142 POISONOUS PLANTS 



Polygonums are bitter, rich in tannin ; but they 

 are not otherwise known to be poisonous. 



Dock {Rumex, sp.). — Those species which have 

 an acid flavour are called Sorrels. Of these we 

 have two species, the common Sorrel (^R, Acetosci) 

 and the Sheep's-sorrel {R. Acetoselia, Fig. 36). 

 They are both dioecious, the male flower having a 

 calyx of six sepals and six stamens ; the female 

 has a similar calyx, with a pistil carrying three 

 feathery stigmas (see figure on the right) adapted 

 to wind-pollination. 



The acidity is due to the presence of binoxalate 

 of potash, sold as salts of lemon or of sorrel ; and 

 in that form it is very poisonous. It is useful for 

 removing the stains of ink (made from oak-galls) 

 from linen. 



The little plant known as Sheep's-sorrel is 

 common in sandy districts, heaths, etc. It is called 

 by this name under the impression that sheep will 

 eat it with avidity ; but veterinary doctors charge 

 it with having poisoned both horse and sheep 

 which browsed upon it when the fruit was ripe 

 and full of seeds. Most serious disorganizations 

 coupled with internal inflammation and finally death 

 are described of the horse ; but at present chemists 

 have not tried to discover if the Sheep-sorrel's has 

 any poisonous properties at all, beyond its acidity. 



Instances of poisoning by the common Sorrel {R. 

 Acetosd) have usually been only with children who 



