220 STUDIES, SCIENTIFIC AND SOCIAL chap. 



and other truly Arctic plants. Along with these were a 

 few American alpine types, such as Eriogonums, Castilleias, 

 and several composites. Near the summit of the moun- 

 tain there were alternate upward-sloping bands of loose 

 rock-debris and short turf, the latter gay with pretty 

 3^ellow flowers. On examination these were founds to 

 consist of a potentilla and a saxifrage, whose flowers, rest- 

 ing close on the ground, were so much alike in size, form, 

 and colour that at a short distance they appeared identical. 

 The intermixture of two very distinct species of flowers, 

 coloured and shaped alike and flowering at the same time, 

 is very uncommon, because it would interfere with regular 

 cross-fertilization by insects. In this high and exposed 

 situation, however, where the flowering season is very 

 short and insects very scarce, the combination of two 

 species of flowers may lead to a more conspicuous display, 

 and be more attractive to whatever insects may visit such 

 great altitudes ; while with plants of such distinct families, 

 the intermixture of the pollen would lead to no evil result, 

 since each would be totally inert on the stigma of a flower 

 of the other kind. The two species appear to be Saxifraga 

 clwysanilia and Potentilla dissecta. 



On a general summary of the plants noticed during this 

 excursion to one of the richest districts in the Rocky 

 Mountains, I find that they comprised no less than 

 20 British species, about 45 European, mostly high 

 Alpine or Arctic, and about 30 species which, though dis- 

 tinct, were allied to European types. There were thus a 

 total of 95 species, either identical with or allied to 

 European plants, while those which belonged to American 

 genera, or were most nearly allied to American species, 

 were about 30 in number. It thus appears that the 

 alpine flora of the Rocky Mountains is mainly identical 

 with that of the Arctic regions, and it is this identity which 

 leads to the occurrence of so many British species in this 

 remote district. In the review of the entire alpine 

 flora of the Rocky Mountains by Professor Asa Gray 

 and Sir Joseph Hooker, the number of species identical 

 with those of the Arctic regions is 102, and the distinct, 

 though often allied, species 81, while those that be- 



