WEEDS OF ARABLE LAND 59 



it produces an abundance of seed, which ripens quickly, 

 and has a wonderful vitality which enables it to lie for 

 many years in the soil uninjured, and later such buried 

 seed may germinate when brought to the. surface. 

 Further, the seeds ripen before cereal crops are cut, 

 and this affords an opportunity for the perpetuation of 

 the weed, which 

 is only overcome 

 with the greatest 

 difficulty. If land 

 be laid down to 

 pasture, Charlock 

 will disappear, 

 being exclusively 

 a weed of culti- 

 vated land ; but 

 should an old pas- 

 ture be ploughed, 

 Charlock is al- 

 most certain to 

 spring up. Ex- 

 periments con- 

 ducted by Pro- 

 fessor Peter at 

 Got tin gen have 

 shown l that the 

 seeds of Charlock 



. . ,. FIG. ii. Charlock (Sinapis arvcnsis L.), x \. 



can retain their 



vitality or germinative capacity for forty years, espe- 

 cially when they lie at considerable depths in the 

 soil. 



Losses due to profuse growth of Charlock and allied 

 species (described below) have been found in Germany 

 to be very great. The following examples may be 



1 Deutsche Landw. Presse, July 24, 1909. 



