201 



the base of tlie hills, ou the tension line adjoining the swamp, is the 

 black huolileberry, Gaylnssacia resinosa. (See liaclvgronnd of Fig. 3.) 

 The oalv stage has reqnired i-o long a time to develop and has been in 

 existence so long that we liave only the resnlt and little evidence of what 

 preceded this type. In tlie noi-Tli tlie coniferous forest comes first. Clear- 

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

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

 another much more rapidly than they would in a virgin soil in which 



Fifr. 5. View uf the channel and abutments of the ujiper or lesser dam. From the con- 

 dition of the vegetation in the foreground, it is evident that the stream's gradient is small. 

 Ujion 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. ^Yhere the soil has 

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

 sides of the lake, are Xerophytic annuals and perennials, such as poke 

 weed (Phytolacca decandai, mullein (Verbascum thapsus), Canada thistle 

 tCnicus arvensisi, hounds-tongue (Cynoglossum otfieinale). Leonurus Car- 

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

 lowed l)y elm and hickory. The beech-maple forest is working its way 

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



