The Bulletin 
19 
Comparison of White Snakeroot with Related Species 
Some of tlie species of Eupatorium are distinguished with difficulty 
from white snakeroot, which accounts for the fact that farmers on being 
shown white snakeroot and told that it is the cause of trembles, not in¬ 
frequently assert that their stock feed upon the plant without any ill 
effects. The casual observer cannot depend upon the color of the 
flowers to distinguish species, since more than thirty species of Eupa¬ 
torium have white flowers. Furthermore, Eupatorium incarnatum, 
which may have flowers tinged with pink or purple although frequently 
they are white, is practically indistinguishable from white snakeroot 
except by the presence of minute hairs on the corolla tube. These can 
be seen only with the aid of a hand lens. 
Twenty-nine species with opposite leaves have been described. Only 
seven of these, however, including white snakeroot, have manifestly 
stalked or petioled leaves. In this group five possess leaf blades which 
are similar in shape to those of white snakeroot. The leaf blades of 
the other one are fully twice as long as broad, which makes its separa¬ 
tion easily possible. 
Whether or not the roots are perennial is a distinguishing character, 
since only five species with perennial roots, in which group white snake¬ 
root is included, have been listed. Two of these are shrubby and the 
other three are herbaceous. In the latter group, the character of the 
leaf margin, whether it be provided with sharp or blunt teeth, is used 
in separating E. urticsefolium from E. aromaticum, and the absence of 
a beard on the corollas separates these two species from the other, 
E. incarnatum. 
The direction of attention to these points of similarity between white 
snakeroot and other species of Eupatorium will, it is hoped, serve to 
indicate that careful observation and experience are necessary in deter¬ 
mining whether one is dealing with white snakeroot or some of the 
other species which are not known to be poisonous, but which are com¬ 
monly present within the State. 
Names of the Disease 
This disease has been appropriately designated as trembles in ani¬ 
mals, because trembling is the most obvious symptom, and as milk- 
sickness in man, because it may be communicated to man through milk 
from cows affected with trembles. It has been given a number of 
other names, but it is not possible because of the mystery which has 
for so long surrounded the cause of the malady to determine whether, in 
every instance, reference is made to the same disorder. 
