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UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1274 
Washington, D. f . 
September 18, 1924 
COCKLEBURS (SPECIES OF XANTHIUM) AS 
By C. Dwight Maksh, Physiologist in Charge of 
oning by Plants; Glenwood C. Roe, Assistant, 
gist, Pathological Division, Bureau of Animal 
CONTENTS 
Page 
Purpose and scope 1 
Historical summary __ 2 
The cocklebur plant 5 
Experimental work 6 
Typical case of pig 18 . 6 
Discussion and general conclusions- 7 
Symptoms in pigs 7 
Symptoms in sheep and cattle 12 
Symptoms in chickens 12 
Autopsy findings 12 
Microscopic changes in tissues- 13 
Toxic and lethal dosage 15 
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Page 
Discussion, etc. — Continued. 
Time from feeding to appearance 
of symptoms 16 
Duration of sickness 16 
Effect of continued feeding — 17 
Animals poisoned by cocklebur- 18 
Part of plant poisonous 18 
Mechanical injury by burs 19 
Toxicity of dried plant 20 
Remedies 21 
Summary 22 
Bibliography 22 
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PURPOSE AND SCOPE 
For several years requests have come to the United States Depart- 
ment of Agriculture for information in regard to the poisonous prop- 
erties of the cocklebur, a well-known weed. Frequently these requests 
have been accompanied with more or less detailed statements in re- 
gard to supposed cases of the poisoning of livestock by these weeds. 
Some correspondents have complained of heavy losses, especially of 
pigs. Published statements, however, in regard to the plants have 
been somewhat contradictory, and it has seemed strange that if they 
were really poisonous there were not much greater losses, for cockle- 
burs are widely distributed in the United States and grow with great 
luxuriance. The plants are found in nearly all parts of the world 
and have become especially noxious in South Africa and Australia, 
where, after being introduced, they have made themselves very 
much at home. 
From the stock raiser's standpoint the question of the poisonous 
properties of the plant has become very important. On this account 
an experimental study of cockleburs has been made by the Depart- 
ment of Agriculture. The results of this work have brought out the 
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