14 BULLETIN 942, U. S. DEPARTMENT OF AGRICULTURE. 



similar relation in this plant. It follows that the losses by the 

 whorled milkweeds are for the most part caused by eating the leaves 

 rather than the stems. 



SUMMARY. 



Closely allied to the extremely poisonous whorled milkweed Ascle- 

 pias galioides are two species, A. j?umila, growing in the plains 

 region east of the Rocky Mountains, and A. verticillata var. geyeri, 

 growing in the eastern United States. 



These two species produce in animals symptoms and pathological 

 results closely resembling those produced by A. galioides. 



As compared with A. galioides, A. pumila is about one-third as 

 toxic and the Missouri Valley species (A. verticillata var. geyeri) 

 about one-tenth as toxic. 



As stock-poisoning plants these last two species have no history, 

 but there is reason to think that if grazing animals were closely con- 

 fined to them injurious results would follow. 



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