102 OLAF I. RONNING 



Other regions of Svalbard, but there is on the whole a striking difference 

 between the floras of these fjord districts and other parts of Svalbard, e.g. 

 the fjords farther south, Hornsound, etc., and the north and east coasts where 

 the floras are much poorer in species. Hadac (1944) found a total of 114 

 species in the Sassen area of the inner fjord districts. In my opinion the 

 reason for this peculiar distribution must be sought within the historical 

 factors, as these areas must have provided possibilities for a survival of plants 

 during the glaciation. If a migration from the south had taken place recently, 

 we should expect the plants instead to be distributed especially in the southern 

 parts of the Archipelago or scattered all over the area where suitable sub- 

 strata occur. 



ISOLATED SPECIES 



A remarkable, isolated occurrence is characteristic of the three species, 

 Carex capillan's, Euphrasia arctica and Sibbaldia prociimbens. During an 

 expedition in 1960. I visited some small hot springs situated near the head of 

 the Bockfjorden on the north coast of Spitsbergen. Here, the only locality for 

 these three species was close to the springs and nowhere outside the limited 

 area influenced by the heat from the soil. 



The occurrence of these three species, of which Euphrasia arctica is one of 

 only two annuals in the flora of Svalbard (the other being Koenigia islandica), 

 represents a phytogeographical problem of its own. The nearest locaHties of 

 the three species are in northern Norway, and a dispersal to that region by 

 long-distance transport of seeds cannot be accepted. 



In my opinion, the only way to explain the occurrence of these three species 

 is to regard them as remnants of a previously larger vegetation distributed 

 all over Spitsbergen. But as the climate deteriorated, these species survived 

 within the area influenced by the heat from the hot springs. This explanation 

 is supported by the fact that one of the species, Euphrasia arctica, is an annual, 

 and that the hot springs are situated not far from the area previously outlined 

 as a center of rare plants in Spitsbergen, i.e. the inner fjord districts north and 

 south of the large Isfjord. If we presume that this area in a previous epoch with 

 a lesser degree of glaciation had a much richer flora than today, and that the 

 three plant species mentioned also occupied that area, it will be easier to 

 understand how they still can occur in such an isolated locahty. The deteriora- 

 tion of the climatic conditions caused other less hardy plants to die out, but a 

 few species succeeded in surviving in this limited area. 



From the same point of view it will be possible to consider the existence on 

 Bear Island of the few plants mentioned as occurring there, but nowhere 

 else in Svalbard, viz. Cerastiwn cerastoides, Hippuris vulgaris and Stellaria 

 calycantha. These plants also must be regarded as remnants of a previous 

 flora extending continuously northwards to the Spitsbergen Archipelago. 

 At least tv» o of them, viz. Hippuris vulgaris and Stellaria calycantha, are not 



