U. V. I.— 288. 



THE LARKSPURS AS POISOXOUS PLANTS.' 



INTRODUCTION. 



Throughout the United States many species of hirkspur (Delphin- 

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

 landscape;'' others, such as Ifclphinium ajar'ts, on account of their 

 beauty have been cuhivated in gardens, from whence they have 

 escaped and become a pest to the farmer.'' 



The genus Delphinium is in a very confused condition botanicj'.lly 

 and needs revision.'' However, the botanical characteristics of the 

 genus are clearl}' marked and constitute sufficient reason for consider- 

 ing any plant bearing them as deserving of suspicion. Dclphinhnii 

 ti'oUiifolium Gray, 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 

 Delphinium have l)een accused of stock poisoning, although feeding 

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

 in the West has been b}^ no means uniform as to their poisonous prop- 

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

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



a Of the man.v kinds of plants of the western ranges poisonous to stocli, vari- 

 ous species of hirkspur are among tlio most destructive, especially iu 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 and field tests l»eing carried on hy Dr. George II. Glover, veterinarian 

 of the station, and the technical laboratory studies by Dr. A. C. Crawford, 

 Pharmacologist 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. — Rodney II. True, Phi/siolof/i.st in Charye of Poisonous-Plant 

 Investigations. 



&Meehan, T. Delphinium Bicolor. Meehan's Monthly, vol. 32. p. 1. 1902. 



c Rept. Comr. Agr. for 18G5. p. 510. 



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

 1895. 



e 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., 1898, p. 400. 

 lll-i 



