WEEDS OF FARM LAND 



Brassica sp. Charlock. 



Area. 



Lab. House Meadow 

 Barn Field Grass . 

 Geescroft 

 New Zealand I 



II 

 Long Hoos . 



Period under 

 Grass. 

 Years. 



58 

 43 

 32 

 10 

 10 

 o 



Number of 



Seedlings 



from Samples. 



I 

 3 



ii 

 ii 



16 



The number of seeds was not great, but as each charlock 



plant grows large and is very 

 conspicuous, it is probable that 

 quite sufficient would be present 

 to make a good show if the land 

 were again ploughed. As a 

 matter of fact, New Zealand 

 was broken up immediately after 

 the samples had been taken, 

 and the following season an 

 abundance of charlock smothered 

 the field, together with large 

 quantities of ivy-leaved and field 

 speedwell, with poppies locally. 

 The great decrease in the 

 number of live charlock seeds 

 as the period of burial lengthened 

 does not indicate that this parti- 

 cular seed is any better fitted to 

 survive under such conditions 

 than many other species that 

 are less striking in appearance. 

 The Rothamsted records in 

 several cases give details of the 

 weeds that occurred on the 

 fields sampled when they were originally under the plough, 

 and a comparison of these with the seedlings obtained in the 

 pans shows a close resemblance, thus further strengthening 

 the theory that the weeds in the pans had sprung up from 

 seeds that had remained alive though buried for years. The 

 occurrence of seedlings of creeping thistle (Cirsium arvense) is 

 of interest, as fanners often maintain that the seeds of this 

 plant are abortive and never germinate (Fig. 25). 



The reasons why seeds buried in soil should retain their 



FIG. 25. SEEDLING OF CREEPING 

 THISTLE (Cirsium arvense) which 

 came up from Seed Buried in Soil 

 from New Zealand Field at Roth- 

 amsted. 



