42 VEGETATION OF BLAKENEY POINT. 



reflected in the abundance of ephemeral plants on the older 

 phases in the early part of the year, which pass through their 

 life history in those few months in which the rainfall is greatest. 

 In the late autumn and spring these plants form an almost 

 continuous carpet, but by July they have nearly all shed their 

 seeds and become so dried up as to leave little evidence of 

 their former dominance. Chief amongst the ephemerals are 

 Cerastium tetrandrum, Erophila vulgaris, Cerastium setni- 

 decandrum, and Stellaria Borceana ; whilst scarcely less 

 abundant are Phleum arenarium and Myosotis collina, all of 

 which probably play an important part in surface protection 

 during a critical period of the year. Where there are depressions, 

 such as local subsidences due to rabbit holes, in which the soil 

 remains damp even in summer, ephemerals may still be found 

 in the later months, particularly Stellaria Borceana, but such 

 exceptions merely emphasise the dependence of these shallow- 

 rooted plants on surface moisture. 



The Sand-Binders. 



The sand-binder par excellence is of course the Marram 

 grass, which furnishes the skeletal structure of the system but 

 does little to fix the actual surface itself. The latter function 

 is to a large extent performed by Festuca arenaria, which 

 comes in at an early stage, and locally we also find the sand 

 sedge (Carex arenaria), but always in situations of comparative 

 shelter, as though climatic conditions were an important factor 

 in its distribution. 



The sea convolvulus, which elsewhere plays a conspicuous 

 part in the fixation of sand, is on our area confined to a single 

 flat-topped dune on the lee side of the main ridge. In this one 

 spot it is the most abundant plant, and associated with it are 

 Senecio Jacobcea (c), Anagallis arvensis (c), Cerastium semi- 

 decandrum (c), Erodium cicutarium (f.c.), Psamma arenaria 

 (f.c.), and Silene maritima (r.r.) 



The following list is compiled from the dunes of the Head- 

 land, and fairly represents the flora in this phase. The only 

 species which calls for special remark is Elymus, represented 



