568 



MANUAL OF POISONOUS PLANTS 



Distribution. Western Minnesota, Western Iowa, and Missouri to Texas, 

 and New Mexico, north to British Columbia, and northwest territory. 



Poisonous properties. The stemless loco weed is one of the most 

 characteristic loco weeds of the West. The symptoms of poisoning 

 are similar to those produced by the woolly loco weed described at 

 length elsewhere. The poisonous substance has not been isolated. 

 An alkaloid, however, has been reported by Prof. Prescott. Chesnut 

 and Wilcox, in speaking of the history of the loco poisoning in Mon- 

 tana, say that in Colorado the plant which is most commonly known as loco 

 weed is Astragalus mollissimus. In Montana, on the other hand, the plants 

 most generally called loco weeds by the stockmen are species of Aragallus 

 {Orytropis). "The species which is most concerned in causing the loco disease 

 in Montana is the Aragallus spicaius and is closely related to Oxytropis Lamberti," 

 Stockmen are of the opinion that a condition somewhat similar to loco poisoning 

 may be brought about by eating undue quantities of alkali soil. 



a c 



Fig. 313. Stemless or Purple l^oco Weed a, Plant. 

 Dept. Agr. 



b. Seed pods, c, Seed. U. S. 



It should be stated also that the larvae of sheep bot flies, which are frequently found 

 in the frontal sinuses of the head, can not possibly be considered the cause of the nervous 

 symptoms characteristic of the ioco disease, for the reason that these larvae are not found 

 in greater abundance in locoed than in healthy sheep. For the same reason the presence 

 of the common tape vform ^Taenia serrata) in the small intestines and bile duct of sheep 

 can not be considered as the cause of the locoed condition. These worms are almost 



