East Anglian Heaths 97 



The East Anglian "heaths," particularly those in the neighbourhood 

 of Mildenhall, Brandon and Thetford, include considerable stretches of 

 dry grassland which are not however quite typical grass heaths, such 

 plants as Agrostis canina and Deschampsia flexuosa and several other 

 typical grass heath species being absent. The soil often contains 

 appreciable quantities of lime. These areas of grassland alternate with 

 true (Calluiia) heath. The region has a low rainfall (less than 25 inches 

 per annum) and exhibits the nearest approach to steppe-conditions to be 

 found within the British Isles. The vegetation tends to be sparse and 

 the tufts of ling or grass are often wide apart, the intervening spaces 

 bearing a scattered vegetation of ephemerals. It is doubtful if this area 

 ever bore natural woodland. 



The existence of widespread steppe conditions, subsequently to the 

 glacial period, is now generally recognised. Between the glacial period 

 and this steppe period, a fairly warm epoch intervened, with the coast- 

 line not far from its present position. In the steppe period a considerable 

 elevation occurred, and much of the North Sea was land. Such a period 

 was favourable to the accumulation of loose sands, like those of the 

 Mildenhall district, and there is evidence that the formation of these 

 sands has been going on for some time. A steppe flora must have been 

 widely distributed during the steppe period, and as we find fossil steppe 

 mammalia in England, we should expect that steppe plants also occurred 

 here. If we have survivors of the glacial flora under suitable conditions, 

 we should expect survivors of the more recently arrived steppe flora also. 

 The Mildenhall sandy tract has several plants not found elsewhere in 

 Britain and these may well be the survivors of that flora i. 



The following plants are confined, or nearly confined, within the 

 British Isles, to this region : — 



SUene Otites Veronica verna 



S. oonica V. triphyllos 



Holosteum umbellatum Muscari racemosum 



Medieago Falcata Ornithogalum umbellatum 



M. sylvestris Carex ericetorum 

 Artemisia campestris 



1 The editor is indebted for this paragraph to Dr J. E. Marr. 



