ALPINE AND ARCTIC PLANTS 449 



tends as far as Greenland. The Alpine epilobium is one of the 

 few White Mountain plants that have attained the bad emi- 

 nence of being regarded as doubtful species. Gray notes as 

 the typical form, that with obtuse and nearly entire leaves, and 

 as a variety, that with acute and slightly toothed leaves, which 

 some other botanists seem to regard as distinct specifically. 

 Thus we find that this little plant has been induced to assume 

 a suspicious degree of variability ; yet it is strange that both 

 species or varieties are found growing together, as if the little 

 peculiarities in the form of the leaves were matters of indiffer- 

 ence, and not induced by any dire necessities in the struggle 

 for life. Facts of this kind are curious, and not easily explained 

 under the supposition either of specific unity or diversity. For 

 why should this plant vary without necessity ? and why should 

 two species so much alike be created for the same locality ? 

 Perhaps these two species or varieties, wandering from far 

 distant points of origin, have met here fortuitously, while the 

 lines of migration have been cut off by geological changes ; and 

 yet the points of difference are too constant to be removed, 

 even after the reason for them has disappeared. If this could 

 be proved, it would afford a strong reason for believing the 

 existence of a real specific diversity in these plants. 



I have said nothing of the grasses and sedges of these moun- 

 tains ; but one of them deserves a special notice. It is the 

 Alpine herd's grass (Phleum alpinum}, a humble relation of our 

 common herd's grass. This plant not only occurs on the 

 White Mountains, in Arctic America, in the Canadian Moun- 

 tajns, from the summit of Mount Albert, in Gaspe, to the 

 mountains of British Columbia, and on the hills of Scotland 

 and Scandinavia, but has been found on the Mexican Cordil- 

 lera and at the Straits of Magellan. The seeds of this grass 

 may perhaps be specially suited for transportation by water, as 

 well as by land. It is observed in Nova Scotia that when the 

 wide flats of mud deposited by the tides of the Bay of Fundy, 



