Stapledon. — On the Plant Communities of Farm Land . 167 
II. Comparison of Results obtained on the Cotswolds and in Mid- Wales 
with those recorded elsewhere. 
The weeds of arable land have in the past been studied chiefly as 
individuals and not as communities; as long ago as 1845 Bravender (2) 
published an interesting paper on these lines, and this was followed in 18 55 
by a more exhaustive article by Buckman ( 4 ). Recently, however, 
Brenchley has investigated the weed communities of arable land on the 
following chief geological formations, Greensand, Chalk, Gault, and Boulder 
Clay, and has tabulated the results obtained in three important papers. 1 
It will be of interest here to contrast the behaviour of some of the chief 
species found in the two districts under consideration with the relationships 
observed for the same species elsewhere, both by Brenchley and the present 
writer. 
A. Cotswolds. It might be expected that the highly calcareous loams 
over Oolite on the Cotswolds would carry a very similar weed flora to the 
soils over Chalk ; that the flora differs in many essentials will, however, be 
seen from the following comparison. 
The following species are all common on the Cotswolds ; but concerning 
each Brenchley in her most recent paper (Norfolk, 3 c) remarks as follows : 
Ranunculus repens .* ‘ Distributed on all soils, but seldom seen on chalk.’ 
Er odium cicutarium. ‘ Distributed on sand and very light soils.’ 
Alchemilla arvensis. ‘ Characteristic of light and sandy soils, very rare on 
chalk.’ 
Scandix Pecten- Veneris* ‘ Found on all soils, except chalk, though seen 
occasionally on chalky loam.’ 
Myosotis arvensis .* ‘ Chiefly on sand and loam, rare on chalk.’ 
Bartsia OdontitesP ‘ Chiefly associated with loam, never seen on chalk.’ 
Veronica hederaefolia. ‘Associated with sand and light sandy loams, absent 
from clay and chalk. Once dominant on loam.’ 
Polygonum Convolvulus. 1 Seen on chalky loam, but never on chalk.’ 
* These four species Brenchley finds in the Wiltshire and Bath districts are characteristic 
of Chalk. 
Thus it appears that all the above species, although in many districts 
essentially non-Chalk plants, may be associated with highly calcareous as 
well as with more normal loams. Veronica hederaefolia is particularly 
interesting, for on the Cotswolds it is one of the commonest weeds, where 
it generally has a frequency corresponding to a dominant position, yet 
‘ it is absent from chalk and only once dominant on loam ’. 
1 Brenchley, W. E. : (3 a\ (3 b), (3 c). 
