The Weeds of Arable Land in relation to the Soils 
on which they grow. II. 
BY 
WINIFRED E. BRENCHLEY, D.Sc., F.L.S. 
Lawes Agricultural Trust , Rothamsted. 
URING the season of 1910 an investigation was carried on in certain 
JLJ parts of Bedfordshire to determine the relation between the weeds of 
arable land, the crop grown, and the soils upon which they grow. 
It was recognized at the outset that the results must be regarded as 
tentative in nature until confirmatory evidence was obtained from similar 
work carried out in other parts of the country, on soils both of the same 
and different geological derivation. Consequently in 1911 the field of 
investigation was transferred to certain parts of Wiltshire and Somerset, 
to districts round Warminster (Upper Greensand), Shrewton (Chalk), and 
Bath (Clay). In that part of the country a large number of geological 
formations crop out within a comparatively short distance, but attention 
was confined to two or three main types of soil. 
In the area investigated no sand was available to compare with 
the Lower Greensand of Bedfordshire, the soils of the Upper Greensand 
being generally rather heavy. In place of the Oxford and Gault clays 
(here only represented by pasture), which are non-calcareous in nature, the 
calcareous clays of the Oolite and Lias series came under consideration. 
The working plan adopted was the same as in 1910 ; the areas were 
characterized by the comparative absence of hedges, which greatly facilitated 
the work. 
The relative prevalence of the weeds was again noted as : — 
(1) Dominant. 
(2) Sub-dominant. 
(3) Distributed. 
(4) Occasional. 
(5) Scarce or rare. 
During the season’s survey 106 species of weeds were met with, repre- 
senting 74 genera. Of these 29 species, representative of 26 genera, were 
[Annals of Botany, Vol. XXVI. No. Cl. January, igia.] 
