INTRODUCTION ix 



cases were purely the result of bad farming, weeds 

 are still far more plentiful than they ought to be. 



An important point should be emphasised. Al- 

 though, for example, the Creeping Thistle may be 

 almost or quite eradicated on a given farm by the 

 methods mentioned at pp. 86 and 180, yet its growth in 

 the future is unfortunately not prevented, for fresh seed 

 may blow in from beyond the boundary hedge. For 

 farms to be kept free from many I had almost 

 written all weeds, farmers must work together. There 

 is every reason why farmers should combine to 

 exterminate weeds by tillage and other operations, 

 including the cutting of weeds on waste land and 

 roadsides, and also to ensure purity in the supply of 

 farm seeds. This matter might well be taken up in 

 their own neighbourhood by the members of chambers 

 of agriculture, farmers' clubs, and agricultural societies. 



In the preparation of this volume the fullest 

 advantage has been taken of the information con- 

 tained in a large number of other works, and an 

 endeavour has been made to give due acknowledg- 

 ment in every case. In describing the various plants, 

 Hooker's Student's Flora of the British Islands and Johns' 

 Flowers of the Field have been especially utilised. The 

 Bibliography at p. 372 will indicate the extent of the 

 literature consulted. 



I desire to make the fullest acknowledgment of the 

 assistance of Professor Percival, who not only read the 

 major portion of the manuscript, but the whole book 

 in proof, making many useful suggestions for its im- 

 provement. In addition, Professor Percival has written 

 the notes at pp. 4348 on the destruction of weeds by 

 chemical means; those at pp. 368-371 on the weed 

 seeds found in commercial samples of clover and grass 

 seeds, and on purity and germinating capacity ; those 



