THE AZORES 



399 



of the native flora are almost all of them European species; and, 

 as might be expected from what has been said above, they are least 

 evident with the plants of the woods and most pronounced amongst 

 those of the sea-border and of the ponds and lakes. 



The restrictions of most of the characteristic plants of the woods 

 to the Macaronesian islands, the extension of nearly all those of 

 the upland moors to Europe, and the common dispersion on both 

 sides of the Atlantic of the plants of the seashore and of the ponds 

 and lakes, illustrate a principle of wide application to insular floras — 

 a principle, however, that is often best exemplified in tropical regions. 

 The varying degrees of isolation thus implied reflect, as will be shown 

 later on, the differences in the histories of the dispersing agencies 

 in stocking with their plants the woods, the moors, the ponds and 

 lakes, and the seashores. The currents have been for ages unceas- 

 ingly at work, directly and indirectly, in carrying seeds from one 

 coast to another; and as a rule in tropical latitudes the specific 

 connections kept up between the shore floras of different regions 

 can be mainly ascribed to their influence. In a similar manner 

 migrant waterfowl have sustained the connections of the plants 

 of the river, the lake, and the pond, over great areas of the globe. 

 In a like fashion, though to a less extent, birds of the grouse family 

 have kept the plants of the mountain moors of distant regions in 

 touch with each other. On the other hand, the dispersing activities 

 of forest-frequenting birds, as far as oceanic islands are concerned, 

 have been more and more restricted in the course of ages. The bird 

 finally comes to stay, and both plant and bird differentiate together. 



The foregoing subject is dealt with in the penultimate chapter 

 of my book on Plant Dispersal ; but it is one, the importance of 

 which was long since recognised by Godman in his work on these 

 islands (p. 339). The principles involved have been unable to find 

 their full expression in the islands of the Azores by reason largely 

 of the lesser antiquity of those islands as compared with such an 

 ancient group as that of the Hawaiian Islands in mid-Pacific. There, 

 the impress of a far greater antiquity lies on the flora, and where 

 species have been differentiated in the Azores genera have been 

 developed in Hawaii. As shown in the work above named, it is 

 on the forested mountain slopes of the Hawaiian Islands that most 

 of the peculiar genera and peculiar species, both of plants and birds, 

 are to be found. Here the agencies of trans-oceanic dispersal have long 

 since ceased to act. A later suspension of these agencies is indicated 

 by the plants of the mountain moor, which are generically connected 

 with regions on both sides of the Pacific, but are usually specifically 

 distinct. Yet, unless within recent times, there has been no suspen- 

 sion in the activity of migrant waterfowl as seed-carriers to the 

 Hawaiian group, and as a result we find in the waters and at the 

 sides of ponds and rivers plants that are widely distributed over the 

 world. Lastly, there are the beaches, where, through the action 

 of the currents in the run of the ages, we find several of the littoral 

 plants characteristic of the tropical shores of Malaya, continental 

 Asia, Africa, and America. We thus perceive that the Azorean 

 and Hawaiian floras exhibit the same progressive scale of connections 

 with the outer world, which are least with the plants of the woods, 



