Fic. 28. Climax Thuja consociation. In such situations the light is too 
low to permit the growth of tree seedlings other than the cedar. 
EE ea ciinncd sll cect 
eager oa ae eS irae: — _ 
my 
Fic. 29. Potamogeton consocies in Silver Lake. The chief species is 
Potamogeton americanus. Willows fringe the margin of the lake. 
