POISONOUS PLANTS 227 



ERICACEJE. 



The poisonous members of this family likely to be found 

 in Great Britain are the exotic shrubs, Rhododendron^ Azalea, 

 and Kalmia, or laurel ivy, widely cultivated for ornamental 

 purposes. 



Rhododendron appears to be often eaten freely by cattle 

 and sheep, and several cases of poisoning by it are on 

 record. In America R. californicum is native on the Pacific 

 Slope from San Francisco to British Columbia, and has 

 been reported as poisonous to sheep in Oregon, whilst 

 R. maximum, native in 'the Allegheny Mountains, is also 

 fatal to stock. 



Active PFineiple. — Our chemical knowledge of rhodo- 

 dendron poison is not complete. The leaves contain a 

 tannin, resolved by acids to the yellow-red rhodoxanthine, 

 and it is noteworthy that a reddish tint has been observed ^ 

 in the milk of a cow poisoned by this plant. The leaves 

 also contain a bitter yellowish-brown resin, and contain the 

 active principle andromedotoxin. 



Symptoms. — After ingestion of rhododendron leaves, 

 cattle and sheep manifest intense pain, diarrhoea, and dis- 

 comfort, gritting the teeth, salivating, and frequently vomit- 

 ing. There is suppression of lactation, trembling, and 

 spasms, vertigo, loss of power, and death. 



Eecent cases of rhododendron poisoning of cattle are 

 those noted in references 1, 2, and 4. They agree in all 

 the salient points, serve to emphasise the generality of 

 actual vomition under the influence of this poison, and 

 also well display the nervous symptoms. 



One of the earliest observations '' is on calves, and is 

 remarkable, in that no diarrhoea or actu^il vomition was 

 observed, but there was the same disinclination to move, 

 staggering, and reeling gait. 



In sheep ^'^'^ there are similar symptoms, but actual 

 vomition does not seem so general as with cattle. 



