32 G. D. FULLER AND A. L. BAKKE 



heath upon the dry hills of the interior of northern Spain, Thymus 

 hiemalis formation. 



These four formations were examined by the 'S^alence method." 

 Results are given in tables 1, 2, 3 and 4. These tables show 

 the characteristics of the formations in question in so far as 

 nanophanerophytes and chamaephytes are concerned. For 

 the west Jutland heath and the southern France maquis there 

 are also included species representing the phanerogamous flora 

 as a whole. This is not the case with the formations from north- 

 ern Spain where the phanerophytes and chamaephytes only 

 are in evidence. There is no similarity between the small shrubs 

 and the remaining life forms. It is certain that these are es- 

 sentially shrub formations; formations in which the nano- 

 phanerophytes and chamaephytes predominate. 



In tables 1 to 4 the dominant species of the formation are 

 given in order of importance, and the other species are arranged 

 alphabetically. In the first column after the name of the species 

 the "life-form" to which the species belongs is given, in the 

 second the species' valence in terms of per cent, and finally in 

 the third column there is given the "size-class" of all the simple 

 (including lobed) leaved evergreen phanerophytes and cham- 

 aephytes. 



The tables show four formations differing in various ' ays. 

 The nanophanerophytes and chamaephytes dominate most com- 

 pletely in the Calluna vulgaris formation, the poorest in number 

 of species possessing 5 only; then follows the Thymus hiemalis 

 formation with 7 species; the Arbutus unedo and Quercus cocci- 

 fera formations with 12 species, and the Erica muUifiora for- 

 mation with 22 species. The sum of the valence numbers of 

 the nanophanerophytes and chamaephytes shows the Thymus 

 hiemalis formation standing first. Arranged according to a 

 physiological viewpoint, that is, according to the height of the 

 vegetation, the Thymus hiemali is lowest, then follows Calluna 

 vulgaris and finally the most vigorous Arhutusunedo and Quer- 

 cus coccifera. 



We shall now inquire whether a significant comparison upon 

 the basis of leaf-size can be made between evergreen phane- 



