310 



RIKARD STERNER 



Sea-shore hillsides. In view of 

 the high demands for hght on the 

 part of steppe species, hillsides on 

 the sea-shores, sloping down to- 

 wards the water, ought to offer the 

 species fairly good habitats in a 

 natural vegetation. In the fskdr- 

 gdrd» (coastal skerries) of South 

 Sweden, therefore, there should be 

 numerous occurences of steppe spe- 

 cies. This, however, is by no 

 means the case. On the contrary, 

 the absence or inconsiderable occur- 

 rence of the steppe flora on coasts 

 is an almost universal feature of 

 the distribution of species in South 

 Sweden. An important cause of 

 this seems to be the fact that suitable 

 localities for most species are lack- 

 ing, thanks to the nature of the 

 ground in the rocky archipelagoes, 

 especially if the rocks are non-cal- 

 careous, as for instance in the 

 skdrgdrd o{ T]ust. Perhaps, too, the 

 climate may be of a certain impor- 

 tance. The steppe species are ge- 

 nerally strongly thermophilous, and 

 such should especially be the case 

 in South Sweden, where they are 

 generally quite close to their northern or north-western limits. In the exterior 

 part of the south-eastern coast of Sweden the temperatures are much less con- 

 tinental than some distance further inland. As it to some extent is shown by 

 the isotherm maps on p. 256 the coasts have during spring and early summer a 

 lower monthly average than the interior\ If the average of the daily maximum, 

 temperature is considered, the difference naturally grows still greater. The re- 

 markably scanty precipitation on the south-eastern coast of Sweden that might 

 be supposed to favour steppe species is counterbalanced by the lower saturation 

 deficit in the dampness of the air. 



f'g- 7- The distribution of Veronica spicata in the 

 Scandinavian North. 

 O: uncertain occurrences; cf. Plate i6. 



^ It should be observed, however, that, during the height of summer and in autumn, the daily mean 

 temperature and the average minimum temperature are higher on the coast than in the interior. 



