4 
Bulletin 113. 
bulletins from various State experiment stations, notably North 
Dakota, Idaho, Montana, have followed, and not only been of great 
practical benefit to the stockmen in identifying the most danger¬ 
ous of these plants, but seems to have aroused the spirit of inquiry 
on the part of scientists for more extended research regarding them. 
This bulletin is issued with the view of placing before the farm¬ 
ers and stockmen of the State a plain and concise statement, with 
illustrations, regarding larkspur and a few of our most common 
and most to be dreaded range plants. 
Early in the spring of 1905 the Colorado Experiment Station 
undertook a co-operative experimental investigation of loco and 
larkspur with the Department of Agriculture. The work with 
loco weeds has been carried on throughout the summer and fall, 
with headquarters at Hugo, Colo., under the direct supervision of C. 
Dwight Marsh, of the U. S. Department of Agriculture, and the 
report will follow in due time. 
Poison weeds in general throughout the State, with special 
reference to larkspur, has been the subject of special inquiry 
by the Experiment Station, at Fort Collins, and in this investigation 
has been ably assisted by the Bureau of Plant Industry, at Wash¬ 
ington, by way of identification of plant, chemical analysis, deter¬ 
mination of lethal dose, etc. 
Out of the large number of plants known to be poisonous under 
certain conditions the two loco weeds known as white and purple 
loco, and several species of larkspur, have been singled out for 
special investigation at this time as they are held responsible for 
at least ninety per cent, of the loss in this State. While scattering 
reports come in from various sections of the State of loss which 
can be attributed unly to camas, lupin, hemlock, and various others, 
in the great majority of cases it is from the loco weeds in the east¬ 
ern half of the State and larkspur in the mountainous regions. 
Nearly every community of the State has been visited within the 
last year, and a fair knowledge of the most prevalent poisonous 
weeds obtained. In visiting various sections of the State, and by 
correspondence as well, I find that unless the plant under discus¬ 
sion is at hand there is no certainty that we both have the same 
plant in mind. There is no general agreement among stockmen 
themselves either as to the common names, identity, or symptoms 
from poisoning of even our most common poison weeds. White 
loco weed and rattle weed are spoken of as different plants; lark¬ 
spur is commonly called aconite; death camas as wild onions, etc. 
I have corresponded with different parties with reference to the 
loss sustained from larkspur, and upon receiving the specimens 
found them to be something entirely different. This, however, 
simply causes some inconvenience. It does not present a serious 
