
74 BOTANICAL GAZETTE [FEBRUARY 
be called organographic ecology or even organography, while 
the latter may be called ecological anatomy. 
It may be well to speak more in detail concerning the dis- 
tributional phase of ecology. There are two distinct aspects 
here also, the one local, the other regional. Climatic factors, 
particularly temperature and atmospheric moisture, permit the 
subdivision of the earth into great zones or regions with charac- 
teristic plant formations which extend over wide areas. Exam- 
ples of this type are tropical evergreen forests, deserts in 
continental interiors, prairies, deciduous forests, arctic tundras. 
These formations are widespread because the factors that pro- 
duce them are widespread. We might call these formations cli- 
matic formations (following Schimper’) and the subject that 
deals with them geographic ecology or ecological plant geogra- 
phy. In contrast with the above there are the local or edaphic 
factors, such as soil (including its moisture, air, and temperature 
relations), slope, light; in other words, factors that are largely 
due to the physiographic nature of the district. Where the cli- 
mate is the same these factors produce marked changes locally, 
and there results a variety of plant societies, such as swamp, 
dune, bottom forest, river bluff, etc. These correspond to 
Schimper’s' edaphic formations or Warming’s plant societies, and 
the subject that deals with them may be called physiographic 
ecology. 
In order to justify the terminology here given it will be 
desirable to trace briefly the history of the study of plant socie- 
ties and then to depict the intimate relations which exist between 
the physiography of a region and its flora.’ Before the appear- 
ance of Warming’s ecological plant geography” there had been 
no attempt to classify the plant formations of the globe in a sys- 
tematic manner. Warming introduced the term plant society in 
place of plant formation, because of the varied use of the latter, 
*SCHIMPER, A. F. W.: Pflanzengeographie auf physiologischer Grundlage 
173-176. Jena, 1898. 
* WARMING, E.: Plantesamfund. Copenhagen, 1895. German edition, trans- 
lated by Knoblauch. Berlin, 1896. 

