POISONOUS AND INJURIOUS WEEDS 107 



occur as well, and this may account for the conflicting opinions 

 as to the poisonous nature of the weed. There can be no 

 doubt, however, that some species of Equisetum are actively 

 injurious to stock, and Equisetum arvense is probably one of 

 them. German feeding experiments have indicated that field 

 horsetail (E. arvense) is harmless to the larger domesticated 

 animals, while the marsh horsetail (R. palustre] is really injuri- 

 ous to cattle. In America, on the contrary, it is stated that 

 R. arvense has proved fatal to horses, especially young animals. 1 

 Complaints of Equisetum poisoning are fairly frequent in the 

 Russian Agricultural Press, horses and cattle suffering more 

 from the effects of eating the plant dried (in hay) than green. 2 

 In feeding experiments dried Equisetum arvense was mixed 

 with hay, the quantity being gradually increased from -J- 

 to 6 Ib. per day. At first the animals preferred it to the 

 rest of their food, but gradually left it alone, and after fourteen 

 days would hardly touch it. At the end of this time symptoms 

 of poisoning were evident, and it was concluded that the weed, 

 to be dangerous to horses, must be present in large quantities, 

 but might then prove fatal. 3 This is corroborated from Canada, 

 as Howitt 4 states that if fed in quantity in hay E. arvense is 

 poisonous to horses. In some parts of England, as at Chedzoy, 

 on Sedgemoor, horsetail has a very bad reputation for causing 

 scour in cattle, but horses and sheep are said to be unaffected 

 by it. As various species are classed under the popular name 

 it is probable that some cause scouring and others do not, 

 which may account for the indifference with which the plant is 

 regarded by farmers in some places and the objection to it in 

 others. Cattle dislike the weed and eat round the clumps in 

 order to avoid it as far as possible. 5 



The presence of Equisetum indicates poor drainage, and if 

 this is attended to by deep ploughing on arable land, and by 

 underdraining grass-land, in addition to keeping the water 

 courses clear, it is not usually difficult to eradicate the weed. 



Meadow saffron or autumn crocus (Colchicum autumnale] 



1 See Long, H. C. (1917), toe. cit. , pp. 84-85, for a fuller account of this work. 



2 Trudy Bjuro po prikladnoj Botanikje, Jan., 1916 ; see your. Bd. Agric., 

 XXIII, p. 278. 



3 " Horse Poisoning by Equisetum arvense " (1912), Kew Bull. Misc. Inform., 

 No. 3 ; see your. Bd. Agric., XIX, p. 229. 



4 Howitt, J. E. (1916), " Weeds of Ontario," Ontario Dept. of Agric., p. 22. 



5 Brenchley, W. E. (1916-17), " West Country Grass-lands," your. Bath 

 and West and Southern Counties Soc., XI, p. 97. 



