4 Dr. H. Franklin Parsons on the 
resorts are frequented by increased numbers of people; and the 
more showy plants suffer at the hands of trippers, and the rarer 
ones through the rapacity of collectors. Im dry seasons the . 
herbage is often destroyed by fires. When a common gets 
surrounded by houses, the smokiness of the air is unfavourable 
to the growth of certain plants, especially of cryptogams. From 
all these causes it happens that the original flora of our commons, 
especially near towns, tends to become impoverished by the loss 
of its most interesting members, while, on the other hand, intro- 
duced species of plants may be added. This leads me to the 
suggestion which is the main object of this paper—viz. that our 
Club should compile for future reference lists as complete as 
possible of the flora of each of our commons and wild spaces in 
the neighbourhood of Croydon. The compilation of such lists 
would afford opportunity for interesting comparisons between the 
floras of different open areas. Thus it would be seen what an 
almost complete difference there is between the plants growing 
on a gravelly heath, such as Shirley Hills or Keston Common, 
and those on a chalk down, snch as Riddlesdown and Farthing 
Downs. ‘The flora of a tract containing wet places, like Keston 
Common, would also contain many species not met with on a 
dry tract like Hayes Common. But, apart from these differences 
of soil, there is hardly one of the commons around Croydon 
which does not contain in its flora some plant which is not met 
with on the others. Thus Croham Hurst has the whortleberry 
and lily of the valley; Hayes Common the butcher’s broom ; 
Keston Common the sundew, bog asphodel, and meadow thistle 
(Carduus pratensis); and Chislehurst Common the bog St. John’s 
wort (Hypericum elodes) and pennyroyal. A catalogue of the 
insects and mollusca of each of these commons would doubtless 
show like differences. 
The commons on the pebble beds of the Oldhaven series have 
a peaty soil on which the heaths are the predominant feature in 
the vegetation. We find on Shirley Hills, for instance, three 
species of heath—viz. the ling, the cross-leaved heath, and the 
purple heath. Of these the latter is confined to dry places, and 
the cross-leaved heath to wet places, while the ling is ubiquitous 
there. The larger terrestrial mosses and lichens and fungi are 
plentiful, and in the wet hollows boggy places are formed where 
plants such as Sphagnum, sundew, and petty whin occur. Where 
the pebble gravel is less sharp and the top soil is loamy, the gorse is 
the predominant shrub, as on Hayes Common and Chislehurst 
Common, and also on the alluvial gravel of Mitcham Common. 
Where the soil is fine sand, as on parts of Shirley Hills, Hayes 
Common, and Mitcham Common, minute annual plants, such as 
species of Trifolium and Cerastium, Menchia erecta, Ornithopus 
perpusillus, and Hrodium cicutarium are found. 
