The Brecklaiid 225 



Festuca ovina and Agrostis spp. ; but an effective, and sometimes colourful, 

 contribution is made by Asperula cymttchica. Astragalus danicus, Campanula 

 rotundifolia, Carex praecox, C. ericetorum, Galium verum, Koeleria gracilis, 

 Linum cathartiaim, Lotus corniculaUis, and Thymus serpy Hum. There are many 

 species of bryophytes but both they and the lichens play a subsidiary part. 

 Cladonia silvatica is frequent as "individuals", but never forms pure 

 patches. 



Grassland C. This type, briefly, is Grassland B w^ithout its large calci- 

 colous element; but many exacting species remain. The surface soil is novi^ 

 acid, and Galium saxatile, Rumex acetosella, Teesdalia nudicaulis and Hypnum 

 schreberi appear in considerable numbers. The turf is more grassy and 

 coarser than in B : Festuca ovina and Agrostis spp. make up its bidk, but 

 Campanula rotundifolia, Carex praecox, and Galium verum, are frequent to 

 abundant. There are many species of bryophytes including the character- 

 istic Bryum roseum. The most abundant lichen is Cladonia silvatica, and it 

 occasionally forms small pure patches under which are found the dead 

 remains of higher plants. 



Grassland D. A further drop in soil fertility is reflected in the absence 

 of many exacting species, leaving only thirty-seven higher plants. More- 

 over, the grassy turf is not continuous, and die vegetational cover consists 

 essentially of patches of higher plants and patches of Hchen with Cladonia 

 silvatica dominant. Again, Festuca ovina and Agrostis spp. are the chief 

 plants : the relatively exacting Campanula rotundifolia and Galium verum are 

 less frequent than in C, while the calcifuges Galium saxatile, Rumex aceto- 

 sella and Teesdalia nudicaulis are more frequent than in C. There are many 

 fewer species of bryophytes. 



Grasslands E, F and G. These tliree types are essentially the same. Eight 

 tolerant significant species of higher plants grow in patches, or scattered in 

 a carpet of lichen composed almost entirely of Cladonia silvatica. These 

 species are Agrostis spp., Aira praecox, Festuca ovina, Galium saxatile, Luzula 

 campestris, Rumex acetosella and Teesdalia nudicaulis. The greater number of 

 species (higher plants and bryophytes) which differentiate E and F from G 

 are found largely on soil thrown up by rabbits, thus expressing die fmer 

 chemical differences in the three stages of podsolisation represented. 



Everywhere, underneath the hchen carpet, occur the remains of grasses, 

 Rumex, Luzula, and occasionally Calluna vulgaris. 



A study of the full lists of species and their distribution among the types 

 of grassland brings out very clearly that from B to G the flora is an attenu- 

 ating one: there is a fractional elimination of species rather than a radical 

 change. First the calcicoles go; then the more exacting, followed by the 

 less exacting, until finally in G only the tolerants survive. Only a small part 



