B. P. I.— 3->9. 



MISCELLANEOUS PAPERS. 



H. I'. I.— '288. 



TUL LARKSl'URS AS POISONOUS PLAXTS." 



By Albert C. Crawford, Phftrmncologlsl, roixoa&iu<-PluiU Invesligntions. 



INTRODUCTION. 



Tliroughout the United States many species of larkspur (Doli)hin- 

 luni) occur. Some of these form an important feature of the western 

 hindscape; '' others, such as Delphinium ajacis, on account of their 

 beauty have been cultivated in <;ardens, from whence they. have 

 escaped and become a jiest to the farmer.'" 



The <j;enus Delphinium is in a very confused condition botanically 

 and needs revision.'' However, the l)otanical characteristics of iUv 

 irenus are clearlv marked anil constitute sufficient reason for consider- 

 ing any plant bearing them as deserving of suspicion. Dciphinitrni 

 troUiifoVnnn, (iray, represented in the accompanying illustration 

 (Plate I), shows these characteristics. In Canada ' and in our West- 

 ern States, especially in Colorado and Montana, various species of 

 I)eli)hiniuni have been accused of stock poisoning, although feeding 

 experiments with these plants have varied in their results, and opinion 

 in the West has been by no means uniform as to their poisonous prop- 

 erties. According to Wilcox,^ in ]Montana GOO sheep were poisoned by 

 Delphiniwm menziesii on one ranch, of which 250 died. In India the 



1 Of the many kinds of plants of the western ranges poisonous to stork, vari- 

 ous species of larkspur are among the most destructive, especially in the moun- 

 tainous regions of Colorado, Wyoming, and Montana. 



About two years ago a study of the poisonous properties of one of the most 

 common species was undertaken cooperatively by the Colorado Agricultural 

 Experiment Station and the Office of Poisonous-Plant Investigations, the field 

 collections .ind field tests being carried on by Dr. George H. Glover, veterinarian 

 of the station, and the technical laboratory studies l>y Dr. A. C. Crawford. 

 Pharmacologist, mider the direction of Dr. R. H. True, Physiologist in Charge 

 of the Poisonous-Plant Investigations of the Bureau of Plant Industry. The 

 principal results of Doctor Crawford's work are here summarized. 



It is shown that this larkspur is most virulent in its early stages and becomes 

 much less active toward flowering time. The importance of the functions of 

 elimination in bringing about recovery is also clearly indicated, and the signifi- 

 cance of this fact in harmonizing the varying results of different investigations 

 is pointed out. — B. T. Galloway, Chief of Bureau. 



^ Meehau, T. Delphinium Bicolor. Meehan's Monthly, vol. 12, p. 1. 1902. 



c Rept. Comr. Agr. for 1865, p. 510. 



^ Huth, E. Monographic d. Gattung Delphinium. Bot. Jahrb., vol. 20, p. 322. 

 1895. 



'^ Noxious Weeds and How to Destroy Them. Government of Northwest Ter- 

 ritory, Dept. Agr. Bui. 2, p. 27. 1900. 



f Chesnut, V. K. Preliminary Catalogue of Plants Poisonous to Stock. Ann. 

 Rept. Bur. Animal Ind., 1S!>8, p. 400. 



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