white snakeroot, Eupatonum rugosum, tremetol, tremetone
White snakeroot is a perennial composite whose foliage is poisonous to livestock. The poison is an unidentified substance contained in a mixture called tremetol. Most cases of poisoning occurred in late summer, and it was presumed livestock were forced to eat the plants because of a dearth of forage. Field observations indicate cattle will voluntarily eat white snakeroot and perhaps the plant varies seasonally in toxicity. Preliminary bioassy using minnows (Notropis spp.) exposed to extracts of plants gathered monthly in 1977 indicated the plants were most toxic in July and August. Tremetol was extracted from plants gathered monthly in 1978. The highest concentrations were from plants gathered in August and September.
Proceedings of the Iowa Academy of Science
©1982 Iowa Academy of Science, Inc.
Kaufmann, Gerald W.
"Seasonal Variation of Tremetol Concentrations Found in White Snakeroot, Eupatorium rugosum Houtt (Compositae),"
Proceedings of the Iowa Academy of Science, 89(4), 151-152.
Available at: https://scholarworks.uni.edu/pias/vol89/iss4/4