H2 WEEDS OF FARM LAND 



serious internal derangements if too many are present in the 

 oats fed to stock. 1 In Belgium, hogweed (Heracleum sphon- 

 dylium) is supposed to have caused " Panaisie," a kind of 

 erysipelas induced if the plants are rooted up when they are 

 covered with dew. No harm results when hogweed is pulled 

 later in the day, 2 because then the dew, in which it is suggested 

 that an irritant essential oil is dissolved, has been dissipated 

 by the sun. 



Occasionally mechanical injury is caused by local irritation 

 due to very rough or sharp weeds or by the accumulation of 

 indigestible masses in the alimentary canal. Huffcaps (Aira 

 ccespitosa] is an exceedingly coarse and rough grass and rasps 

 the mouth badly, and in places where it occurs a clause 

 is inserted in many leases to the effect that the land must 

 be kept clear of it by cutting or otherwise. 3 The sharp 

 awns of certain grasses, as wild barley and brome, tend to pene- 

 trate the gum and break off, giving rise to considerable inflam- 

 mation, and if the heads are swallowed they may accumulate or 

 " ball " in the stomach of the animal. The fibres of shepherd's 

 purse and the much branched chickweed are liable to cause 

 trouble in the same way if they are eaten too freely. 



(B) WEEDS THAT INJURIOUSLY AFFECT FARM PRODUCTS. 



The milk of cows and the flesh of stock is liable to become 

 tainted if any strong smelling or strong tasting plant is 

 included in the animals' food, and many complaints of un- 

 pleasant flavours have been traced to this source. There are 

 not a large number of weeds that are proved to taint farm 

 products, but some of these have been in bad repute from early 

 days. In 1789 Adam 4 included dyer's weed (Reseda sp.\ darnel 

 (Lolium temulentum), cow-wheat (Melampyrum j/.), melilot 

 (Melilotus sp.) y and crow garlic among the weeds that spoil farm 

 products, and most of these had been known for long before. 



Crow garlic (Allium vineale] (Fig. 34) and ramsons (A. 

 ursinum) (Fig. 35) bear the worst reputation for tainting milk 

 and for injuring wheat and flour. Crow garlic is difficult 

 to distinguish among grass until it flowers, as the leaves are 

 very narrow, so that suspected pastures should be very carefully 

 examined before stock is turned in in the spring. Although 



1 Henslow, G. (1901), loc. cit., p. 141. *Ibid., pp. 99-100. 



3 Brenchley, W. E. (1916-17), "West Country Grass-lands," ibid., p. 97. 

 4 Adam, J. (1789), " Of Weeds," " Practical Essays in Agriculture," II, pp. 

 173-198. 



