The Botany of Iceland - 01.12.1930, Side 29

The Botany of Iceland - 01.12.1930, Side 29
STUDIES ON THE VEGETATION OF IGELAND 19 í'egions. For \ve cannot take it for granted that a species, because it has come to a certain region, will at once assume the most pro- nounced life form of the region in question. The dominating life form in arctic regions is Ch, yet we find species with another life form, and these species must be supposed to be just as well adapted to arctic regions as several of the chamaephytes growing there. Conversely, in regions having a liemicryptophyte climate, we may find Ch. A species like Calluna vulgaris must be assumed to be just as well adapted to the Danish climate as many hemicrypto- phytes. Even though Raunkiær’s life forms give an ex- cellent biological picture of the climate, they do not give the most accurate picture of it. The distribution of the species must rank first in this respect. However, there must be no disagreement between results obtained by means of Raunkiær’s life forms and those obtained by investigations based on the geographical distribution of the species, though at the outset we must expect the latter to give tlie more pronounced result. Raunkiær’s life forms picture the morphological adaptation of the spe- cies, the species groups give expression to tlieir physio- logical adaptation, both, however, express their adap- tation to the same life conditions. Various enquirers in various countries have at different times worked out a classiíication of the floras of their respective countries. Thus Watson divided the Brilish flora into groups according to the geographical distribution of the spécies. A. Blytt divided the Nor- wegian llora on a somewhat similar principle, and various Swedish enquirers, i. a. Gunnar Andersson and H. Hesselman, have clas- sified the Swedish flora. Ostenfeld has classified the ílora of the Faeroes, Porsild and Ostenfeld the Greenlandish ílora. The principle acted upon by all tiiese enquirers was to separate all spe- cies having a pronounced northern or southern distribution from all sucli as showed an equal distribution over the entire area. This resulted in the first instance in the setting up of three groups, while Watson and Blytt in addition classified the species according as they had a pronounced Atlantic or continental distribution. An attempt to bring together the species groups of the various autliors and thus arrive at a classification of the Icelandic flora proved impossible, since their species groups overlap to such a de- 2*
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The Botany of Iceland

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