STOCK-POISONING PLANTS OP THE RANGE. 5 



of white loco. The corolla, however, is frequently streaked with 

 purple; sometimes the calyx is red; and sometimes, particularly in 

 mountain regions, the whole corolla may be of a deep violet or purple 

 color. All gradations in color may be found between these extremes. 

 When the plants are in fruit the pods rattle as one hits them in walk- 

 ing, very closely imitating the rattle of a rattlesnake, hence the name 

 "rattle-weed." 



Plate I is a picture of the white loco as found in the plains of Colo- 

 rado. Plate II shows a field of the plant in blossom. The latter 

 picture was taken in the Yellowstone Valley of Montana, but it 

 could easily be duplicated in Wyoming or Colorado. 



It is evident that where the plant occurs in these great numbers 

 such a thing as eradication is impossible except by plowing over the 

 whole country. If animals are turned loose in such a region as this 

 they certainly will have an opportunity to obtain an abundance of 

 loco. 



ASTRAGALUS DRUMMONDI. 



In Plate III is given a picture of Astragalus drwnmondi, which 

 occurs in many regions in. connection with the white loco and is fre- 

 quently considered a loco plant. The plant is readily recognized by 

 its coarse stems and yellowish flowers, both the flowers and pods 

 being somewhat dependent. Many people consider this a dangerous 

 plant, but extensive experiments by the Department of Agriculture 

 have shown that it is entirely harmless and need not be feared. The 

 picture is given here only that stockmen may be able to recognize it 

 as a plant which need not be avoided. 



OXYTROPIS BESSEYI. 



Plate IV shows a picture of Oxytropis besseyi. This is a leguminous 

 plant, rather common in the Yellowstone Valley, which is very 

 closely allied to the white loco and is frequently mistaken for it. 

 The flowers are of a deep-pink color, and the plant, while it grows in 

 the same regions as the white loco, is found upon the arid barren 

 summits of hills, the white loco growing most abundantly at slightly 

 lower levels. The two plants intermingle to some extent, but after a 

 little experience one is able to distinguish between them, as there 

 are certain noticeable differences in the leaves. Oxytropis besseyi is 

 known in Montana sometimes as the red loco, because of the color 

 of the flowers. Although the plant is closely related to the white 

 loco and grows in the same regions, there is abundant experimental 

 evidence that it is harmless. It should not be considered as a loco 

 plant. The writer considers that the term "loco" should be applied 

 only to such leguminous plants as have been proved to have poison- 

 ous properties. 



