70 



differing from the blind islands only because of their distance be- 

 low the surface of the water. These bars are the favorite fishing 

 grounds in the lake. The resemblance of the Blind Islands to' 

 the summits of the hills in the lowlands which bore the same re- 

 lation to the former Greater Lake Ontario, shows at once that the 

 old lake must have been full of blind islands. Islands of the 

 same character exist near the outlet of Lake Ontario and on the 

 north shore but none on the south shore. 



One of the striking features of plant distribution is the com- 

 mon fact that some species of plants are widely and continuously 

 disseminated, while others occur only in remote and limited 

 localities. The latter are often designated rare species. In some 

 cases species are rare in one region and abundant in another, so 

 it may not be undesirable to use the expression in our title to 

 designate the well-known condition where plants are confined to 

 small areas. Plants of this description fall into three groups : 



1. Plants of recent introduction. 



2. Plants requiring peculiar conditions. 



3. Plants with no apparent cause for limited range. 



Plants of Recent Introduction. — Plants are localized upon 

 their introduction into new regions. The rapidity with which 

 they spread depends largely upon the capacity of the plant to 

 spread by seed dissemination or otherwise. 



Three species introduced into the region under discussion 

 illustrate this very well. 



Hyoscyaimis has been known to occur on the fort grounds in 

 Oswego for many years. It has not gotten beyond their limits 

 yet. 



Eryfhrea Ccntauriuin was introduced at Oswego, how long 

 ago, no one knows ; some have surmised as early as the French 

 domination of Canada. In 1880 it had spread into every neigh- 

 borhood within a radius of ten miles, and it may now be found 

 even twenty miles from the city. Beyond these limits it is not 

 known in central New York, 



In 1888 a few limited localities for Hicraciuui atirantiaaiui 

 were known in Oswego Co. It seems to have been there as early 

 as in any place in the state. Now it is everywhere, and is beyond 

 doubt one of the most pernicious and persistent weeds in the state. 



