10 



Nr. :\. (.. M. Ostknfkld: 



friends wiii' i'or soine years hillerly hoslile towards each 



OllUT. 



Siiice llu'ii, llu" (jueslion lias l)een sullVri'd lo lit- in 

 al)c'v;uu-e, ns botanists have realised llial Ijclore anything 

 new foiild hc said, it would he necessary to kiiow niucli 

 more aboiil the ilora ol" llic \\ hole ol" (ireenUuid and adjaceiil 

 countries. It may be ineiilioned, however, (hal L. Koi.dkrup 

 RosKNViNGE (1897) dealing wilh the vegetation ol South 

 (Ireenland, mentions the Norse colonisation as of importance 

 lo the coniiiosilion of the Ilora. 



In lUl.'i, the Swedish botanist H. G. Simmons i)ul)lished 

 an important paper on the phytogeography of the Arctic- 

 American archipelago, al the end of which hv also touches 

 on the question of Greenland's Ilora, and agrees with 

 Nathorst in regarding it as mainly post-glacial; on the 

 other hånd, he sides with Warming in considering it as 

 chielly Arctic-American. 



M. P. Porsild (1921) in a brief survey, follows Simmons 

 and Nathorst in assuming that the entire Ilora of Green- 

 land must have immigrated in post-glacial times. As regards 

 the routes of this immigration, he points out that part must 

 have come from the north-west via Smith Sound, and some 

 few from the north-east. Possibly this first immigration 

 route may have been of grcat(M- importance Ihan would at 

 first he supposed, as the post-glacial heat maximum recently 

 found (see p. 47) may have rendered this route j)racticable 

 for species which cannot now exist so far to the north. 

 He emphasises the importance of the ancienl Norse colo- 

 nisation in regard to the immigration of the southern forms 

 in South Greenland, bul j)oints out al Ihe saiue time that 

 various soulhcni species of American origin cannol have 

 come in by this means; they must have been brought 



