120 VEGETATION OF THE PEAK DISTRICT [CH. 



grassland and calcareous grassland, should not be placed in the 

 same plant formation ; and the same conclusion is indicated by 

 a study of their floristic composition and the related plant 

 associations. 



Gradmann (1909: 94) has maintained that a plant forma- 

 tion can be defined floristically; and if this conclusion be 

 accepted, it would seem to be indicated that the siliceous 

 grassland and the calcareous pasture, although often possessing 

 the same physiognomy and the same plant form, must be 

 assigned to different plant formations. 



On bushy banks, where there is some shelter from the wind 

 and where the soil is comparatively damp, many shrubs of the 

 ash woods and of calcareous scrub occur; and these shrubs, in 

 their turn, shelter several herbaceous species of the ash woods 

 and scrub. Many of such communities, in fact, appear to be 

 progressive associations which will finally become ash woods; 

 and it is impossible to draw any hard-and-fast boundary line 

 between woods, scrub, and grassland either of the siliceous or 

 the calcareous soils of this district. The transitional associa- 

 tions of these hill-slopes are strictly analogous with the tran- 

 sitional associations occurring on the wet, acidic, peaty soils of 

 the " Hochmoors so abundantly scattered in the foothills on the 

 Jura ridges, the Black Forest, and the Vosges. In contrast to 

 the Hochmoors of the north German plain, there occurs here, 

 as is well known, Pinus montana in great communities, but by 

 no means everywhere: even on the moors where it flourishes, 

 wide stretches are often quite free from it. If one now starts 

 with the ordinary physiognomical division [of forests, scrub, 

 grassland, etc.], it becomes necessary to split the natural and 

 sharply defined plant community of the Hochmoor into at least 

 three if not into four or five formations ; and these must further 

 be assigned to the most varied positions in the system. 

 According as Pinus montana forms well-developed trees, or 

 is the dwarfed form, or is absent altogether, the bit of the 

 Hochmoor in question belongs to the forest formations, or to 

 the scrub formations, or to the moss formation : where Ericaceae 

 occur socially the same Hochmoor becomes a dwarf-shrub 

 formation : where a turf of Carices, Eriophorum, or Scheuch- 

 zeria predominate, we have a ' meadow.' And yet the floristic 

 composition is almost exactly the same : the local conditions, 



