230 M. C. Rayner, W. N. Jones and J. W. Tayleur. 
clay-with-flints, but “ loam ” is marked at intervals, and the flora 
suggests that a cap of this nature extends to the edge of the 
escarpment, as Ulex europczus, Cratcegus monogyna, and Rubus Idceus 
occur, growing with which the following herbaceous species have 
been noted— Epilobiuinangustifolium,Epilobiummontanum, Geranium 
Robertianum, Holcus lanatus, and Veronica Cliamcedrys. A few 
sporadic plants of Calluna were recorded growing within twelve 
inches of such a typical chalk plant as Helianthemum vulgare. 
Further west, on Botley Down, Calluna becomes abundant with 
the distribution described. 
Calluna has been established here for at least twenty years, 
and in spite of attempts to remove it, has shewn and still shews 
an inclination to spread. It is doubtful whether the land bearing it 
has ever been under plough, but there is arable land in the 
immediate neighbourhood. 
.Superficial examination suggests that in this neighbourhood 
the heather has picked out the more fertile soils, on which it has 
become established to the exclusion of the plants of the surrounding 
vegetation. 
How the plants gain a foothold in the first instance, and how 
the spread is effected, constitute a distinct problem. Seed is 
freely produced and germinates readily, although rather slowly and 
irregularly. The seeds, however, are small, and the resulting 
seedlings extremely slow-growing. In pot cultures the development 
of the root system is slow and the seedlings are easily injured in 
the young stages. Ant heaps and mole hills are common on the 
surrounding Downs and often carry a rather distinct flora owing no 
doubt in part to the baring of the soil. These may afford the 
Calluna seedlings a starting point, although the surface is usually 
very dry during the spring and summer. Up to the present, 
seedling stages have not been observed either in such situations 
or on the downland in the neighbourhood of the mapped area. 
Before recording the results of observations on the soil conditions 
with which Calluna is associated on the small area investigated, 
a summary of previous literature on the subject may be of interest. 
Schimper (3) mentions Calluna as a typical heath plant, the 
only member of the family Ericaceae which forms independent 
heath formations. It may form the chief constituent over large 
tracts of country if the soil is very poor in lime, on both sandy and 
moory stations, the former being physically, the latter physiologically 
dry. Schimper further notes that both sand and peat are very 
