276 RIKARD STERNER 



Quite in the definition of the continental element in the European flora (p. 229), 

 it was pointed out that the said element does not by any means form any 

 sharply defined part; numerous species form even series of transition to other 

 elements of distribution. In investigations of the South Swedish flora the se- 

 parate position of the continental element is even less prominent. With regard 

 to both their mode of occurring and their distribution, continental species often 

 may coincide with species with a different general distribution. 



Hence the distinguishing of the continental species in the South Swedish flora 

 would often seem rather artificial. It would seem particularly unnatural to se- 

 parate the Pontic steppe species possessing advanced outposts in South Sweden, 

 from the South or Central European xerothermous species that occur there in a 

 very similar way. South or Central European species of this type are, for in- 

 stance: Anacamptis pyramidalis (Oland and Gotland, in dry meadows), Anthericum 

 liliago (on the sandfields of eastern Skane, in Blekinge [one locality], on the 

 Alvar of Oland), Fumana vulgaris (Oland and Gotland on the Alvar), Globularia 

 vulgaris (Oland and Gotland on the Alvar), Helianthemum »canum Baumg.» 

 and oelandicum (on the Alvar of Oland), Orchis ustulata (dry meadows of Oland 

 and Gotland, in Skane, Blekinge [and in the Stockholm coastal skerries?]) and 

 militaris (like the former, but not in the Stockholm archipelago), Thalictrum majus 

 (Gotland and the coastal skerries of Ostergotland), Viola alba (Oland at Borgholm 

 in dry shrubberies), Lathyrus sphaericus (Skane: KuUen and in one locality in 

 S. Bohuslan). 



The ecology of similar species may, of course, coincide with that of the steppe 

 species, just as there are in several tracts steppe-like geographical conditions in 

 South and Central Europe. An examination of the distribution of the South and 

 Central European xerothermous species in South Sweden must thus give about 

 the same result as an examination of those of the steppe species. 



The limitation of the number of species treated in this study (such a limitation 

 was necessary for practical reasons also), however, is in full agreement with the 

 problem of this investigation, viz. what is the mode of occurring and distribution 

 in South Sweden of the South Swedish species that are widely spread in conti- 

 nental Eastern Europe? In other words, the enquiry does not concern species 

 of a certain ecological character, of which moreover we can know only very little, 

 but species with certain common character in the matter of their general distri- 

 bution, to which, in many cases at least, an ecological feature may be added, 

 but at the same time also other features that are important from a chorological 

 point of view, for instance the history of the distribution of the species. 



