1000 MINNESOTA BOTANICAL STUDIES. 



floating habit has extended over several seasons, conform 

 either in kinds of plants or in grouping altogether to the at- 

 tached types. 



Anchored bog. It often happens that after floating for a 

 season or two or even for a number of years, a bog is finally 

 carried into some angle or cove from which it does not readily 

 escape and after a time, if the bottom and shore are favorable, 

 it may become anchored. This anchoring arises from the 

 growth into the bottom soil, or into the shore, of roots and 

 rhizomes from the bog group or by the growth into the bog 

 of organs from the shore group or, more commonly, by both 

 processes going on together. When thus anchored, the bog is 

 now subjected to the influences of the new environment and 

 its population becomes modified in consequence. The influ- 

 ences which affect it are both physical and biological. If 

 anchored in some area of strong illumination it develops dif- 

 ferently from what it might if the resting place had been one 

 of deep shadow. If anchored off a shore populated with 

 Coniferae the bog population will change along different lines 

 from those that might have been established had the shore 

 vegetation been of deciduous trees or of herbs. If the shore 

 upon which it has been carried is similar to that upon which 

 the anchored bog originally developed, the line of changes 

 will not be similar to those which would have taken place if 

 the landing had been made upon a totally different type of 

 shore. 



The combination and redistribution of plants which arises in 

 an anchored bog may tend either to accentuate a zonal distribu- 

 tion already established in the bog or to obliterate it. More 

 commonly the latter happens and the floating bog, unless it 

 has come to anchor in its original position upon a shore similar 

 to its shore of origin, will very soon lose all traces of its old 

 zonal aspect. It may happen that the shore is similar, but the 

 lakeward side of the bog is now turned landward, while the 

 originally landward side is turned lakeward. In such a case 

 the original zonal distribution is rapidly converted into azonal 

 and only much later will a new zonal distribution arise. 



Again, if the bog comes to rest in a state that can be de- 

 scribed only as azonal the influence of the anchorage may be 

 favorable to the continuance of this azonal condition — and this 

 is usually the case — or it may tend to convert it into zonal. 

 Even here, however, the question whether the new position of 

 the bog restores or reverses its original position must come 



