POISONOUS AND INJURIOUS WEEDS MI 



underground stems, and possibly these are the only parts of 

 the plant that are actually poisonous as it is said that the 

 stems and leaves can be eaten in quantity with impunity. 1 

 The poison is very rapid in its action, the first symptoms ap- 

 pearing in about twenty or forty minutes, and death resulting 

 if a fatal dose has been swallowed. Wherever water hemlock 

 is known to occur the plants should be grubbed out and burned ; 

 great care being taken not to leave any portions of the rhiz- 

 omes lying about where animals can get them. The pulled 

 plants should not be left in the water as the toxic principle, 

 cicutin, dissolves out and contaminates it, thus giving rise 

 to another source of trouble. 2 



In addition to the above outstanding weeds there are a 

 few which are certainly poisonous or otherwise harmful, but 

 which are only locally or occasionally present in sufficient 

 quantity to cause trouble. 



Sheep's sorrel (Rumex acetosella) is charged 3 with having 

 poisoned a horse and sheep which browsed upon it when the 

 fruit was ripe and full of seeds, with fatal results to the horse. 

 The nature of the poisonous principle, if any, is not known, 

 unless the toxic action was due to the acid oxalates that are 

 present in the plants. Spurges (Euphorbia spp.~] are usually 

 avoided by stock, but if eaten are harmful as the juice is acrid 

 and the seeds contain an extremely purgative oil. Stagger 

 weed (Stachys arvensis] seldom occurs in any quantity in Eng- 

 land, but in the Dominions it is reported as causing serious 

 trouble among cattle. 4 It is a weed of damp places and may 

 be eradicated by draining. Black nightshade (Solanum nig- 

 rum] sometimes does mischief, and Barthe states that it is 

 poisonous in warm and temperate regions, but loses its poison- 

 ous properties in the cold northern regions. 5 



Without being actually poisonous some weeds may cause 

 trouble if they are eaten or handled. Broomrape (Orobanche 

 minor) has been found to produce colic in animals fed on 

 clover, in which it grows plentifully, while the seeds of black 

 bindweed (Polygonum convolvulus] may, after some time, cause 



1 Fleming, C. E. (1918), " Range Plants Poisonous to Sheep and Cattle in 

 Nevada," Agric. Exp. Stat., Univ. of Nevada, Bull. No. 95, p. 23. 



1 Smith, J. D. (1917), " Weeds of Alberta," Bull. No. 2, Province of Alberta, 

 Depart, of Agric., Seed and Weed Branch, p. 98. 



J Henslow, G. (1901), loc. cit., p. 142. 



4 Maiden, J. H. (1916), " Asphodelus nstulosus and Stachys arvensis: 

 Harmful Weeds in New South Wales," Aerie. Gas., Ntw South Walft, 

 XXVIII, pp. 335-338. 



8 Barthe, L. (1918), " Toxicologie chimique," p. 518. 



