142 Brenchley. — -The Weeds of Arable Land. III. 
very variable in nature and texture even within very circumscribed 
areas, gravel, sand, loam, and clay occurring in. close proximity in 
many places. In some districts the Boulder Clay is very chalky in nature 
owing to the grinding up and mixing of the underlying chalk strata with the 
glacial deposits. In some parts of West Norfolk these underlying strata 
themselves crop out, so that it was possible to get some insight into the 
weed flora of the Chalk, Gault, and Lower Greensand in addition to that of 
the heterogeneous glacial soils. 
In the course of the season’s work the following places were taken 
as centres, and the weed flora was investigated for some miles round : 
North Walsham, Aylsham, Hargham, Bressingham, Harleston, Field Dal- 
ling, Swaffham, Marham, Snettisham, and Sandringham. The plan of 
campaign was the same as in the two previous years, and the relative 
prevalence of the weeds was again notified as — 
(1) Dominant. 
(2) Sub-dominant. 
(3) Distributed. 
(4) Occasional. 
(5) Scarce. 
During the season’s survey about 480 fields were visited, yielding 
a harvest of 162 species of weeds, belonging to 104 genera. Of these 
36 species, representative of 32 genera, were each seen once or twice only. 
The total number of species and genera occurring was far in advance 
of those from Bedfordshire and the West Country, though the number seen 
once or twice only was practically the same in each of the three districts. 
The strictness with which the various plants keep to their several 
habitats of field and hedgerow is most remarkable. A very few species, 
such as Scabiosa arvensis and Centaurea nigra , are denizens of both 
habitats, but otherwise it is very rare to find any incursion from one to 
another, even at the extreme edges of the fields. As heretofore, only 
the plants growing in among the crops were considered as weeds. 
The chief species of weeds, with their habitats and relative dominance, 
were as follows : 
Ranunculaceae. Ranunculus arvensis. Confined to the heavier loams 
and clay. Seldom seen, never dominant. 
Ranuncidus repens. Distributed over all soils, but seldom seen on 
chalk. Once dominant on heavy loam, usually distributed. 
Fapaveraceae. Papaver Argemone. Only occasionally seen, on light 
loams. Never in any quantity. 
Papaver Rhoeas. One of the commonest weeds. Chiefly on sand, 
very frequent on light loams and chalk. Often dominant. 
