66 PASTURE AND RANGE. 



PEA FAMILY Leguminosae. 



STEMLESS LOCO WEED Oxytropis spp. DC., also known as 



Aragallus. 



Other Common Names : Loco Weed, Crazy Weed, Loco 

 Vetch, White Loco. 



For many years stockmen of the west have been suffer- 

 ing great losses from the disease known as "Loco." Sev- 

 eral agencies have at various times been held 

 The Loco responsible for the trouble. One opinion was 



Tli con GA 



that animals not regularly supplied with salt 

 acquired the disease from eating the alkali so common 

 in certain soils of the plains. This idea has been shown 

 to be erroneous since cases of "locoing" have become 

 known on ranges where the alkali could not be obtained. 

 Various plants were also blamed for the trouble and in- 

 vestigation has proved that this is correct, there being 

 now several distinct species of recognized Loco weed. 



The disease takes a peculiar course, not unlike the 

 development of the drug habit in human beings. Horses 

 and sheep are the animals usually affected, but cattle also 

 become locoed in some cases. Animals may be pastured 

 for years on ranges where the Loco Weed is found and 

 show no ill effects, as they ordinarily avoid it. When one 

 of them acquires the taste, however, it develops a crav- 

 ing for the weed and hunts it incessantly. Sheep acquire 

 the habit by imitation, and so it is important to remove 

 all locoed animals at once from the flock. 



In chronic cases of locoism an immunity is developed, 

 so that increasing quantities are necessary to produce 



characteristic symptoms. In such cases there 

 Locoism * s a continual craving for Loco Weed, the 



animal nervously searching it out and feeding 

 on it. Locoed sheep become more and more emaciated 



