VOLUME LXXIV NUMBER 1 
THE 
BOTANICAL GAZETTE 
September 1922 
DEVELOPMENT OF PLANT COMMUN ITIES OF A 
SAND RIDGE REGION IN MICHIGAN 
W. G. WATERMAN 
(WITH TWELVE FIGURES) 
Plant synecology is the study of the relations of plant communi- 
ties to their environment. The subject may be divided into three 
major sections. 
1. Morphological and physiological synecology.—The physiog- 
nomy, ecological structure, and floristic composition of plant com- 
munities and their relationship to the factors of the environment. 
This includes not merely an enumeration of the species and 
ecological forms present, but also the sociological value of the dif- 
ferent members of the community, as suggested in the following 
topics: abundance, dominance, affiliation, genetic _ importance, 
constancy, etc. 
2. Geographic synecology.—The distribution of plant communi- 
ties, with special reference to the influence of the factors of environ- 
ment. 
3. Genetic or dynamic synecology.—The study of the develop- 
ment of plant communities on unit areas as the result of the action 
of biotic factors, modified by physiographic influences and by 
changes of climate. 
In the early days of ecology, the distributional phase of synecol- 
ogy was more evident and was followed with almost no suggestion 
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