84 BULLETIN 365^ U. S. DEPARTMENT OF AGEICULTTJEE. 



in Farmers' Bulletin No. T20, Prevention of Losses of Live Stock 

 from Plant Poisoning. 



After the plant has matured, as has been shown elsewhere, its 

 toxicity diminishes, and cattle, finding at the same time an abun- 

 dance of other more attractive feed, eat very much less of the larkspur 

 so that the danger of poisoning is very slight, and in the fall, after 

 the plant begins to dry, cattle may and do eat it in large quantities 

 with impunity. 



It is generally considered by stockmen that poisoning is more 

 likely to occur immediately after a rain, or even when the plants are 

 wet with dew. There seems to be no reasonable explanation of the 

 supposed fact of the greater toxicity of the plant when wet. It 

 seems possible, however, when cattle are feeding hastily in a larkspur 

 area after a rain, that rather than thrust their heads and faces into 

 the wet grass they may eat more of the higher plants; in this way 

 they would consume more of the larkspur and consequently become 

 poisoned. Cattle, too, in the time of a storm gather together in the 

 valleys and under trees where larkspur is very abundant, and doubt- 

 less eat more of it on this account. . 



Probably, also, when cattle are handled upon a supposed poisonous 

 area it would aid somewhat in preventing loss if pains were taken 

 to make sure that none of them were constipated. This probably 

 could be accomplished, where cattle are watered at specific places, 

 by the use of a small amount of magnesium sulphate or sodium 

 sulphate in the drinking water. 



GENERAL SUMMARY. 



1. The larkspurs from very ancient times have been recognized as 

 poisonous plants, but complaints of stock poisoning by these plants 

 have been confined almost entirely to the mountain ranges of western 

 North America, where heavy losses have been reported, especially 

 among cattle. 



2. It is rarely possible to recognize macroscopically larkspur ma- 

 terial in the stomach contents of cattle. By means of microscopic 

 sections of stems, however, not only can Delphinium be distinguished 

 from other plants but groups of the genus can be distinguished from 

 each other. The genus falls into six different types of stem struc- 

 ture. 



3. Experimental feeding of larkspur was carried on for three 

 seasons at Mount Carbon, in Gunnison County, Colo. In this work 

 four species of Delphinium were used which have been identified as 

 Delphinium harheyi^ D. mensiesii, D. andersonii, and D. robusturri. 

 A large number of animals were used in this work, including horses, 

 cattle, and sheep. Similar feeding experiments were conducted 



