194 



phytic and a planation called base level is approached. This planation 

 is interfered with by crustal movements. If the movement be upv^ard, 

 the mesophytic development of hills is retarded while that of the swamp 

 is hastened. A downward movement, on the other hand, would hasten 

 the mesophytic development of upland and retard that of the lowland. 

 From tliis, it will be seen that the ultimate tendency, at least in this 

 climate, is toward the mesophytic condition. Whether the change is slow 

 or rapid is determined by the locality in which it occurs. A granite hill 

 develops much more slowly than a morainic region lilie that about Winona 

 Labe. 



Here we have the "linob and liettle hole" lake and swamp of the termi- 

 nal moraine. The soil is that attendant upon such a region, a mixture of 

 sand, gravel and clay, with here and there a predominance of sand or clay, 

 the whole being varied by stretches of the mucli of the swamp and the 

 sand of the beach. 



There are probably three main types of vegetation— the hydrophytic or 

 semi-hydrophytic societies of lake and swamp, the xerophytic or semi- 

 xerophytic of tlie morainic uplands, and the mesophytic along the 

 streams. In reality we have various combinations of these types and the 

 different plant societies are not limited to the respective topographic forms 

 as indicated, since the region shows marked evidence of development 

 toward the climax type. 



1. The Lake.— There are all gradations in the "kettle hole" in the im- 

 mediate vicinity of Lake Winona, from the lake itself to the various un- 

 drained and half-drained swamps scattered here and there about the mar- 

 gin of the lake and representing old ponds which have gradually become 

 filled up by the encroachment of vegetation upon them. 



Where the vegetation in the lake is most luxuriant, we find, in the 

 outermost zone, Nymphaea odorata and Nuphar advena (the white and yel- 

 low water lilies); next, Pontederia cordata (pickerel weed), and nearer 

 the shore the bulrushes (Scirpus lacustris and Scirpus pungens). A num- 

 ber of species of Potamogetons are found among all of these, in some 

 places reaching far out into the lake. At the mouth of Chen-y Greek 

 Potamogeton fluitans predominates, with Potamogentons pectinatus, Pota- 

 mogeton zosteraefolius and one or two other species nearby, together with 

 Hydrophyllum (water milfoil) and Ceratophyllum (hornwort). In this so- 

 ciety Chara has a place by no means unimportant. It is especially promi- 

 nent in the northwest arm of the lake, which, in its luxuriant growth 



