I92I. No. 7- STUDIES OX THE LICHEN FLORA OF NORWAY. I3 



INTRODUCTION. 



Ubiquitous lichens. 



In Norway, as in every other country of limited size, there are certain 

 lichens distributed throughout the whole country. No lichen is more com- 

 mon and general in Norway than Parmelia physodes. It is well adapted 

 to this distribution, for it can grow on almost ever}' substratum, from hard 

 rocks to old decayed wood, on mossy rocks and on the stems and twigs 

 of all our trees and shrubs. 



Paniiclia ompbalodes is almost as widespread, though not so abundant. 

 It is plentiful on the shore all round the country, common in the interior 

 and it is found at very high altitudes e-g. on the very summit of Haarteig- 

 nuten, (1700 m. s. m.l. 



We could mention some other ubiquitous lichens, e-g. a lichen of the 

 Cladonia silvatica tribus (Clado)iia mit is), which is plentiful in most parts 

 of our country up to very high altitudes; and also Lobaria scrobiculata. 

 The latter species is not high alpine and much less common than either 

 of the three above mentioned species, but it has been recorded from every 

 province in Norwa}-, up to the tree-line or somewhat higher. 



Ubiquitous are also some lichens wich require special conditions and 

 that are to be found everywhere in the country if their requirements for 

 living can be satisfied. For instance, some strand lichens, which are 

 equally general along our whole coast, from the Swedish frontier in the 

 south to the Finnish in the north (e. g. Rama Una aiigiistissima). 



There are also some ubiquitous crustaceous lichens. RJiizocarpon 

 gcogrophicum is general throughout the country. It is a widespread plant 

 throughout the entire world. 



I have never seen the apothecia of Ramalina ai/giis/issima, they are 

 rarely developed in Parmelia physodcs and Lobaria scrobiculata, and not 

 common in Parmelia omplialodes. With the exception of the latter species 

 we can leave the spores out of consideration for their distribution. The 

 3 first mentioned lichens are richly endowed with soredia. Other lichens 

 which are equally common within their range, such as Parmelia centrifnga, 

 have no soredia, buth they are usually fertile. The same is the case with 

 Rhizocarpon geograpliicinii. 



