VII] MOORLAND ASSOCIATIONS 167 



10. Cotton-grass moor. Association of Eriophorum 

 angustifolium (Eriophoretum angustifolii). 



11. Scirpus moor. Association of Scirpus caespitosus 

 (= Trichophorum caespitosum) (Scirpetum caespitosi). 



These two associations are described by Pethybridge and 

 Praeger (1905 : 166 7), and occur on the Wicklow mountains 

 south of Dublin. In certain Scottish localities also, namely, 

 in the north-western Highlands, in the Hebrides, and in the 

 Shetlands, " Scirpus caespitosus dominates the most character- 

 istic associations. In N t W. Sutherland, the flat, basaltic plateau 

 of northern Skye, and the valley floors and gently sloping hillsides 

 of Shetland, this type remains dominant over many hundred 



square miles In the western portion of N. Uist, the Scirpus 



caespitosus association extends over hills of low elevation and 

 broad shallow valleys " ([F. J. Lewis, in] The New Phytologist, 

 1908 : 257). Scirpus moors resemble the cotton-grass moors and 

 heather moors of the Pennines in the comparative scarcity of 

 bog-mosses (Sphagnum spp.). 



12. Rhacomitrium moor. Association of Rhacomitrium 

 lanuginosum (Rhacomitrietum lanuginosi). Pethybridge and 

 Praeger (1905 : 167) describe a modification of the heather moor 

 and the Scirpus moor brought about by the local dominance 

 of a species of woolly moss (Racomitrium lanuginosum). The 

 association of Rhacomitrium lanuginosum would appear to be 

 fairly widespread in western Scotland ; and " Rhacomitrium 

 bogs" in Caithness are described by Crampton (1911: 55). 



All the above associations and societies occur on peat which 

 is marked by acidic waters, and by a low soluble mineral- 

 content, especially by a low lime-content. The plant formation 

 of such a habitat has been termed an Oxodion (Moss, 1910 b : 

 43) ; and its described chief associations in the British Isles may 

 be designated as follows (cf. Moss, loc. cit.} : 



Oxodion Calluneti-vulgaris 

 Oxodion Eriophoreti-vaginati 

 Oxodion Vaccinieti-myrtilli 

 Oxodion Sphagneti-recurvi 

 Oxodion Eriophoreti-angustifolii 

 Oxodion Scirpeti- caespitosi 

 Oxodion Rhacomitrieti-lanuginosi 



