Clare Island Survey — Phanerogamic/,. 10 89 



Potamogeton perfoliatus, Carex remota) ; plants with plumed seeds adapted 

 for air-carriage [Epilobium hirsutum, Crepis paludosa, Salix caprea, Typha 

 latifolia) ; powder-seeded plants [Erophila vulgaris, Sagina apetala, Habenaria 

 bifolia, Equisetum sylvaticum) ; plants with seeds which may be distributed by 

 being eaten by birds {Rubus Idaeus, Rosa tomentosa, Viburnum Opulus) ; or 

 by adhering to their feet or feathers (Geum urbanum, Epilobium hirsutum, 

 Asperula odorata, Bidens cernua, Typha latifolia, and the powder-seeded 

 species). 



Another argument which may be used against the introduction of the 

 flora of Clare Island or of the adjoining islands across water, or indeed across 

 any barrier, is the fact that the flora of all of these islands is actually richer 

 than that of most, if not all, equal areas of the adjoining mainland. Had the 

 flora any difficulty to encounter in its passage to the islands, we should 

 undoubtedly expect it to be reduced in variety. The comparative richness of 

 the island floras is the result of the greater variety of conditions prevailing 

 there. It seems, however, probable that the mainland flora was as rich as, or 

 more likely richer than, that of the islands before the period of the main 

 growth of the bogs. I would suggest that the vast blanket of peat which is 

 spread over so much of the mainland locally exterminated many plants there ; 

 while on the islands, where peat never formed to so great an extent, these 

 species have survived. 



The doubtful factor as regards the migration of the flora is the question of 

 the practical efficacy of "accidental" means of dispersal. These have been 

 discussed tolerably fully above ; and they do not seem to me, in this case, to 

 offer sufficient chances for the arrival of the large proportion of the flora 

 which, in the present state of our knowledge, we should have to put down to 

 their account. I am therefore inclined to think that overland migration is 

 accountable for the introduction of the bulk of the flora. The zoological and 

 geological evidence bearing on this point is discussed elsewhere by other 

 writers. 



Within the last few years the results of two important investigations 

 respecting the origin of island floras, one in our own latitudes and one in the 

 Tropics, have been published. Both are suggestive in connexion with the 

 smaller investigation dealt with in these pages ; and it may be permissible to 

 refer to them. 



The Case of the Faeroes. 



The case of the Faeroes is an interesting one, and one which appeals to 

 us, since the flora approximates to that of the northern portion of our own 

 islands. This island-group lies about 180 miles W.N.W. of the Shetlands, 



R.I. A. PBOC, VOL. XXXI. M 10 



