436 Wisconsin Academy of Sciences, Arts, and Letters. 
The NEW element lias seven members in this list aggre¬ 
gating about forty per cent of all the vegetation. It also leads 
in number of species in every association except the mixed as¬ 
sociation. The high precentage of northern, eastern, and west¬ 
ern elements in such a marsh meadow is clearly evident. 
It is to be noted that the western element present here is 
also a northern element and that there is an absence of any ele¬ 
ment that is S W or even N S W. These facts apply to the 
vegetation as a whole according to MacMillan’s analysis of the 
Minn. River Valley, the cause of which is to be found in the 
“southeasternness” of the area as a whole. 
While the vegetation of this marsh meadow shows this in¬ 
fluence in the presence of a strong eastern element there is in 
the important northern element an evidence of other influence. 
The abundance of species of northern as well as eastern range, 
especially in the wetter portions of the marsh emphasizes the 
influence of the glacial period. Five of the six principal spo- 
cies found in the marsh meadow and which comprise 72.5% 
of the total vegetation are of extra continental range, a fact 
that points to a common northern center of development. 
It should be stated in this connection that in regard to the 
species here under discussion exact data are lacking concerning 
the geographical range with the varying habitats and the cor¬ 
responding fluctuations in the vegetative and the reproductive 
vigor of the species. These facts must be determined as a 
basis for the satisfactory understanding of the abundance of a 
plant in any given locality. Plants that are no more highly 
specialized than are those here under consideration are capable 
of developing under a variety of conditions climatic as well as 
edaphic. In a general way the distribution of the species is 
known but statistics as to the relative abundance and centers 
of greatest development are lacking and the data at hand can 
not hence be shown to be definitely related to known climatic or 
edaphic conditions. 
