14 BULLETIN 365, U. S. DEPARTMENT OF AGRICULTURE. 
recognized as different plants. The flowers of larkspur and aconite 
are so different, however, that few fail to recognize the difference 
after flowering. 
SPECIES OF DELPHINIUM CONCERNED IN LARKSPUR POISONING. 
The classification of the species of Delphinium is in a somewhat 
unsatisfactory condition, and until a thorough revision of this genus 
has been made it is hardly possible to speak authoritatively in re- 
gard to the distribution of the various species. Generally speaking, 
we find two great groups, the tall and the low larkspurs. The tall 
larkspurs embrace the species that are more or less closely related to 
the old species Delphinium scopulorum Gray. The form that has 
been used in the experimental work in Colorado is known provi- 
sionally as Delphinium barbeyi Huth, and grows at an elevation of 
8,000 feet and higher. Delphinium robustum Rydb., with which a 
single feeding experiment was carried on, is also a tall larkspur. 
The tall larkspur used in the feeding experiment at the Greycliff 
station was Delphinium cucullatum A. Nels., which is common in 
the mountains of Montana. The species of low larkspur used at 
the Mount Carbon station was Delphinium menziesii D. C, of which 
the name Delphinium nelsonii Greene, is a synonym, while that fed 
in Montana was Delphinium bicolor Nutt. The tall larkspurs grow 
throughout the season, maturing in the late summer while the low 
larkspurs mature and die early in July. Although experimental 
work has not been carried on by the authors in any other States than 
Colorado and Montana, there is every reason to think that the plants 
found in other localities have the same properties and produce the 
same effects as the larkspurs of Colorado. 
From the fact that the low larkspur dies early in July, cases of 
poisoning from this plant occur mainly in the month of June, and it 
is commonly thought by the stockmen that the plant ceases to be 
poisonous when it blossoms; but as shown elsewhere in this report, 
it is probable that it is poisonous during its whole life. The fact 
that fewer cases of poisoning occur when the plant is in flower is 
probably because at that time nutrient grasses are more abundant 
and the animals eat less of the larkspur. The tall larkspurs are also 
poisonous early in the season and these poisonous properties, as 
shown elsewhere, may continue until the maturity of the plant. 
The cases of poisoning which occur in other States are due to species 
which correspond in general with the tall and low larkspurs of 
Colorado. 
Delphinium barbeyi Huth. 
Delphinium barbeyi (PI. I) is a perennial, growing from buds at 
the apex of a long woody root. The stems are pubescent and more 
