Extirpation of IVeeds. 245 



abound most in wet seasons on moist lands ; and being hardy annuals, producing 

 a plentiful crop of seeds, are apt to shew themselves in crops of grain : to be de- 

 stroyed by fallowing, by draining, and by rooting out. 



19. Knott grass (Polygonum avicularej ; a trailing plant ; flourishes most by road 

 sides and on gravel walks : out of the smothering of crops, very prolific in seeds, 

 which are eaten by small birds. 



20. Black bindweed, bearbind (Polygonum convolvulus) ; a parasitical plarrt, 

 twining round any thing it can lay hold of; very productive of seeds, which, being 

 angular, are not easily separated from grain in dressing or winnowing. This plan 

 is not much approved by the Staffordshire or Shropshire farmers, who are very 

 cautious of sowing it. It is nearly allied to the buckwheat (Polygonum fagopyrum), 

 to which it is preferred by Dr. Withering, in the following words : " the seeds are 

 quite as good for use as those of buckwheat, are produced in greater quantity, and 

 the plant bears cold better." 



21. Knawell (Sclerantbus annuus zndperennis) ; a diminutive plant, but prolific 

 ill seeds, and of vigorous growth ; have often found it on a piece of poor thin soi 

 on my farm when in tillage, but do not think it very pernicious: it may, probably 

 be weakened or destroyed by an early spring working of the land when in fallow. 



22. Bladder campion (Cucubalus behen) ; common in wheat and barley crops, 

 and growing in tufts, many stalks from each root, which, when the case, should be 

 rooted out by hand : it is a perennial plant, and has the habit of increasing from 

 its roots. 



23. Cockle (Agrostemma githago), a luxuriant, vigorous, annual plant ; perfect- 

 ing many seeds, and drawing much from the soil : care should be taken not to sow 

 this injurious weed. The seeds are so large that they cannot all be dressed from 

 the grain, the plant should therefore be plucked out by hand before the seeds ripen. 



24. Red and white campion (Lychnis dioicaj, perennial weeds, growing in hedges, 

 corn-fields, and pastures; to be weakened or destroyed by well managed fallows. 



25. Mouse-ear (Cerastium arvense) has somewhat the habit of chickweed, but 

 of a duller complexion ; frequent amongst corn and in pastures. 



26. Corn spurrey, or yarr, (Spergula arvensis); frequent in corn-fields, not very 

 bulky or luxuriant, but quick and tenacious of growth, and producing seeds plen- 

 tifully: as it is of humble growth, I have never observed it to be very injurious to 

 a crop; but Dr. Anderson observes, that in Aberdeenshire it is a pernicious weed. 



