THE WHOBLED MILKWEED AS A POISONOUS PLANT. 39 



stroying it, wherever it is common on range or trail, will solve the 

 poison danger for the season, often saving thousands of dollars. 

 iWhere the milkweed is growing in a meadow it should be carefully 

 culled out by hand, for hay containing any considerable quantity of 

 it is deadly to animals that eat it, and the hay therefore is worthless 

 for feeding purposes. 



PREVENTION BY CARE OF STOCK. 



While it is not true that animals instinctively avoid injurious 

 plants, it is true that they seldom eat them by choice. In the case 

 of the whorled milkweed they seem to have an actual dislike of the 

 plant, and eat it only when forced by hunger. This can be seen in 

 many small pastures in western Colorado where whorled milkweed 

 is abundant but forage is also plentiful, and the animals avoid the 

 milkweed. Poisoning occurs when animals are confined in a pasture 

 with little else to eat, when they are driven in a more or less hungry 

 condition along trails where there is milkweed, or when they are on 

 overgrazed ranges. It is evident that if the herder recognizes the 

 dangerous character of the plant and uses suitable care, most losses 

 will be avoided. 



Care also should be taken, if hay from a milkweed region is used, 

 to see that it contains no considerable quantity of the weed. If the 

 weed is mature, as is generally the case, it is readily recognized by 

 the pods. 



SUMMARY. 



The whorled milkweed growing in Colorado, Utah, New Mexico, 

 and Arizona has been proved to be exceedingly poisonous. 



The weed has been identifiied botanically as Asclepias galioides. 

 In previous publications it has been cited as Asclepias verticillata. 



The plant is poisonous to horses, cattle, and sheep, but most of the 

 reported losses have been of sheep. 



The most marked symptoms are the violent spasms. The autopsies 

 and microscopical examinations show congestion of the peripheral 

 blood vessels, the congestion being especially marked in some glandSj 

 the lungs, and the central nervous system. 



The chemical examination of the plant, while incomplete, has dem- 

 onstrated the existence of definite toxic compounds, part of which 

 are glucosidal in nature. The plant contains also a minute quantity 

 of nontoxic alkaloid. 



There is no medicinal remedy which gives satisfactory results. 

 Reliance must be placed on the destruction of the plant and such 

 care of stock as will prevent hungry animals from coming into con- 

 tact with masses of the weed. 



