26 
C. E. Moss. 
into associations ; but his use of the terms appears to me to be rather 
inconsistent. With regard to woodland communities, his “forma¬ 
tions ” are rather narrow and circumscribed, like those of Hult. For 
example, Brockmann-Jerosch speaks of “ formations” of Castauea 
vesca [C. saliva] , of Pinus sylvestris, and so on. These units are, 
in my judgment, associations ; and they were so treated by Flahault 
{op. cit.). It is significant that Brockmann-Jerosch does not 
subdivide these narrow woodland “ formations ” into associations ; 
but that wider formations, such as “ Sumpfwiese,” he is able to 
analyse into associations, such, for example, as associations of 
Phragmites communis and of Molinia coendea. 
Moss (1907) was the first among British ecologists to speak 
both of formations and associations. Thus, the sand dune formation 
of Somerset may be subdivided into progressive associations of 
strand plants ( Atriplex spp., etc.), of sea-couch grass {Agropyrum 
junceum), of marram grass (Ammophila arenaria), of dune sward¬ 
forming plants, of dune pasture plants, and of dune marsh plants. 
Similarly, in the acidic peaty moorland formation of the Pennines, 
stable associations of Calluna vulgaris and of Eriophorum vaginatum 
may be distinguished, and also retrogressive associations of such 
species as Vaccinium Myrtillus, Empetrum nigrum, and Rubus 
Chamaemorus in varying proportions. 
Warming (1909: 139, et seq.) followed what has become the 
general practice of subdividing the formation into associations. 
The latter he defined (p. 145) as follows:—“An association is a 
community of definite floristic composition within a formation.” 
This point of view may now be regarded as having become all but 
universal ; but it would be better to refer to the minor differences 
of habitat as well as to the differences of floristic composition in all 
definitions of the association. By so doing, the main object of the 
study of vegetation would be emphasized ; and a tendency—by no 
means an imaginary one—to regard plant geography as a branch of 
floristic botany would be checked. It is perhaps overbold for a 
science that is still only in its infancy to state that it depends upon 
“ mere accident ” whether one or other of these associations prevails 
at a given spot (Warming 1909: 140), especially as, in many instances, 
these minor differences in habitat may be actually demonstrated. 
It will be seen that the concept of the plant association, and 
also the term, have been long established, and that they have come 
to be very widely accepted among ecologists and plant geographers 
of several nations. Although for a time the term was threatened 
