VEGETATION OF BLAKENEY POINT. 45 



and mosses are a pronounced feature of the vegetation, and 

 with the additional phanerogams, bind and protect the surface, 

 which the Psamma, knitting together the sand below, cannot, 

 from its diffuse habit, eftect. 



The chief of these cryptogamic pioneers are Cladonia rangi- 

 ferina, Tortula ruraliformis, Dicranum scoparium, and species 

 of Hypnum. 



Although far more stable than the main system, the position 

 of the Long Hills is such that their seaward end and southern 

 face are subject to considerable erosion, and furnish support 

 for Salsola Kali, with which is occasionally associated Solatium 

 nigrum ; also on the less mobile parts of the edge Stellaria 

 Borceana occurs in quantity, as elsewhere on the barer sand 

 when relatively stable. 



Environed as the Long Hills are by the laterals which form 

 their base, the periphery is often half pebble, half sand, and 

 supports a corresponding flora ; also in the middle of these 

 dunes there is a depression which in the centre lays bare the 

 shingle, but, unlike the shallow sand of the outer edge, which 

 is bare and mobile, that which surrounds this central region is 

 sheltered and clothed. 



On the outer margin are several species which are infrequent 

 or absent from the central parts, and of these, some, like 

 Armeria, Arenaria, Atriplex, Rumex trigranulatus, and Silene, 

 may be regarded as due either to their relict character or to the 

 mingling of sand and shingle; others, like Senecio andAnagallis, 

 serve to indicate that here the conditions of the shifting dune 

 are longest retained. 



Several species are characteristic of the shallow fixed sand, 

 around the central depression and elsewhere. These are Ftlago 

 minima, Plantago Coronopus f. pygmcea, and Agrostis mari- 

 tima, and their occurrence here is doubtless associated with the 

 close proximity of the shingle below, since the first is a typical 

 gravel heath plant and the remaining two are both frequent 

 upon the older lateral banks. 



A very pronounced feature of these dunes is the presence of 

 several hummocks in the central region colonised by Polypodium 



