100 OLAF 1. RONNING 



Svalbard flora about 12 species belong to the group called bicentric in the 

 sense of Scandinavian botanists, i.e. they occur in both of the above-mentioned 

 areas. Here we mention only: Luziila arctica, Carex parallela, Sagina caes- 

 pitosa, Draba nivalis, Saxifraga hieraciifolia. Campanula uniflora, and others. 

 Plants distributed only within the northern one of the two Scandinavian areas 

 are represented in Svalbard by a larger number, i.e. about 20 species; Cassiope 

 tetragona, Hierochloe alpina, Papaver dahlianwn, Erigeron imalaschkense and 

 others are examples belonging to this group. 



The plants mentioned above have gaps in their distribution areas either 

 from southern to northern Scandinavia and then to Svalbard or from 

 northern Scandinavia to Svalbard. We have, however, among the Arctic- 

 Alpine plants one small, but distinct, group comprising only three species, 

 Draba gredinii, Kobresia simpliciuscula, and Phippsia concinna, which have an 

 even larger gap in their distribution, stretching from southern Scandinavia to 

 Svalbard. In a way, these latter might also be called bicentric, but with a gap 

 between their areas 600-800 km larger than that of the other group of 

 bicentric plants. The distance between their centers is about 1600-1800 km. 

 One of the three species, viz. Phippsia concinna, is also known from Bear 

 Island. We may therefore say that we know three groups of Arctic-Alpine 

 plants which are (a) common to southern Scandinavia and Svalbard, (b) 

 common to northern Scandinavia and Svalbard, and (c) common to both 

 southern and northern Scandinavia and Svalbard, but with a gap between 

 each center. For a fourth group we may place the ubiquitous Scandinavian 

 species, common also in Svalbard. 



On the whole, we may say that the Scandinavian centric species constitute 

 the phytogeographically most important group in Svalbard as well, and it 

 should be noted that it comprises a great part of the flora there. If these 

 plants survived the last glaciations in Scandinavia, we are led to the assump- 

 tion that there must have been chances for a third center farther north in ihe 

 Arctic, with conditions suitable for a possible survival of plants. This leads us 

 also to conclude that a possible connection between the flora of Svalbard and 

 Scandinavia must have existed before the Last Glaciation or even in Early 

 Pleistocene. 



Within the flora of Svalbard proper, plants can be grouped according to 

 their distribution. The southernmost part of Svalbard, Bear Island, has a few 

 plants known from northern Scandinavia, but not occurring farther north in 

 Svalbard. They are: Cerastium cerastoides, Hippuris vulgaris, Luzula arcuata, 

 and Stellaria calycantha. 



In the southernmost parts of the island of West Spitsbergen in the Spits- 

 bergen Archipelago are found two species which are isolated in this area. 

 They are : Salix herbacea and Ranunculus glacialis, and are known only from a 

 few isolated localities. One of them, viz. Salix herbacea, occurs also on Bear 

 Island. According to my opinion, this southernmost area of the Spitsbergen 



