Arctic Plants: Geographical _Distnbution 65 b 



CHAPTER II. GEOGRAPHICAL DISTRIBUTION. 



By examining the geographical table (Table 1, pp. 68-75), in which I have 

 enumerated most of the species which were collected on the arctic shore of this 

 continent, we notice that this flora is actually a composition of two, which are 

 very distinct, viz.: a northern and a southern. 'Of these the northern will, by 

 a close analysis, soon prove to contain a large contingent from districts very 

 reniote and, although mainly northern, by no means to be restricted to these 

 regions. But we call the flora "northern" because the most conspicuous part of 

 its components represents the circumpolar flora. With regard to the southern 

 element, this we readily recognize as being principally derived from our own 

 flora, the components being either identical with American types, or at least 

 exhibiting a striking analogy with our native species. 



Such dual composition recurs in other arctic countries, marked to a greater 

 or lesser extent, very characteristic in Greenland, 'less so in Finmark and Lap- 

 land, Spitzbergen, etc., but quite distinct on the Siberian coast, judging from 

 the interesting and highly instructive sketches contributed by von Baer and 

 Kjellman. For even if the arctic Siberian flora is not so very distinct from the 

 circumpolar or the truly arctic flora, there are certain types which may 

 readily be recognized as being of southern origin. 



Of great interest is the fact that even on the "Barren Grounds" are species 

 which also are at home in more hospitable surroundings, the Alps of Switzer- 

 land, the Pyrenees, and the Himalayas. And the enormous distribution, ex- 

 hibited by some of these plants, may solve the problem as to the migration of 

 the ancestral, circumpolar species during the glacial epoch. But at the same time 

 such widely scattered distribution farther south -may lead to the acceptance 

 of the theory pronounced by Schouw who, with so very few words, but substanti- 

 ated by briUiant observations, explained the problem as "Eadem ' momenta 

 cosmica easdem plantas diversis in locis produxisse." ^ In other words, while 

 emigration and return of the arctic plants, so admirably discussed by Nathorst,^ 

 cannot be contested, there is nevertheless some difi&culty in realizing the fact 

 that some of these northern types have found their way to the mountains at 

 such enormous distance from the arctic region. 



Nevertheless, some of these difficulties have been removed by the many 

 important points which Nathorst has brought up, especially with reference to 

 the supposed composition and distribution of the former arctic flora, its migra- 

 tion to the south during the glacial epoch and, finally, its retreat when the ice ' 

 receded. It is, for instance, an indisputable fact that the Altai mountains 

 harbour a considerable element of the arctic flora besides which the vegetation 

 of these mountains shows an unusually large number of species common to other 

 mountains, though far remote. And the natural cause of this wide distribution 

 of the Altai flora is by Nathorst explained as depending on the favourable con- 

 ditions in these mountains during the glacial epoch. When the temperature 

 decreased, and the alpine element of the Altai flora was forced to descend to 

 the lowlands, the flora was then able to distribute itself over the lowlands of all 

 northern Asia. For, contrary to Europe, there was no inland ice to prevent its 

 distribution; the plants were enabled to spread as far north as the climatologic 

 conditions permitted. Moreover, the relatively northern situation of these 

 mountains was an important factor with regard to the migration of the plants to 

 the arctic region. 



' Schouw, J. F. Dissertatio de sedibus plantarum originariis. Havniae, 1816. 



2 Polarforskningens Bidrag till Forntidens Vaxtgeografi. (A . E. Nordenskiflld: Studier och Forsknin- 

 gar. Stockholm, 1883, p. 231.) 

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