1 92 1. No. 7. STUDIES OX THE LICHEN FLORA OF NORWAY. 23 



Others. — But the distribution of our crustaceous lichens is not so well 

 known that we can build much upon them. 



Among the higher lichens we may first mention the alpine Gyrophora- 

 species, medium sized or large dark lichens, affixed to the substratum at 

 the centre, and free at the margin. A type species is the large and statel}' 

 Gyrophora Iciocarpa. It has hardly ever been found so far down as the 

 upper tree line, and it ascends to 2000 m. or more. Gyrophora fiiliginosa 

 and Gyrophora nigifcra are still more so high alpine. 



The GyropJwra species are saxicolous, but the mountain gravel heaths 

 also have a special lichen flora, e.g. the three Akcforia species: A.ochrolaica 

 and A. divergens, so plentiful on the southern mountains and A. nigricans, 

 which is more common in Northern Norway. 



There is a considerable difference between the southern and the 

 northern alpine flora in our country- with regard to the species represented 

 as well as to their relative frequency. We must not forget that the 

 distance between the southern Norwegian mountains and Eastern Finmark 

 is as great as the distance from London to southern Spain, or from Paris 

 to Messina. Gyrophora fiiliginosa is common on Langfjellene in Southern 

 Norway, but as yet it has not been brought home from Dovre or from 

 the mountains north of Do\Te. Cetraria nigricans is northern, common in 

 Lapland and the adjacent parts of Troms and Finmark, and never recorded 

 from Southern Norway. 



At places where the mountains are steep or near the sea, many 

 alpine plants extend to the plains, or even to the strand. In Western 

 Norway man}- typically alpine plants are found on the shore, carried down 

 by the rivers. It is more difficult to understand the presence of many 

 alpine lichens on the shore for their distribution cannot possibly be con- 

 nected with the ri\-ers. Thus Cetraria nivalis is quite common on sandy 

 strands at the Kristiania tjord and Cetraria norniorica Gunnerus (= C.tristis) 

 reaches down to the utmost skerries in Western Norway. It is not improbable 

 that they may be regarded as 'relics'. 



There are on the whole many points of resemblance between the 

 alpine and the strand lichen flora. This is perhaps due to the fact that 

 either of these stations offers large areas (rocks &.c) where lichens can live, 

 but which are too poor for other plants. Accordingly they both have an 

 important biological feature in common: that several species cover areas 

 of some extension; they form associations. The mountains as well as the 

 strand are therefore well suited for ecological lichen studies. 



4. Arctic maritime lichens. 



On the coast north of Lofoten and especially in Finmark we find a 

 characteristic and interesting lichen flora. 



The farther north we go the poorer are the conditions and the 

 smaller the plants. This is also the case with the lichens, and the most 



