98 



Proceedings of the Ohio State .-Icadeiuy of Science. 



exception of Cranberry and two smaller islands near the east 

 shore, the flora belongs to the present climatic conditions of the 

 region. That invasion and migration are rapid and where not 

 disturbed by man, successful, is shown almost everywhere in the 

 lake. After ecesis the normal succession of fixed aquatics by 

 marsh societies and these by shrub or, if adjacent to cultivated 

 field or pastures, by ruderal societies follows rapidly and surely. 

 The climax stage, the mesophytic forest, a remnant of the "Big 



Fig. 31. Exposed mat of peat at margin of Cranberry Island. 



Swamp" forest, forms almost everywhere a marginal fringe; 

 and readily extends into the new territory as soon as a suitable 

 habitat is provided. Alore than half, possibly three-fourths of the 

 lake is not too deep for the pioneers, Nelumbo lutea, Polygonum 

 emersum, Castalia tuberosa and Potamogeton lonchites, pectinatus 

 and natans to become established. Floating macroscopic plants 

 seem to have but little part in building up the flora. They are 

 present only in limited and local areas in sheltered situations and 

 shallow water where they have been preceded by fixed aquatics. 



