PHYTOGEOGRAPHICAL CONNECTIONS OF THE 

 NORTH ATLANTIC 



Eric Hulten 

 Department of Botany, State Museum of Natural History, Stockholm 50, Sweden 



The present study is based on distributional maps of all plants known to 

 occur in Iceland, Greenland, Spitsbergen, Jan Mayen, Bear Island, and the 

 Faeroe Islands. The maps have been divided into 23 groups according to 

 their general geographical area : Circumpolar, European, American, Amphi- 

 Atlantic, and so on. 



The number of species belonging to each group and found in certain 

 localities distributed all over the map of the northern Atlantic have been 

 counted, and places with the same number of species in each category have 

 been united with Unes. In this way an idea has been gained as to how many 

 species of each group occur at different places. We find, for instance, how 

 many Circumpolar plants occur on Iceland or on Spitsbergen, and how many 

 species with their main area in continental Europe exist on these islands. The 

 maps should give a good idea of the relationship of the floras of the above- 

 mentioned Atlantic islands to each other as well as to adjacent continental 

 Europe and America. 



To each map has been added a sketch of the world range of all species 

 belonging to the group in question. As these ranges are very variable in 

 different species, these sketches can only give a general idea of their distribu- 

 tion. However, the sketches will help make the conditions understandable. 



Of fundamental importance for the phytogeography of the North Atlantic 

 is the question as to whether the species are native or introduced. Com- 

 munication between Iceland, Europe, Greenland, and America has been 

 intense and has been going on for several centuries. Very many weeds, or 

 plants otherwise not native, have been added to the natural floras. It is 

 desirable to exclude them from this discussion as they do not concern the 

 older history of the flora. About 210 such species, recognized by most 

 botanists as not belonging to the native flora, occur within the area ; most of 

 them are of European origin, and only about ten are American. 



In Iceland, Greenland, and Newfoundland, however, there are European 

 species considered native by botanists dealing with the respective floras, but 

 whose character suggests that they possibly have been originally introduced. 

 They occur in the natural vegetation, but this is hardly a rehable indication 



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