170 VEGETATION OF THE PEAK DISTRICT [CH. 



Tansley (1911 : 208) has recently discussed the conditions 

 of British moors and fens ; and in his Types of British Vege- 

 tation, accounts are given of the vegetation of the two plant 

 formations. The " fenland formation " of Caithness, recently 

 described by Crampton (1911 : 74), is certainly not true fen, 

 but a type of vegetation intermediate between fen and moor, 

 and termed Uebergangsmoor (transitional moor) by Weber 

 (1908: 95). 



MOORS AND FENS 



The only test of fen peat and moor peat, which is here 

 regarded as really fundamental, is that depending on the 

 amount of soluble mineral matter in the peat; and as this 

 is very low in the case of all the local peats examined, there 

 is no difficulty in referring all the plant associations developed 

 on peat in this district to the moor formation as opposed 

 to the fen formation. 



The following characteristics distinguish the two forma- 

 tions : 



1. Fen peat is rich, moor peat is poor in soluble mineral 

 matter. 



2. Fen waters are alkaline, moor waters acid in reaction. 



3. Fen peat often, moor peat rarely, contains the remains 

 of molluscan shells. 



4. The following plants are locally subdominant or very 

 abundant on the peaty fens of eastern England: 



Cladium Mariscus Calamagrostis lanceolata 



Schoenus nigricans Molinia caerulea 



Phragmites communis Juncus obtusiflorus 



Of these species, only one Molinia caerulea occurs on the 

 moors of the Peak District. 



The following species are locally dominant or very abundant 

 on British moors : 



Sphagnum spp. Vaccinium Myrtillus 



Polytrichum commune V. Vitis-idaea 



Rhacomitrium lanuginosum Scirpus caespitosus 



Empetrum nigrum Eriophorum vaginatum 



Rubus Chamaemorus E. angustifolium 



Erica cinerea Carex Goodenowii 



E. Tetralix Molinia caerulea 



Calluna vulgaris Juncus squarrosus 



