Phytogeographical notes on the Rocky Mountain region 
Il. 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? Where 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 
oe in the alpine regions of Colorado and the Alps i in 
* In this paper the sedges have been omitted, as they aes not yee been worked 
- Without an authentic determination of the species, it 1 is risky to discuss such a 
critical genus as Carex in a phytogeographical paper. 
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