STOCK-POISONING PLANTS OF THE RANGE. 17 
White Loco (Oxytkopis lambeeti). 
Of all the loco plants the most destructive is the " white loco," or 
" rattleweed," Oxytropis lamberti of the botanists. This is not be- 
cause of its greater toxicity, but because it grows in great abundance 
over a wide extent of territory and is poisonous not only to cattle, 
goats, and sheep but to horses. It is found in the Plains region east 
of the Rocky Mountains from Alaska to Mexico. Like all the loco 
plants, it belongs to the Leguminosse or pea family, the family in 
which are found peas, beans, clovers, alfalfas, etc. It is a stemless 
perennial plant, living two or three years or more, and has a long 
root system which enables it to withstand conditions of drought. 
The leaflets of the compound leaves are slender, more or less hairy, 
and of an olive-green color. Thrifty plants are a foot or more in 
height. 
The spikes cf flowers are borne on stems extending above the 
leaves and are commonly of a prevailing white color, hence its name 
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 graduations 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 
" rattleweed." 
Plate XV is a picture of the white loco as found in the plains of 
Colorado. Plate XVI 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 
Joco. 
Astragalus drtjmmondi. 
In Plate XIX is given a picture of Astragalus drummondi, 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. 
Oxytkopis besseyi. 
Plate XVII shows a picture of Oxytropis besseyi. This is a legu- 
minous plant, rather common in the Yellowstone Valley, which is very 
clcsely 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 
