394 



MANUAL OF POISONOUS PLANTS 



Fig. 175. Showy Lady Slipper 

 {Cypripedium hirsututn). A plant 

 thought to cause dermatitis. C. M. 

 King. 



Fig. 176. Flower of another orchid (Habenaria). 



Showy Lady Slipper and became poisoned very Tnuch as if it were by poison 

 Ivy. Prof. Chesnut in referring to the poisoning from these plants says: 



The poisonous character of these plants was not suspected prior to 1875, when 

 Prof. H. H. Bahcock, of Chicago, who had annually been suffering, supposedly from 

 recurrent attacks of ivy (Rhus) poisoning, discovered that the affection was most probably 

 caused not by the ivy, but by the two species of Lady's Slipper named above (C. parvi- 

 florunt, var. pubescens and C. hirsutum) instances were afterward reported, but the 

 facts were not positively ascertained until 1894, when an investigation was made by 

 Prof. D. T. MacDougal of the University of Minnesota. It was discovered that these 

 plants are provided with glandular hairs which cover the surface of the stem and leaves 

 and contain a poisonous oil which is especially abundant at the fruiting season. Its 

 action on the skin is very similar to that of toxicodendrol, the active constituent of poison 

 Ivy (,Rhus Toxicodendron), but its exact chemical nature could not be ascertained on 

 account of the small quantity obtainable. Experiments with the stem and leaves upon 

 individuals showed that over half of them were affected by the first two species, and that 

 the last was also poisonous, but in a minor degree. No accidental cases have been recorded 

 against it. No specific antidote has been suggested. 



