5 BULLETIN 1274, U. S. DEPARTMENT OF AGRICULTURE 
The species used in the experimental work has been determined 
by W. TV. Eggleston, of the Bureau of Plant Industry, as Xanthium 
echinatum Murr. The material was collected at Salina, Utah, and 
on the shores of a large reservoir near Sterling, Utah. Considerable 
material was also used that was grown in sand beds at the Salina 
Experiment Station and in the Department of Agriculture green- 
house in Washington, D. C., from seeds collected at Salina. 
Plate I, .Figure 1, is a picture of a branch of the plant, showing 
the forms of the leaves and burs. Plate I, Figure 2, shows plants 
in the young cotyledon stage. It was in this stage and a little 
later, before the full development of the first pair of leaves, that 
the plants were found to be most poisonous. Plate II shows the 
shore of the reservoir, where much of the material was collected, 
and is typical of many places where the plant grows in abundance. 
The old burs accumulate on the shores of the reservoir, sometimes 
partly buried and sometimes bunched together on the surface. The 
young plants grow rapidly, forming dense masses around the shores. 
As the water of the reservoir is gradually lowered during the sum- 
mer, a band of young plants develops, this band varying in width 
in accordance with the moisture conditions. Thus for several weeks 
there is a succession of crops of the young plant. 
If the plants are toxic and the trouble is confined to the young- 
plants, as is shown later, it follows that under such conditions the 
dangerous season may be greatly prolonged. Where the plants 
grow on the shores of temporary ponds the growth may not cease 
until the ponds are entirely dried up. Each bur contains two seeds 
and it is a well-known fact that ordinarily only one seed germinates 
in the year following maturity, the other one germinating in the 
second year or later. So, while the plants are considered as annuals 
and theoretically can be exterminated if destroyed before the burs 
are formed, one must expect another crop from the seeds in which 
germination has been delayed. 
EXPERIMENTAL WORK 
The experiments on which this report is based were carried on 
in the years 1920, 1921, 1922, and 1923. Most of the work was 
done at the Salina Experiment Station, but a few experiments were 
made at the Bureau of Animal Industry Experiment Station. Beth- 
esda, Md., near Washington, D. C. There were, in all, 67 experi- 
ments with swine, 11 with sheep, 12 with cattle, and 19 with chickens. 
Table 1 contains a summarized statement of these experiments. 
TYPICAL CASE OF PIG 18 
Pig 18 was a female, 2 months old. of the Poland-China breed. 
She was in good, healthy condition at the time of the experiment and 
weighed 40.5 pounds. To this animal was given, at 9. IT) a. m., June 
'• ; . L.496 per cent of the animal's weight of Xanthium echinatum in 
I he young cotyledon stage. The plants were cut up and mixed 
with garbage and bran. At -! p. m. it was noticed a little of the 
plan! remained, but after the addition of more bran the animal 
ate i In- remainder. 
