6o 



PASTORAL AND AGRICULTURAL BOTANY 



Larkspurs (Delphinium Ajacis, D. bicolor, D. camporum, D. Geyeri, 

 G. glaucum (Fig. 22), D. Menziesii, D. Nelsoni, D. scopulorum, D. tricorne 

 D. trolliifolium) are responsible for cases of poisoning. The principle 

 usually increases its virulence with age. ' Pammel in his "Manual of 

 Poisonous Plants" gives a circumstantial account of each of the principal 

 species of larkspurs, and the feeding experiments which have been tried 

 with each plant. With the exception of the European, Delphinium Ajacis, 



FIG. 22. Tall mountain larkspur (Delphinium glaucum). One-half natural size- 

 (After Hall, Harvey M., and Gales, Harry S., Stock Poisoning Plants of California. Bull- 

 249, University of California Agricultural Experiment Station, 1915. P- 232.) 



all the other species mentioned above are western American (Fig. 23), a 

 few extending into the eastern United States. As the cattle ranges of 

 western America, as in California, include habitats such as moist meadows, 

 gulches, borders of springs, or ponds, open hillsides, sparsely forested 

 areas and the open steppes, we find the species varying with the habitat 

 conditions, and with this we find that next to the loco weed, the larkspurs 

 are the most harmful and poisonous of the plants found on the open 

 ranges (Fig. 24). 



