176 WEEDS OF FARM LAND 



sometimes " fatting" and " non-fatting," i.e. while the former 

 is excellent grazing pasture and fattens sheep rapidly the 

 latter-is of little use except for carrying store beasts. A com- 

 plete botanical analysis of the herbage reveals no variation in 

 the species present that would account for such a difference, 

 so that the same combination of plants is far more valuable 

 in the one case than in the other. Some grasses, as Yorkshire 

 fog and tall oat, tend to grow rank and coarse under favour- 

 able conditions and are then rightly considered as weeds, but 

 nevertheless the best pastures and meadowland of the highest 

 feeding value usually contain one or both of these grasses, the 

 proportion of Yorkshire fog often being quite appreciable. 



On account of this necessary reservation, therefore, a weed 

 of grass-land may be considered to be any plant that is in 

 itself useless or injurious (a mere cumberer of the ground), or 

 any plant that in the case in question is of low feeding value 

 and by its abundance or rank growth tends to crowd out and 

 supplant other species that under the same circumstances 

 would provide far more nourishment to the stock feeding 

 thereon. As high feeding value is more usually associated 

 with certain grasses and leguminous plants than with miscel- 

 laneous species, it often happens that the most valuable 

 pastures and meadows are stocked almost entirely with the 

 former while the inferior grass-lands show a large percentage 

 of the latter in the composition of their herbage. 1 As a matter 

 of fact, it is usually fairly easy to decide whether a certain 

 species is to be considered as a weed or as a useful plant on a 

 particular area of grass-land. Various rank and tall-growing 

 plants, as thistles, woodwax, nettles, chervil and docks, do not 

 under any circumstances enter into the legitimate composition 

 of the herbage and are always to be regarded as weeds. Run- 

 ning plants, such as couch-grass (Agropyron repens], creeping 

 buttercup (Ranunculus repens), bindweed (Convolvulus arvensis), 

 and bent grass (Agrostis spp.}, which tend to cover large areas 

 of ground with their matted stems and roots, do much damage 

 to grass-land, and certain rosette plants that lie very close to the 

 ground, e.g. mouse-ear hawk weed (Hieracium pzlosella), suffo- 

 cate all other plants growing under the spread of their leaves. 

 All these must be regarded as pernicious and to be removed 

 whenever possible. Poisonous or injurious plants, such as 

 meadow saffron, purging flax, hemlock, and garlic, are not to be 



1 Armstrong, S. F. (1907), " Botanical and Chemical Composition of the 

 Herbage of Pastures and Meadows," Jour. Agric. Sci., II, pp. 283-304. 



