402 Flahault: Phytogeographic Nomenclature 



the environment or in the conditions determined by the presence 



of other plants. 



Among the species which go to make up the association, some 

 are dominant, either by the action they exert on the habitat in creat- 

 ing, as it were the station, or because they are characteristic of the 

 plants of the country, in the form, size, or numbers of individuals ; 

 they form then the foundation of the vegetation. Others are second- 

 ary y more or less isolated, as if they had been scattered over the 

 fundamental vegetation ; or else are they subordinated in various 

 degrees, either because they are scarce or rare, or it may be that 

 they cannot live except in the shelter of the first, in their shade, as 

 epiphytes on their aerial organs, or at their expense as parasites. 

 They can also be subordinated by the limited duration of their 

 active life (annuals, biennials, bulbous plants, etc.). The dominat- 

 ing species always characterize the association. 



Association, so understood, answers exactly to what we have 

 admitted since 1893, to that which has been described as such 



Warming 



Robert Smith, 



in Scotland ; F. Hock, in Germany ; Schroter, in Switzerland. 



The term Association [Plant association) has been applied to it 

 by English-speaking botanists. Warming called it Plantcsamfnnd 

 (in Danish) Pflanzenverein ; Kerner described it under the term of 

 Genossenschaft ; Hock also called it by the name of Bestand. 

 There are nevertheless divergences of opinion in regard to Associa- 

 tion. W. O. Schimper regards it as composed of special ecologic 

 groups : " It is the union of plants dependent on one another, some 

 of which have always a dependent character and are unable to live 

 without the help of others."* He recognizes four kinds of eco- 

 logic associations of this sort — lianas, epiphytes, saprophytes 

 and parasites ; these are groups of biologic forms, not of asso- 

 ciations as understood by A. P. de Candolle and Humboldt. 



If association is the simplest biologic unit from the geo- 

 graphic point of view, the ultimate expression of the struggle for 

 life and adaptation, biologic forms may be considered as elemen- 

 tary units from a special ecologic point of view, as species are 

 the elementary units which the botanist employs. 



Mr. Warminp" has broucrhf ini-n r r\rr&] ^ «•;/-»« uri+i. «-v.o o*-i<-» <-»f mir 



* W. O. Schimper, Pfianzengeographie, 208. 1898. 



