i55 
Brenchley . — The Weeds of Arable Land . III . 
is variable the two species occur pell-mell in various proportions. He also 
concludes that Raphanus is calcifuge and Brassica arvensis calcicolous, but 
this statement is not borne out in its entirety by the present investigations, 
though broadly it meets the case. 
2 . While Poa annua and Anagallis arvensis have a dislike for chalk, 
other plants are always to be found on calcareous land, though they are 
frequently seen on light soils as well. The chief of these are : 
Centaurea Scabiosa 
Papaver Rhoeas 
Reseda lutea 
Silene inflata 
Viola tricolor 
3. Euphorbia exigua and Ranunculus arvensis have always proved to 
be characteristic of heavy land, i. e. heavy loam and clay. 
4. The following species show very striking distinctions in their 
distribution in different districts : 
Bartsia Odontites. Never recorded from chalk in Norfolk or Bedford- 
shire and usually seen on the heavier soils. Characteristic of chalk in the 
West Country and seldom seen on the heavy land. 
Chenopodium album. Bedfordshire. Never recorded from chalk, most 
frequent on sand and light loam. 
West Country. Frequently seen on chalk and clay, but absent 
from sand. 
Norfolk. Usually distributed over all types of soil. 
Myosotis arvensis. Bedfordshire. Found on all soils. 
West Country. Characteristic of chalk land. 
Norfolk. Rare on chalk. 
Ranunculus repens. Rare on chalk in the east, but frequent on calcareous 
land in the West Country. 
Scandix Pecten-veneris . Bedfordshire. Practically distributed. 
West Country. Characteristic of and practically confined to chalk. 
Norfolk. Absent from chalk, and characteristic of clay and loam. 
Relations existing between the Weeds and the Crops. 
After three seasons’ work in the fields it is gradually becoming possible 
to interpret the earlier results in the light of the current year’s work. The 
first impression obtained was that the crop played very little part in deter- 
mining the weed flora, while the nature of the soil practically settled every- 
thing. Leguminous plants proved to be an exception to this rule, presuma- 
bly because they tend to smother out certain weeds owing to their peculiarly 
leafy habit of growth, and also because certain other weeds seem to be 
habitually introduced with the seeds. 
