248 



ROLF NORDHAGEN 



The sequence of Papaver taxa (in part with 2« = 70 chromosomes, and in 

 part with 2« = 56) (Fig. 6) occurring in Scandinavia from north to south, of 

 which the northernmost populations on the Varanger Peninsula and the 

 southernmost ones in the mountains of Valdres and Sogn have white latex, 

 whereas all the others have yellow latex, is so remarkable from a 

 phytogeographical point of view that it cannot possibly be explained as a 

 result of Late Glacial immigration with a consecutive species formation. Here 

 the ""tabula rasa''' theory Uterally crumbles. However, as I still do not consider 

 the problem of Papaver taxonomy and nomenclature finally settled, I do not 

 want to elaborate on it here. 



unlcenlric specleS' ./ ^y^ ' ...^ 



iri^: 



-i - f%<v." ;,•■• 



'F, 



V X--J.-- ■■:■■ 



e^^i«'«'...:rf^'>.-^. 





bicentric speciesj ^ ,j^^/,. X"^' — >^'/i5l^' < ~\ ' ' 



;^-"^??;''-"'^\-j? 





f Pi:#^ P#IP P4W ' 

 ^^--OV fe'^;-%^ fe^^ft^ '. 



Fig. 5. Examples of uni-and bicentric distribution of mountain plants in Norway 

 and Scandinavia (after Nordhagen, 1936). 



Fries (1921) made it clear that the Scandinavian mountain flora possesses 

 an endemic taxon, Euphrasia lapponica, belonging to the salisburgensis group 

 (Fig. 7). It is a bicentric species, absent between South Trondelag and the 

 Polar Circle. Hugo Dahlstedt, the late, famous'Swedish specialist on Hieracium 

 and Taraxacum, demonstrated in 1928 that Taraxacum Reichenbachii 

 Huter ssp. dovrense Dt. ought to be regarded as a species of its own, T. 

 dovrense Dt. It is found exclusively in the south Norwegian mountains from 

 Opdal in the north to Lom in the south. It is closely related to the extremely 

 rare T. Reichenbachii, a taxon of the Tirolian Alps east of the Brenner Pasa 



