Eupatorium rugosum Houtt.—White snakeroot, snakeroot
FAMILY: Compositae (Asteraceae)—the Daisy Family (see Arctium)
PHENOLOGY: Snakeroot flowers from July through October.
DISTRIBUTION: Eupatorium rugosum grows in eastern North America. Abundant in Pennsylvania, it is found in moist areas, rich open woods, and along streams. It often forms dense colonies in areas where logging has cleared regions of the forest.
PLANT CHARACTERISTICS: The heads of white flowers are small and contain only disk flowers: 3 to 4 mm long; heads: contain 10 to 30 flowers; leaves: thin, opposite, evidently petioled, sharply serrate, acuminate, the larger ones 6 (to 18) x 3 (to 12) cm long; stems: 1.5 dm, from a shallow mat of fibrous, perennating roots.
POISONOUS PARTS: The poisonous parts are the leaves and stems; toxicity decreases with drying. Seasonal or ecological variation may affect toxic principles; frost does not reduce toxicity.
SYMPTOMS: The following conditions are recorded in toxicosis: trembling, especially of the flank and hind legs; slow, lethargic or sluggish behavior ("the slows"); stiffness in movement or ataxia; coma; and death. Horses seem less prone to trembling. Livestock may exhibit constipation, nausea, vomiting, slobbering, loss of appetite, or labored or rapid breathing. An acetone odor on the breath may result from ketosis in severely poisoned animals. Postmortem: gross and histological lesions: fatty degenerative changes in liver and kidney; heart and gastrointestinal hemorrhages.
POISONOUS PRINCIPLES: Poisoning is possible due to an unstable, fat-soluble alcohol called tremetol, which has a phenyl nucleus and an incompletely characterized resin acid. Tremetol is an aromatic, straw-colored oily liquid. The principal ketone, tremetone, is also suspected to be toxic.
CONFUSED TAXA: There are more than twenty species of Eupatorium in the eastern U.S., with most encountered in Pennsylvania. Because E. rugosum may be difficult to identify accurately, any suspected material should be examined by a specialist.
SPECIES OF ANIMALS AFFECTED: Species known to be susceptible are fowl, sheep, horses, cattle, hogs, and humans; illness may be experimentally induced in various laboratory animals.
TREATMENT: (26); treat for anuria, liver, and kidney damage.
OF INTEREST: "Trembles" and "the slows" are not the only illness produced from Eupatorium toxicosis. "Milksickness" was a common disease in the Colonial period, reaching its peak in the first half of the 1800's. Since tremetol is readily excreted in milk, poisoning can occur from ingestion of milk from lactating animals that have eaten Eupatorium. During the early pioneer period, entire villages were abandoned and human population centers were reduced to less than one-half the original number due to milksickness because the etiology of the disease remained a mystery. The amount of plant consumed to elicit sickness varies from 1-20% of the animal's weight and depends on many factors. Because the toxin is cumulative, the onset of symptoms varies from less than 2 days to as much as 3 weeks. Death follows from 1 day to 3 weeks after the symptoms appear. Recovery is good if the disease can be countered before ketosis appears. In many cases, prognosis is poor and recovery is rare, slow, and incomplete. Milksickness in humans begins as a few days of weakness, loss of appetite, abdominal pain, and violent vomiting followed by obstinate constipation, severe thirst, loss of ingested fluids by vomiting, tremors, acetone breath, prostration, delirium, coma, and death. The disease can be fever-producing or the temperature may be subnormal. Mortality ranges from 10-25%, but the massive loss of human life seen in centuries past does not occur owing to current practices of animal husbandry and the pooling of milk from many producers.