ARABLE WEEDS. ASSOCIATION WITH SOILS 149 



more uncommon weeds, being much less frequent than its 

 ally C. nigra. Usually it is not present in any abundance, but 

 it was once seen dominant on sand in Norfolk. 



Poor-man's-weather-glass or pimpernel (Anagallis arvensis) 

 is one of the more insignificant weeds which are fairly wide- 

 spread but rarely occur in any quantity. Nevertheless, it is 

 in no danger of being overlooked as it attracts much interest 

 and attention from the fact that it is said to close on the 

 approach of rain, thus providing a useful weather glass for 

 country folk. Very occasionally it is present in such abund- 

 ance as to be dominant, and it has been found so both on 

 heavy clay.and chalky loam. 



Hog weed (H eracleum^ sphondylium) is not very common as 

 an arable weed, as it much prefers the hedgerow for its habitat. 

 It never dominates in the fields and is frequently represented 

 by solitary individuals, interlopers that have wandered out 

 from their normal position in the hedges. 



A few of the more common weeds, such as fumitory, 

 campion, field pansy, are not quite as closely associated with 

 chalky soil as those described above, though the preference is 

 still very marked. 



Fumitory (Fumaria officinalis] is ephemeral in nature, 

 and disappears from the fields at a comparatively early date, 

 so that it may be more abundant in reality than the figures 

 indicate. It is quite frequently dominant, and still more often 

 scarce, but both these observations may need to be modified 

 in consideration of the fugitive nature of the species. As a 

 matter of fact Fumaria offidnalis includes a number of species 

 which have not been distinguished in the field, and some 

 of these are more ephemeral than others, so that the records 

 obtained for fumitory in the later months of the season 

 are largely dependent upon the particular species occurring in 

 the districts examined. 



White campion (Lychnis vespertind) is very widely scattered, 

 but it is seldom present in any amount, and indeed is scarce 

 in two out of every five times it occurs. It is quite probable 

 that most of the seed is introduced with clover and other small 

 crop seeds, and this would largely account for the widespread 

 distribution and for the fewness of the plants found. 



Field pansy ( Viola tricolor] is also commonly found in 

 small quantities, and was only once seen dominant on gravel 

 in Nottinghamshire. 



Red bartsia, tall buttercup, dandelion, and round-leaved 



