76 Proceedings of the Ohio State Academy of Science. 



There are four distinct groups of vegetation units or as- 

 sociations based on habitat and growth forms : 

 I. The pond association 

 II. The shore association 



III. The swamp-shrub association 



IV. The mesophytic-forest association 



The first, second and fourth are well developed, the first 

 exhibits a striking lateral and vertical zonation, the third is 

 fragmentary, but it is of interest as an illustration of the in- 

 trusion and development of a zone between two previously ex- 

 isting ones. 



I. The pond association on the southeast : This consists 

 of an association of semi-aquatics with 



1. Nelumbo lutea society 



Principal species : 



Nelumbo lutea 

 Secondary species : 



Potamogeton pectinatus 

 lonchites 

 natans 

 Ceratophyllum demersum 

 Cladophora sp. 

 Spirogyra sp. 

 The society forms a zone 20-40 feet broad. At the outer 

 margin the water is 4-4.5 feet deep, at the inner about 8 inches. 

 In the deeper water is a pure Nelumbo lutea family ; in the 

 shallower, the other plants, especially Potamogeton pectinatus 

 and lonchites, are quite abundant. There is some evidence of 

 vertical zonation or layering; in the deeper water the Nelumbo 

 leaves float on the surface; and in the shallower rise 12 inches 

 above the surface. 



2. Nelumbo-Polygonum society 



Principal species : 

 Nelumbo lutea 

 Polygonum emersum 



