238 ZDENEK CERNOHORSKY 



Scandinavian flora and to the bicentric distribution of some rare plants in the 

 Scandinavian mountains. Two facts are of the utmost importance: "Fossil 

 records indicate that conditions in South and Central Sweden were not 

 favorable for immigration from the south of much of this flora during the 

 deglaciation period. Other fossil records indicate that Arctic-Alpine plants 

 grew in the mountains immediately after deglaciation.'" By these facts, he 

 gives additional evidence for the survival of the present Arctic-Alpine flora 

 during the Last Glacial Age in refugia along the Scandinavian coast and 

 adjacent mountains. 



Among the Scandinavian lichens are also found West Arctic species, e.g. 

 the previously mentioned Agyrophora rigida (Du Rietz) Llano and Umbilicaria 

 havaasii Llano (Llano, 1950), and endemic types, e.g. Rhizocarpon superficiale 

 (Schaer.) Vain. ssp. spleudidiim (Malme) Runemark (Runemark, 1956), as 

 well as representatives of the bicentric distribution, e.g. Philophoron robustum 

 (Th. Fr.) Nyl. (Dahl, 1950). 



We have not mentioned, as yet, the epiphytic lichens. Degelius (1957) is 

 applying himself to the question of epiphytic lichens and their survival during 

 the Glacial Ages in Iceland. He points especially to ParmeVia aspera Mass. 

 Its habitats are situated near presumed refugia of vascular relict plants during 

 the Last Glaciation. At the same time this obligately epiphytic species has a 

 dominant place in the epiphytic vegetation of birch stands in Iceland (but not 

 in Scandinavia). It is known from Scandinavia, where it shows a wide ecologic 

 amplitude, and from North America, but not from Greenland. From these 

 facts, as well as from others, DegeHus presumes that it is a very old type, of 

 Interglacial or perhaps Preglacial age. Supporting this view is also the fact 

 that remnants of a birch closely related to recent forms growing in Iceland 

 have been found in Tertiary layers, and remains of a birch in an old Interglacial 

 layer have also been collected there. Dermatina major (Nyl.) Lettau may be of 

 the same age, too. Other epiphytic lichens of Iceland are probably younger, 

 some of them being introduced by man in recent times (e.g. Xanthoria 

 lobulata (Flk.) B. de Lesd.). 



In the above outline I have restricted myself to the probability of lichen 

 survival in refugia in the North Atlantic basin during the Last Glacial Age. 

 I did this mainly for the reason that we have no paleontological records of 

 lichens from earlier geological periods. In spite of this fact, it is evident from 

 this outline that the lichen flora in the described space includes various ele- 

 ments which of course are of a different age there. Various authors evaluate 

 differently the age of the same type, when even the same author rates the age 

 of a given type very vaguely. It can be said, in spite of this, that the oldest are 

 the Arctic-Alpine species with immense, but not continuous distribution 

 (i.e. showing great gaps) in the world. These species have persisted there 

 probably since the Tertiary age. What a pity that we do not know better the 

 distribution of Arctic-Alpine microMchens which undoubtedly survived 



