Flahault : Phytogeographic Nomenclature 405 



mation as a group of species which have entered a country at the 

 same time. 



It is not to be marveled at that several botanists, who had 

 doubtless lost their way in this confusion, acknowledge having 

 employed the word without thinking of its definition, because 

 others had previously made use of it 



It has not been possible to enumerate all the opinions as to 

 the meaning of the word formation. Between the two extremes, 

 the first interpretation by Grisebach and that of R. Hult there is 

 a scale of infinite shades of meaning. The confusion is like that of 

 a labyrinth. 



Kerner, however, accepted the word as a necessity u because 

 it had been introduced into science, " notwithstanding the fact that 

 he considered it badly chosen. Warming refrained from using 

 it and Robert Smith has followed his example ; his works have 

 gained thereby a decided clearness.* We ask that phytogeog- 

 raphers make a decision, but in the meantime when they speak of 

 formation we also ask that they say exactly what they mean by it. 



Meanwhile, we readily describe the word Vegetation as an in- 

 determinate grouping, as proposed by Warming. 



With Warming, the designation of Group of associations ( Ver- 

 cinsklasse) will be reserved for the designation of several associa- 

 tions subjected as a whole to the same general conditions of 

 environment. The association of beech, of peduncled oak, and 

 of the intermingled forests of our plains, etc., form a Group of asso- 

 ciations of tropophilous trees. The association of Pinus sylvcstris, 

 of P. maritima and P. Cembra, of spruces, etc., form a Group of 

 associations of resinous trees with persistent foliage. 



The following groups of associations are distinguished in France : 



Non-resinous trees with persistent leaves (cork and evergreen 

 oaks). 



Coniferous trees with deciduous leaves (larch). 



Resinous trees intermingled with other foliage (beech and 

 spruce, beech and Norway spruce, Norway spruce and birch). 



. Resinous trees and non-resinous trees with persistent leaves 

 (evergreen oaks and Aleppo-pine, cork oak and Pinus maritima). 



Rob. Smith, Plant Association of the Tay Bassin, 1898. On the study of Plant 

 Association, 1899. Botanical Survey of Scotland, 1900. 



