154 WEEDS OF FARM LAND 



Some of the discrepancies in the above table are such as 

 might be reconciled or eliminated with a wider range of ob- 

 servations, but a few of the statements are so diametrically 

 opposed to one another that it is difficult to see how they 

 could be made to agree. 



Alopecurus agrestis is peculiarly at home on heavy clay 

 and the heavier soils, so much so that it seems to be character- 

 istic. In the Rothamsted experiments it was only seen once 

 on sand and four times on gravel, out of a total of fifty-four 

 observations, a fact which gives no corroboration to Long's 

 statement that it is a weed of dry sandy soils. 



Papaver rhceas is popularly associated with light soils, and 

 indeed, often occurs so abundantly in such situations as to 

 nickname the whole district, e.g. "Poppyland" in Norfolk. 

 Nevertheless, an unbiassed analysis shows that whereas poppies 

 are often overwhelmingly abundant on some light soils, yet 

 they are universally distributed over nearly all soils, although 

 they are present in smaller quantities on the really heavy 

 types of land. It has already been pointed out that Papaver 

 rhceas was observed as a dominant on every kind of soil except 

 clay and peat, so that there seems to be no justification for 

 Buckman's remark that this species is " a most exact indicator 

 of sandy soil ". As a matter of fact, poppies are impatient of 

 certain types of sandy soil, and the acid sands that bear heavy 

 .crops of spurry rarely carry many poppies, while the chalky 

 sands that are so congenial to the latter are unfavourable to 

 the growth of spurry. 



Long's statement that Rumex acetosella occurs on all dry 

 soils is misleading, as this includes the chalky land which is 

 obnoxious to the species. The writer's observations go to 

 show that sheep's sorrel is characteristic of light and sandy 

 land, but that it is seldom seen on chalk, so much so that the 

 plant is regarded as one of the few " indicators " of acid soil. 

 Being shallow rooted it may be found as a denizen of a very 

 thin layer of sour land overlying chalk, as happens in the 

 " bake " on the top of some of the Wiltshire Chalk downs. 



Spergula arvensis is another plant that indicates a deficiency 

 of chalk, and again it is misleading to describe it as occurring 

 on all soils. The plant is still more characteristic of sand and 

 very light soil than the sheep's sorrel, and even when it puts 

 in an occasional appearance on heavier land it is usually very 

 scarce. Its dislike of chalk is so marked that although it has 

 been noted 218 times it has never once been observed on 



