From the I'im.i.eiin of thb Torrey Botanical Club, 41 : 89-103. 23 Mr 1914.] 



Phytogeographical notes on the Rocky Mountain region 

 II. Origin of the alpine flora ::: 



P. A. Rydberg 



When studying the flora of a certain region or district, one 

 naturally asks himself the following questions: What is the origin 

 of these plants? Where did they come from? How did they 

 come there? W T here else are they found? Why are they found 

 there and not in adjacent territory? Why are they there and not 

 in other similar regions? Why are other plants found in similar 

 regions and not there? Many other similar questions might be 

 asked and none of them could be satisfactorily answered. We 

 can only make suggestions and surmises. Some answers may 

 seem satisfactory to us now, as others may have seemed satisfac- 

 tory to generations gone by ; others may seem merely probable, 

 and still others not even so. The alpine regions of the Rockies are 

 merely small isolated spots, when the whole mountain range is con- 

 sidered. They can be compared with a number of small islands, 

 now surrounded (so far as many of the species are concerned) by 

 barriers insurmountable, more so even than islands in an ocean 

 could ever be. It is far easier to tell what an alpine plant is (and 

 I have already in a former paper tried to give a definition thereof) 

 than to tell how it came there. If we had only endemic species to 

 deal with, we should perhaps explain its existence by a spontaneous 

 generation or as something originated from a related species, which 

 exists or has existed in the subalpine region below. The belief in 

 a spontaneous generation, at least so far as the higher plants or 

 animals are concerned, is now generally discarded. The deriva- 

 tion from related species of the subalpine region is in many cases 

 a satisfactory explanation of the existence of many endemic alpine 

 species but not of all. But how shall we explain the existence of 

 the same plant in the alpine regions of Colorado and the Alps in 



* In this paper the sedges have been omitted, as they have not yet been worked 

 up. Without an authentic determination of the species, it is risky to discuss such a 

 critical genus as Carex in a phytogeographical paper. 



89 



