1911— 1J.] BOTANICAL SOCIETY OF EDINBURGH 85 



The variety glandidosum, Bosch., of Erodium cicutariu m 

 has been recorded from this district. Anaphalis mar- 

 ga/ritaeea is well established on the dunes, and apparently 

 succeeds best where competition is reduced to a minimum. 

 Cnicus arvensis colonises the sandy hollows towards the 

 inner limit of the mobile dunes. It is also abundant on 

 the fixed dunes, as in Norfolk. Euphorbia, portlandica is 

 absent from the Somerset sand hills. 



Salix repens Association. 



As already mentioned, this association includes within 

 its limits plants of the mobile dunes, as well as those of the 

 fixed dunes. The following species occur : — 



DOMINANT SPECIES. 



Salix ," /" ns, Linn. 



SUBDOMINANT SPECIES. 



Rubus ccesius, Linn. Arn/mophUa arenaria, Linn. 



FREQUENT SPECIES. 



Viola ericetorum, Schrad. Leontodon (nudicaule), B. 



Viola Curtisii, Forster. & S. 



Erodium cicutariiim, Euphorbia Paralias, Linn. 



L'Herit. Iris fcetidissvma, Linn. 



Rosa spinosissima, Linn. Carrex arenaria, Linn. 



Erigeron acre, Linn. PMev/m arenarium, Linn. 

 Cnicus arvensis, Hoffm. 



Viola Cv/rtisii was recorded from the sand dunes near 

 Aberavon, over sixty years ago. It is not found in 

 Somerset. The damp sand} T hollows which occur within 

 the limits of the Salix association possess a characteristic 

 vegetation. These depressions lie at a low level, and during 

 the winter months are frequently submerged. A laj'er of 

 humus is formed in places, and in conjunction with an 

 increased water content produce a plant society of a definite 

 type. The Salix forms a fringe round the margin of these 

 hollows, which are colonised by the following species : — 



