140 WEEDS OF FARM LAND 



Heavy loam provides a rather more congenial habitat for 

 V. tournefortii than clay, the plant is as fully at home on 

 medium loam as on the heavier soils, and it exhibits some 

 dislike of chalky soil. This speedwell is occasionally dominant 

 on various soils, usually on heavy loams, but probably as time 

 goes on it will become much more prevalent and widespread 

 if its progress continues to be as rapid as it has been of late 

 years. 



Horsetail (Equisetum arvense) and corn mint (Mentha 

 arvensis] are similar in distribution to the large-flowered 

 speedwell. Horsetail is often dominant on various soils, 

 chiefly on clay and medium loam, but it would probably 

 dominate to a much greater extent if it were allowed to. It 

 is, however, such a troublesome pest that special efforts are 

 directed towards its eradication, and the success of these 

 efforts is shown by the number of fields from which the 

 weed is recorded as scarce. The long underground parts 

 enable the plant to spread over wide areas, and it is difficult 

 to clear the soil of the weed when once it has obtained a firm 

 hold, especially on heavy land. It is abundant at Rothamsted 

 on the unmanured plot of Broadbalk wheatfield. 



Orache (Atriplex patula] is essentially a weed of heavy 

 and medium soil, although when it does occur on the light 

 soil it is often very plentiful and even dominant. Many 

 farmers fail to recognise this weed, as in some ways it closely 

 resembles fat hen (Ckenopodium album), especially in the early 

 stages of growth, and the idea is prevalent that the low- 

 spreading plant of orache is merely fat hen that has been cut 

 down or has met with other injury during growth and so has 

 spread out instead of growing into the tall form characteristic 

 of the Ckenopodium. Fat hen, however, is much more widely 

 distributed, and does not show the same preference for heavy 

 and medium soil as orache. Orache is not very often domi- 

 nant considering how often it occurs, but it is usually present 

 in some quantity. The seeds are very tenacious of life and 

 can survive burial in the soil at considerable depths 1 for 

 many years, starting into active growth if ever conditions 

 become favourable. 



Nipplewort (Lapsana communis] is uncommon and scarce 

 as an arable weed. It is very rarely present in any appreci- 

 able quantity, though it was once seen dominant at Staythorpe 



1 Brenchley, W. E. (1918), " Buried Weed Seeds," Jour. Ag. Sci., IX, 

 pp. 1-31. 



