Habits of Growth. 65 



this sort of weed, being well known and 

 common in many lands, while among our 

 crop plants red clover is our most common 

 biennial. As biennial weeds are repro- 

 duced from seed only, it is evident that any 

 mode of destruction that wall prevent them 

 from producing seed will also in time effect 

 their destruction, but it may take years to 

 accomplish this, as the seeds of this class 

 also have great vitality. Fortunately, how- 

 ever, biennial weeds cannot well resist the 

 destructive effects upon their roots of thor- 

 ough cultivation; hence we find this class 

 of weeds more common in old meadows 

 and pastures, along roadsides, and in waste 

 lands generally, than in fields that are cul- 

 tivated. In areas which cannot be culti- 

 vated, therefore, their destruction is more 

 difficult than elsewhere. To destroy them 

 in these places persistent cutting with the 

 mower, scythe, or spud is the only method 

 that can be adopted ; but it should be borne 

 in mind that with many varieties of bien- 

 nial weeds there is not only a great persis- 

 tency of growth, but also, during the sec- 

 ond year, a great persistency of effort to 

 produce their seeds, even though they are 

 cut off several times during the season. 



