1867.] DRUMMOND — DISTRIBUTION OF PLANTS. 175 



boreal in its aspect than that of the northern coasts of the former 



lake. 



It is a fact of considerable interest that far up the River St. 

 Lawrence, upon both sides, even towards Quebec, are found, 

 mingling with sub-arctic forms, some species of truly arctic range. 

 Rubus Chamcemorus Linn., Gentiana acuta Miehx. , Pleurogyne 

 rotata Linn., Empetrum nigrum Linn., and Woodsia hyperborea 

 R. Br.,* among others, range as far up the river bank as liiviere-du- 

 Loup, where they have been detected by Dr. Thomas ; and Astra- 

 galus alpinus Linn., A. secundus Michx., Vaccinium Vitis Idcea 

 Linn., V. uliginosum Linn., .Euphrasia officinalis Linn., with one 

 or two other boreal forms, extend to the Island of Orleans and 

 Quebec. In seeking for an explanation of this somewhat peculiar 

 diffusion, it must be borne in mind that arctic plants delight in 

 a low equable temperature, accompanied by a moist atmosphere, 

 and wherever these conditions exist, whether on mountain summits 

 or on northerly ocean coasts, there these little plants can find a 

 home. Now, the coasts of the Lower St. Lawrence amply supply 

 these conditions. They occupy a rather high latitude, and besides 

 frequently rise to considerable elevations, forming extensive cliffs. 

 The broad and deep expanse of water fronting them necessarily 

 has the effect of lowering and equalising the temperature, and the 

 evaporation, which must be very great, continuously taking place, 

 aided by the winds, moistens the surrounding air. Further, a 

 branch of the cold Labrador current flows through the Straits of 

 Bellisle, carrying with it, no doubt, amongst other drift, seeds of 

 arctic and sub-arctic species, and extends its influence far up the 

 St Lawrence. This current would further aid in lowering the 

 temperature of the immediate shores, but its effects, the more 

 marked because the waters are chilled by recent connection with 

 icebergs, would be especially experienced upon the island of Anti- 

 costi, which, from its position, w 7 ould intercept the current, and tend 

 to direct it towards the entrance of the river. To these causes 

 must be ascribed this climate which seems so suited to these little 

 arctic and sub-arctic species of the more eastern sections of the 

 Province. 



Upon the northern shores of Lake Superior some of these causes 

 likewise operate. There is the same moist atmosphere and more 



* Editor's Xote.— Woodsia hyperborea R. Br., has been found by Mr. 

 Horace Mann in north-western Vermont; //'. Ilvensis (Linn.) is abun- 

 dant on the rocks of the Quebec group south of the St. Lawrence. W. 



