VEGETATION' OF BLAKENEY POINT. 
529 
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, effect. 
The chief of these cryptogamic pioneers are Cladonia rangi- 
ferina, Tortilla 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 Solaimni 
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 and Anagallis, 
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 Filago 
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 
