476 



BOTANY OP LAKE HURON. 



Stellaria borealis. 

 Polygala paucifolia. 

 Lathja-us ocliroleucus. 

 Poteutilla auserina. 

 P. Norregica. 

 Epilobiiim pahistre. 

 Hippuris vulgaris. 

 Eibes rubnim. 

 R. laciistre. 

 Corniis stolonifera. 

 Liuurea borealis. 

 Louicera cffirnlea. 

 Galium boreale. 

 Solidago Houglitonii. 

 Aster borealis. 

 Tanacetum Hiironense. 

 Ai-temisia Canadensis. 

 Cirsiiim imdulatum. 

 Hieracium Canadense. 

 Nabalus racemosns. 

 Alopecnrus aristnlatus. 

 Oalamogrostis stricta. 

 C. Canadensis. 

 Cinna arundinacea. 

 Grapbepliorum milicoides. 

 Glyceria aquatica. 



Pyrola seciuida. 

 Moneses nniilora. 

 Prirmila Mistassinica, 

 Physalis granditlora. 

 Helenia deflexa. 

 Riiniex salicifolia. 

 Platanthera orbiculata, 

 P. obtiisata. 

 P. byperborea. 

 P. dilatata. 



Allium Schocnoprasum, 

 Tofieldia glutinosa. 

 Scirpus sjdvaticus. 

 S. cfespitosns. 

 Carex tiexilis. 

 0. lenticularis, 

 C. gynocrates. 

 C. scirpoidea. 

 0. Buxbaiimia. 

 C. Monosperma. 

 Thiticum repens. 

 Aspidinm lonchites. 

 Aspleninm ^^I'ide. 

 Cetraria Icelandica. 

 Cotoscopinm nigratinm, 

 Selaginella selaginoides. 



Many of the above-named species are confined to tlie Bruce Penm- 

 sula, and are apparently southern waifs from the more northern sub- 

 arctic vegetation of the Lake Superior region, encouraged hither by 

 a damp climate, a low temperature, and a great i-adiation of heat and 

 moisture. These interesting wanderei-s suggest many reflections, of 

 which the most attractive is that relating to the common origin, 

 subsequent dispersion, and final segregation in the tempei-ate regions 

 of the northern and southern hemispheres, of many of the forms 

 above enximerated. Of their birth-places as species, nothing is yet 

 definitely known ; whilst to account for their dispersion and segre- 

 gation, only one theory has been advanced that is at the same time 

 tenable and probable. We allude to Mr. Darwin's famous hyjDothesis 

 which assumes that these and other boreal types were driven from 

 our temperate latitudes into the Torrid Zone diu'ing the cold of the 

 Glacial Epoch, and, on the return of warmth, retreated in opposite 

 directions back towards the Poles, ascending to the Alpine summits 

 •of the mountains that crossed their line of march. This is not the 



