Chapter XI — 209 — Concept of Floral Elements 



northern Africa and on the Madeira and Canary Islands. These are 

 floral elements that cannot yet be divided into pure Mediterranean and 

 pontic elements. Out of these elements there arose the pontic elements 

 only after the territory of the pontic floral region was uplifted above 

 the level of the sea and became inhabited by plants, which could have 

 occurred not earlier than the PHocene (Ludwig, 1923). Hence, we 

 have here precisely that type of plant links that Eig had in view. 



4. Atlantic element. By "Atlantic element" in the geographical 

 sense one understands that group of species whose distribution is, as a 

 whole, restricted to the Atlantic coast region of Europe. Islands lying 

 in the Atlantic Ocean west of Europe and northern Africa are not in- 

 cluded in the range of this element. Hence, the main area of distri- 

 bution of this element is the Atlantic coast of Europe — northern 

 Portugal and Spain, western and northern France, the British Isles, 

 and as far north as the Faroe Islands, western Jutland, and the south- 

 ern coast of Norway. The humid, maritime climate, with its uniform 

 distribution of precipitation throughout the year and its warm winters, 

 has contributed to the homogeneity of the flora of this part of western 

 Europe. 



The Atlantic element may be much more precisely determined than 

 the pontic element, since its area of distribution is not transitional be- 

 tween two other elements. It comprises only a few plant links having 

 connection with neighboring regions. Moreover, the distribution of 

 species of the Atlantic element are, in general, much restricted, due to 

 the predominance at the present time throughout the most of Europe 

 of continental conditions not suitable for these species. 



The Atlantic element has been subdivided in various ways by 

 different investigators. Steffen (1935, pp. 373-4) has summarized 

 these in the following tabular form : — 



I. Atlantic floral dement (in sensti strictu). The species belonging to this element are 

 either restricted in their distribution to the region of the Atlantic coast of Europe 

 or, if they have spread beyond this region, then only in projecting spurs. 



A. Eu-Atlantic Group: Compact distribution in the given region; spurs into 



neighboring floras very few or none at all. 



(Here belongs Troll's (1925) hyperoceanic subgroup, embracing species 



growing in the most humid places of the region of the Atlantic flora). 



B. Sub-Atlantic Group: Similar to A, but with considerably more extensive spurs 



into neighboring floras. 



1. Atlantic-Submediterranean Subgroup, with spurs extending, for the most 



part, into the region of the Mediterranean flora. 



2. Atlantic-Subarctic Subgroup, distributed chiefly or exclusively in the north- 



ern part of the Atlantic coast region of Europe, with spurs extending 

 into the subarctic. 



3. Submaritime Subgroup, with spurs in several directions, including regions 



with a more or less continental climate. 



II. Atlantic-Mediterranean Group, a group intermediate between the Atlantic and Medi- 

 terranean groups, requiring not only maritime climatic conditions but also high 

 temperature. 



III. Atlantic-American Group, embracing those species of the European Atlantic seaboard 

 found also along the Atlantic coast of North America (identical or vicarious species). 

 These species are, undoubtedly, remnants of a once-united flora, now separated by 

 the Atlantic Ocean, and constitute perhaps the most ancient representatives of the 

 Atlantic element. 



