190 



PLANT SOCIOLOGY 



"red soils" of southern Europe, southern United States, and 

 cUmatieally similar regions. The deep-red bauxite concretions embed- 

 ded in the upper layers of limestone are especially rich in iron 

 (bauxite is considered to be chiefly amorphous A1(0H)3 - gel). 

 In the large deposits of southern Europe bauxite appears to be in no 

 wise detrimental to plant growth. Upon exposure of these deposits the 

 species of the immediate environment soon establish themselves, lime 



Polytrichetum 

 sexangularis 



71 Salicetuni 

 J herbaceae 



Elyuetiim 



ocj Curviiletum 



Fig. 102. — Acidophilous associations upon the Ochsenkopf. Central Alps, 2,400 m., 

 upon serpentine. {After Braun-Blanquet and Jenny.) 



plants as well as indifferent species. Among the abundant species are 

 Spartium junceum, Dorycnium suffruticosum, Euphorbia nicaeensis, 

 Helichrysum stoechas, and Inula viscosa. The vegetation of the 

 immediate environment of the Jurassic iron pits is composed solely of 

 indifferent and Hme-favoring species (Gontejean, 1881). The vegeta- 

 tion is quite different near the deposits of iron blende and pyrites of 

 upper Italy. Large areas are entirely barren. The first pioneers of 

 this soil, heavy with oxides of iron, are calciphobous plants, such as 

 Calluna, Agrostis canina, Silene rupestris, and the indifferent Molinia 

 coerulea (Gola, 1910), all somewhat dwarfed and chlorotic. 



Iron species are unknown, ^ with the exception of a peculiar iron- 

 favoring community of microorganisms (Molisch, 1910). In moor 



1 According to Vicillaid, the red soils of New Caledonia, rich in iron, are said to 

 exhibit an entirely characteristic flora, which includes Dammara ovata, Eulassa 

 intermedia, and Dacrydium caledonica. 



