academy op sc IENCE s.] CONCLUDING REMARKS. 43 



Chapter 6. 

 CONCLUDING REMARKS. 



Of the 170 species of vascular plants which I found in the Alpine region of the Rocky 

 Mountains in Colorado, 63 occur also in the Arctic region, and 31 of these are even circumpolar. 

 Of the remaining species, very nearly 100 are endemic to North America, and many of these are 

 endemic to these mountains. We have seen that the geographical distribution of a number of 

 the Arctic-Alpine types is quite extensive, covering many of the higher mountain ranges 

 throughout the Northern Hemisphere. Furthermore, we have seen that certain species inhabit 

 stations very remote from each other, still having reached the Arctic regions. 1 Would it be 

 natural to suppose that this enormous distribution south of the Arctic region was effected by 

 means of migration of these plants? Or shall we accept the hypothesis of Schouw: "Eadem 

 momenta cosmica easdem plantas diversis in locis produxisse"? The fact that the majority 

 of these species are Alpine, wherever they occur outside the Arctic region, and that they are 

 associated with more or less closely related species, seems to speak in favor of this hypothesis, 

 proposed by Schouw. The difficulty in explaining the possibility of the very fact that several 

 of these Arctic-Alpine species inhabit the Baikal Mountains, the south European Alps, and the 

 Rocky Mountains, with no intermediate stations, would thus be removed; and there are other 

 stations even much farther apart. 



As a contribution toward solving this question, I have in detail summarized the geographical 

 distribution of these Arctic-Alpine Rocky Mountain plants. And, furthermore, by describing 

 these types I have endeavored to demonstrate the numerous analogies that exist in the Alpine, 

 the Rocky Mountain Alpine flora, and the Arctic. We have seen that the association with 

 related species is common to several of these, wherever they occur; we have seen also the uni- 

 formity in vegetative structures possessed by these species in the Alpine and Arctic regions. 

 Moreover, I have attempted to show that the elements of the Alpine flora, endemic to these 

 mountains, correspond almost exactly with the Arctic so far as concerns the vegetative struc- 

 tures, and above all the method of vegetative reproduction and hibernation, some of the most 

 essential phases in the life of these plants. It is interesting to note that although the clima- 

 tologic conditions in the Alpine region are very different from those prevailing in the Arctic, the 

 plants which are able to thrive under both do not exhibit any marked deviation in structure, 

 which might have been caused by the rather considerable difference as to temperature, precipi- 

 tation, and light. Some modifications may be observed, however, but of diminutive impor- 

 tance; they may be classified as variations, and as such only. 



Thus it seems safe to conclude that most, if not all, of the circumpolar species originated 

 in the Arctic region. The other Arctic-Alpine species may have originated in the mountains 

 farther south, some on this continent, some others -in Europe or Asia, while some certain of 

 these may have become developed and distributed from several centers, very remote. 



1 Holm, Theo: Contributions to the morphology, synonymy, and geographical distribution of arctic plants. (Report of the Canadian 

 Arctic Exped. 1913-1918, Vol. V Ottawa, 1922.) 



