46 I'rucccdbujs of the Ohio State Academy of Science. 



later this is cliangetl to a rose mallow garden by the large rose- 

 colored bells of Hibiscus moscheutos. 



Associated with tliese dominant species is a large numljer of 

 plants, additions to which are made from year to year by the 

 successful ecesis of invaders from nearby regions. The second- 

 ary species of the marsh zone are in large part also the asso- 

 ciated species of at least the outer portion of the thicket associa- 

 tion, due to the invasion of the marsh by the shrub zone. Altho 

 in general the water level is not as high as in the marsh, the 

 surface is broken by innumerable small pools and depressions 

 between the clumps of ferns and roots of shrubs, and there the 

 marsh plants find sufficient water. 



Tlie most marked difiference between the two associations is 

 in the light exposure. In the deeper shade of the thicket many 

 of the marsh plants as Impatiens biflora and Triadenum virgin- 

 icum, tho numerous, are small and weak and do not blossom. 



The secondary species of the marsh association given in 

 general in the order of their abundance are as follows : 



Impatiens biflora is generally distributed thruout the forma- 

 tion. When growing in full light exposure at or very near the 

 water's edge, it is tall and vigorous and generally covered with 

 Cuscuta grono\ii which also gr()ws luxuriantly on Decodon. 

 Solanum dulcamara grows in detached masses over shrub's and 

 herbs or roots at the outer margin of the zone, the long branches 

 hanging down to the water. It is a very conspicuous j)lant in 

 the late summer and autumn with its numerous clusters of 

 bright-red berries. 



Three species of Bidens, Bidens cernua, B. discoidea and 

 B. frondosa grow at low water on the shelf of exposed peat. 

 Bidens cernua and B. discoidea grow even in shallow water. 

 In a remarkably short time after masses of peat have risen 

 above the surface, they are taken possession of by one or several 

 of these species of Bidens and the unsightly peat mass shortly 

 becomes a varitable carpet. Echinochloa walteri is frequenth' 

 associated with the Bidens. They take possession of every rot- 

 ting stump and log as soon as it comes above the surface. 



