I'.IO OLAF GAI.L0K 



Stereocaulon denudatum. podetia-*wandering f'ruticose lichen. 

 Sphserophorus fragilis. 



coralloides 

 Cetraria aculeata, 

 Cladonia pyxidala, hypothallus-wandering fruticose lichen. 



gracilis, 



cornucopioides, 



Cetraria islandica, erect foliaceous lichen. 

 Peltigera canina. procumbent foliaceous lichen. 



rufesceus, 



aphtosa, 



Solorina crocea, 



Pertusaria corallina. crustaceous lichen. 

 Sterile crustaceous lichens. 



Altogether about 18 species. Quantitively, as far as it appears, 

 the fruticose lichens are decidedly dominant in some places. Thus, 

 Jonsson has seen them in such abundance amongst Grimmid. 

 that he calls them "indicative of Lichen-heaths." But this appears 

 to be only true of patches here and there. I myself have not met 

 \vilh this phenomenon. In Denmark we have nothing that can be 

 compared with the Icelandic Grimmza-carpets, as regards superficial 

 extension. Where we, here and there, find Grimmia-bogs scattered 

 in our heaths, they are generally small, and appear to be wetter 

 at the bottom, than are those in Iceland, and are consequently 

 practically devoid of lichens. The difference no doubt chiefly de- 

 pends on the fact, that in Denmark the Grimmia-bogs usually occur 

 in damp hollows, where stagnant ground-water furnishes them with 

 the necessary moisture, whilst the Grzmmia-carpets in Iceland are, 

 in a higher degree, directly furnished with this by rain. The 

 C/r//mn/a-carpets in Denmark have, as a rule, undoubtedly a quicker 

 vertical growth, and deeper peat-substratum, which explains the 

 characteristic paucity of lichens in our Grun/nza-carpets, and the 

 lichen-wealth in those of Iceland. It is consequently, in the first 

 instance the competition which is stronger and more inimical to 

 lichens in Denmark than in Iceland. 



Besides this, it is strange that the Iceland <7r/ni/ma-carpets can 

 contain quantilively, such an abundance of crustaceous lichens, 

 whilst ours are quite devoid of them. 



A Table will render the difference plain: 



