PREFACE. 



EVERYONE who cultivates the soil, whether on the farm 

 or garden, is perforce interested in weeds, for their 

 absence or presence amongst the crops has much to do 

 in' determining the relative success or failure of the 

 undertaking. A very great deal has been written on 

 the subject, but the information is widely scattered 

 throughout the literature of agriculture and botany. In 

 this country, at least, very few efforts have hitherto 

 been made to gather up and correlate this varied know- 

 ledge, thus rendering it accessible to those most inter- 

 ested. Furthermore, it is only of recent years that 

 definite attempts have been made to work out the quanti- 

 tative and qualitative relations between weeds, the soils 

 on which they grow and the crops with which they are 

 associated. In this respect the conclusions so far drawn 

 can only be regarded as tentative, subject to modification 

 and revision as more data become available. It has 

 seemed justifiable, therefore, to attempt to set forth the 

 present position of affairs, in order that future attacks on 

 the weed problem may be more co-ordinated, and that 

 valuable time and labour may be utilised to the best 

 advantage. 



The original investigations embodied in the follow- 

 ing pages owe much to the cordial assistance afforded 

 by the many landowners and farmers whose land has 

 been utilised for the purpose. It is impossible to record 

 each individually, but my special thanks are due to Pro- 

 fessor T. B. Wood, Mr. Spencer Pickering, Mr. E. S. 

 Beaven, Mr. E. E. Stokes, and Mr. J. H. Burton, all 



