1921. No. 7. 



STUDIES ON THE LICHEN FLORA OF NORWAY. 



nivalis ascend higher on the mountains, and they can live on a dryer soil, 

 either preferring these stations or driven to them by competition. 



If left untouched after pasture or harvesting a Cladonia alpvstris field 

 will tirst be covered with the quick grower, Stcreocauloii pasclialc, almost 

 always intermixed with it. The latter species can produce full-grown thalli 

 in 5 — 6 vears. After some time small round CI. alpcstris are seen in the 



Fig. I. Experimental field Dakteaucce near Karasjok, Finmark. Harvested 18. 6. 1914, since 

 untouched. Phot. 9. 8. 1920. Notice slow regeneration. Author phot. 



Stereocaulon tufts, and in the long run it will gain the upper hand and 

 cover the ground again. 



The rapidity of growth of CI. alpcstris is not known. It will 

 evidently to a large extent depend on the degree of moisture, and on the 

 conditions of soil and climate. The dates given by farmers and Lap- 

 landers vary from 10—40 years. In any case it grows extremely 

 slowly. Six years öfter harvesting by hand or implements every 'gap' 

 in the vegetation was still distinct and the fresh tips were only 

 5 — 10 mm. long. (Fig. i and 2.) 



The growth is evidently strictly apical. I have cut down li\ing thalli with 

 shears and there was no growth to be seen from the surface of the cuts. 



