BULLETIN 800, U. S. DEPARTMEN^ OF AGRICULTTIRE. 



1 



poisoning in western Colorado, and described experiiiients in feed- 

 ing slieep and rabbits which demonstrated the poisonous character 

 of the plant.^ 



In preceding years, however, the Department of Agriculture had 

 received many reports of losses of live stock from milkweed. In 

 most cases the species of plant which caused the trouble was not 

 indicated and the reports were so indefinite that the evidence was 

 not considered strong enough to warrant the addition of the plant 

 to the list of stock-poisoning plants. The reports came from not 

 only Colorado but also from New Mexico, Arizona, California, and 

 Oregon. In 1902, J. C. Johnson, of Higbee, Colo., reported the loss 

 of horses from Asclepias verticillata. 



In October, 1909, Dr. W. E. Howe, inspector in charge of the 

 Denver district, received from Dr. S. C. Babson details of heavy 

 losses of sheep in the neighborhood of Montrose, Colo. The losses 

 were said to have been due to Asclepias verticillata, inasmuch as the 

 animals had fed extensively on the plant and it was found in abun- 

 dance in the stomach contents. Post-mortem examinations were 

 made, and he reported as the only lesion " pale heart muscles, ex- 

 cessive amount of pericardial fluid, and acute inflammation of the 

 outer covering of the surfaces of the brain." 



A similar report was made by Dr. Babson to the chief of grazing, 

 Forest Service, Denver, Colo. He said that the plant grew on the 

 banks of irrigation ditches and that it had been traced from the 

 beginning of the Montrose and Delta Canal to the California mesa. 

 He stated, however, that the plant had leaves 3 or 4 inches long 

 and in pairs. From the description it was assumed that the plant 

 had been wrongly determined and that probably the species he had 

 in mind was Asclepias speciosa. Some experimental work was under- 

 taken in regard to Asclepias speciosa without any definite results. 



The attention of the Washington office was again called to the 

 matter by a letter from L. F. Kneipp, district forester, who reported 

 losses of stock from Asclepias suhulata near Diamond Valley on the 

 Dixie National Forest and asked for an investigation. A package 

 of the plant, which was said to have killed a gTeat number of cattle 

 on the Dixie Forest, was sent to the Bureau of Plant Industry for 

 investigation, but on account of the small quantity of material it 

 was impossible to determine whether the plant was poisonous. The 

 accounts of the losses of animals on the Dixie Forest, however, were 

 so definite that it was planned to make a more thorough field ex- 

 amination. Meantime, in 1910, Mr. Balthis, supervisor of the Alamo 

 National Forest, sent in specimens from Alamogordo, N. Mex,, 



1 In the Amer. Jour, of Vet. Med., Vol. XIV, pp. 1.35-136, Dr. L. H. Pammel, in ad- 

 dition to a review of the bulletin by Glover, Newsom, and Robbins, reports the treatment 

 used by a local veterinarian on sheep poisoned by whorled milkweed near Hotchkiss, 

 Colo. 



