hither and thither by extraordinary storms ? 



Broadly speaking, the more remote the island, the fewer and the commoner the species 

 that would be likely to reach it, and such we find to be the case. 



As a further example of a flora that owes its existence mainly, if not wholly, as far its 

 phanerogamic element is concerned at least, to oceanic currents and birds, the Bermudan 

 may be named. In Part I., p. 9, will be found a tabular view of the geographical 

 distribution of the vascular plants, probably indigenous, in the Bermudas. Assuming 

 that several of the plants which we have included as probably indigenous owe their 

 presence to the agency of man, there would still remain a considerable number to be 

 accounted for in other ways. We have attempted to classify them according to the most 

 probable means by which they may have reached the islands. ( )f course there are some 

 fruits and seeds adapted for transport in a variety of ways. There is one possible means by 

 which some of the plants may have reached the islands, concerning which, however, too 

 little is known for us to be able to judge of the extent it has operated, if at all. 

 Like other creatures, birds doubtless sometimes pass portions of their digestible food 



