201 



the base of the hills, on the teiisu)n line adjoining the swamp, is the 

 black hncklebeiT}', Gaylnssacia resinosa. (See bac-kground of Fig. 3.) 

 The oak stage has i-eqniredVo long a time to develop and has been in 

 existence so long that TreTiave only the result and little evidence of what 

 preceded this type. In the north the coniferous forest comes first. Clear- 

 ings give some intimation of the order of succession, and they are numer- 

 ous, thoiigh somewhat deceptive, as the stages in this case follow one 

 another much more i-apidly than tluw would in a virgin soil in which 



Fig. 5. View iif the channel and abutinent,< of the upper or lesser dam. From the con- 

 dition of the vegetation in the foreground, it is evident 5haf th« stream's gradient is small. 

 Upon the left and right the surface rises abruptly to 12 feet, and is covered with- heavy 

 mesophytic trees. The soil is sandy. This is a place where vegetation is capable of closing 

 the drainage lines. 



there had been no foundation laid for later types. Where the soil has 

 been cleared the first plants that follow, as shown on the north and west 

 sides of the lake?' aj'e Xerophytic annuals and perennials, such as poke 

 weed (Fhytolacca decandai, mullein lYerbascum thapsus). Canada thistle 

 (Cnicus arvensis), hounds-tongue (Cynoglossum officinale). Leonurus Car- 

 diaca. Arctium lappa, Echinospermum lappula. These seem to be fol- 

 lowed by elm and hickory. The beech-maple forest i^ working its way 

 in so slowly around Winona that at first glance there seems to be no 



