1902] Fernald, — The Chilian Empetrum in New England 149 



Empetrum rubrum was described from the straits of Magellan and 

 though treated by Hooker as identical with the Chilian plant it was 

 maintained as varietally distinct by De Candolle. Judged by the 

 material of E. rubrum from the original region, Tierra del Fuego, 

 Hermite Island, and the Falkland Islands, De Candolle's course 

 seems the wisest, for the Fuegian and Falkland plant is far more 

 pubescent and has much coarser broader and flatter leaves than the 

 Chilian. The latter plant, however, var. andimim, De Candolle, as 

 represented by material from the Chilian Andes collected in 1854 by 

 Lechler and in i860 by Ochsenius has narrower leaves, and these 

 and the young branchlets, which are eventually glabrate, are at first 

 conspicuously tomentose as in the reddish-fruited plant of northern 

 New England and western Newfoundland. With such close identity 

 of characters and with no points by which the two plants can be dis- 

 tinguished the writer feels no hesitation in indentifying the pubescent- 

 branched and reddish-fruited Crowberry of New England with 

 Empetrum nigrum, var. andinum, DC, of the Chilian Andes. 



Upon first thought it seems very extraordinary that identical plants 

 should be found in such remote regions as New England and Chili, 

 especially when no intermediate stations are known. But many 

 similarly striking cases of isolated localities have been discussed in 

 the past. As long ago as 1859 Charles Darwin, extending Edward 

 Forbes's theory of a southern migration of northern types to include 

 transtropical migrations, called attention x to the presence at isolated 

 alpine stations in the South American Cordillera and as far south as 

 Tierra del Fuego of plants found in boreal North America and 

 Europe. The same point was more distinctly emphasized by Sir 

 Joseph Hooker in his splendid analyses of the distribution of arctic 

 plants.' 2 There he showed that of the 586 Arctic-scandinavian plants 

 recognized by him 40 are known in tropical America and 70 in tem- 

 perate South America. This remarkable isolation of northern Euro- 

 pean species in South America was accounted for by the natural path 

 for migration from the extreme North formed by the continuous chain 

 of the Cordillera of western America. During the intensely cold 

 periods preceding or accompanying the Glacial Epoch the plants of 

 northern origin and broad circumpolar distribution found in this 



1 Origin of Species, 373, etc. 



2 Trans. Linn. Soc. xxiii (1861), 251, etc. and in Jones, Man. Nat. Hist. Geol. 

 and Phys. of Greenl. 197, etc. 



