CHAPTER 8 

 MISCELLANEOUS DICOTYLEDONOUS PLANTS 



St. John's Wort (Hypericum perforatum) . This is a perennial, much- 

 branched herb with sessile, elliptical leaves having punctate oil glands 

 with a few purple-spotted ones. The yellow flowers are found in cymose 

 clusters. The stamens are numerous, but arranged in five clusters 

 (pentadelphous) . 



Symptoms. White-skinned cattle and sheep eating St. John's wort 

 show an acute inflammation of the white skin, although dark skin remains 

 unchanged. An entire herd of Holstein cattle has been seen with all the 

 white skin hanging in sheets, while the black skin remained intact. The 

 ears at times in sheep are greatly swollen, and if the eyes are effected total 

 and permanent blindness may develop. If the animal is entirely white 

 death may follow, as with extensive burns, the inflammation extending 

 over three-fourths of the skin area. This plant is a decided hindrance to 

 grazing in the French colonies of northern Africa, as in Tunis. Exposure 

 to sunlight is necessary to the development of the curious symptoms of 

 the disease, and animals rapidly recover, if they are protected from the 

 direct rays of the sun, for it appears, as if the herb sensitizes the skin to 

 the invisible chemical rays (the ultra violet) of the solar spectrum. Deaths 

 of horses poisoned by this plant have been reported at Norwood, Maryland 

 within a few years. As the herb preserves all its activities when dried, 

 it may cause trouble, if fed in hay to horses. The treatment consists 

 in blackening the white skin with a mixture of charcoal, linseed oil and 

 lime water. This is applied with a brush and the animals are kept from 

 sunlight and from eating St. John's wort. Cows pastured in a field with 

 this plant, if white-nosed animals, have their udders crowded with erup- 

 tions due to contact with the St. John's wort especially on dewy mornings. 



The symptoms other than those reported above are dullness, a sinking 

 of the head, loss of appetite,, slackening of the pulse and respiration, dila- 

 tion of the pupils, defective sight and purple lips. 



Poisonous Principle. The oil, which is responsible for the poisoning 

 of the animals, is located in little glandular areas which give the leaf a 



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