194 



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

 is interfered with by crustal movements. If the movement be upward, 

 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 this, 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 

 Lalie. 



Here we have the "knob and kettle hole" lake and swamp of the termi- 

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

 .sand, gi-avel and clay, with here and there a predominance of sand or clay, 

 the whole being varied by stretclies of the muck of the swamp and the 

 .sand of the beacli. 



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

 senii-hydropliytic societies of lake and swamp, the xerophytic or semi- 

 xerupliytic- of tlie morainic ui)lands, and the mesophytic along the 

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

 <litt'ereut 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. Tlie T.ake.— There are all gradations in the "kettle hole" in th« im- 

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

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

 gin of the lake and representing old i)onds which have gnidually become 

 tilled up by tlie encroachment of vegetation upon them. 



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

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

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

 tlie shore the bulrushes (Scirp\is lacustris and Sclriius pungens). A num- 

 ber of species of I'otamogetons are found among all of these, in some 

 places reaching far out into the lake. At tlie mouth of Clierry (Veek 

 I'otamogetoii fluitans predominates, with rotamogeiitons pectinatus, Pota- 

 niogeton zosteraefolius and one or two otlier species nearby, togetlier with 

 Ilydrophyllum (water milfoil) and Ceratophyllnni (liornwort). In this so- 

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

 nent in tlie nortlnvest arm of tlie lake, wliicli, in its luxuriant growth 



