158 OHIO’ STATE ACADEMY OF SCIENCE. 
the life of an aquatic crown-former. The Decodon zone is almost 
entirely wanting at the south end of the lake, having been 
recently destroyed as stated before. It was very perfect here 
formerly, as appears in Fig. 1, and at the south-east it is still 
very wide. On the west side the zone is rather narrow, being 
only abont fifteen feet wide. 
Other plants in this zone are: 
Alisma plantago L. - Ranunculus abortivus L, 
Sagittaria latifolia Willd Roripa hispida (Desv.) Britt. 
Scirpus lacustris L. Naumbergia thyrsiflora (L.) Duby. 
Carex comosa Boott. Cicuta bulbifera L. 
Iris versicolor L,. Cephalanthus occidentalis L. 
The Cephalanthus is here and there an invader from the out- 
side and will finally establish a new shrub zone because of the 
changed conditions produced by cultivation of the surrounding 
hillsides. | Had the lake remained in its natural condition sur- 
rounded by dense forest the progress of the zones would probably 
have been gradual and continuous, but as it is there will be from 
time to time comparatively sudden advances, thus producing con- 
fusion in the established order of the old societies. 
Unicinous ZONE. The distinctive peculiarity of this zone 
is the presence of various species of Carex, Eleocharis and Scirpus, 
together with Equisetum fluviatile L., which is very abundant in 
some places. Besides these there are a number of other moisture 
and mud-loving species. This zone is intercalated on the east 
and west sides where wide mud flats have been formed between 
the Decodon and shrub zoncs. It is very prominent on the east 
side where there has been much filling in from the cultivated 
field beyond. The zone is absent at the north where there has 
been no such filling and was probably also absent from the south 
end when natural conditions still prevailed. In the moister parts 
the Equisetum, Eleocharis and Scirpus are characteristic, while 
in the outer, dryer margin the various species of Carex form a 
thick sod in which occur a number of uliginous herbs. Some 
isolated pioneers among the shrubs, especially Cephalanthus, 
have also taken a foothold on the east side although still few 
in numbers. On the west side the zone has been much invaded 
and is now in a transition state, progressing rapidly toward 
a thicket and forest society. 
