E. V. Wulff — 210 — Historical Plant Geography 



Mention should here be made of the so-called " pseudo- Atlantic " 

 species (Braun-Blanqtjet, 1923), characterized by the fact that, al- 

 though they are ecologically close to the Atlantic species and are 

 chiefly restricted in their habitats to the sandy strips along the shore 

 and to humid climatic conditions, they have a very extensive range and 

 are, in reahty, wides (polychores) . This group, therefore, does not 

 constitute a floral element in a geographical sense. 



There has been no lack of different interpretations of the Atlantic 

 element. The chief confusion lies in the fact that this term is fre- 

 quently used as a synonym for "oceanic element" (ozeanischer Ele- 

 ment), as comprising species adapted to humid habitat conditions. 

 The oceanic element is a type of ecological element; hence, to confuse 

 it with the Atlantic element (a geographical type) or to make these two 

 terms synonymous, as some investigators do, is entirely incorrect. 



The geographical types of elements in Russian phytogeographical 

 literature have ordinarily been designated not by special terms, such as 

 those we have just enumerated, but simply by indicating the geograph- 

 ical regions that served as the centers of origin of these species, e.g., 

 the Altai, Mediterranean, etc. elements. In this way the confusion 

 found in west-European literature was to a considerable extent avoided. 

 Of the few terms applied with respect to the flora of the U.S.S.R. we 

 may mention the following: — 



Hirkanic element — species distributed chiefly in the forest and humid regions of north- 

 ern Iran. 



Colchic element — species similar to the foregoing but having their chief center in 

 western Transcaucasia. 



Turank element — species of the Aral-Caspian region, of a desert, xerophytic type. 



To devise more special terms is, in our opinion, not of particular 

 service, since such terms are not an aid in understanding the species 

 composition of floras and merely create confusion due to their being 

 variously used and interpreted. 



Ecological Elements: — Of the ecological elements those of most 

 vital significance are: the oceanic element, embracing groups of species 

 adapted to conditions of a humid, maritime climate; and the conti- 

 nental element, embracing groups of species adapted to an arid, conti- 

 nental climate. Of these two chief ecological elements only the first 

 has been well investigated, so that we shall discuss it in greater detail. 



Oceanic Element.— In conformity with the very definition of this 

 element as embracing species of a humid climate, it is to be expected 

 that such oceanic species will form part of different geographical ele- 

 ments. All species belonging to the Atlantic element will, at the same 

 time, in an ecological sense, be oceanic elements. It would be entirely 

 incorrect, however, to identify completely the Atlantic and oceanic 

 elements and to use the term Atlantic element in an ecological sense, 

 understanding by it floral elements adapted to a humid climate regard- 

 less of their geographical location. Likewise, only confusion is intro- 

 duced by designating such hydrophytic elements as Iberian, Lusitanian, 

 Macaronesian, insular, etc., when one has in mind not the geographical 

 but the ecological character of these elements. Hydrophytic elements 

 of floras, regardless of their geographical distribution, should be desig- 



