White Snakeroot

White Snakeroot (Ageratina altissima, syn. Eupatorium rugosum), also known as White Sanicle, is a poisonous perennial herb in the family Asteraceae, native to eastern North America.

Plants are upright or sometimes ascending and can grow up to 1.5 meters tall, they are found in woods and brush thickets, and bloom mid to late summer or fall. The flowers are a clean white color and after blooming small seeds with fluffy tails are released to blow in the wind. Plants can be weedy in shady landscapes and in hedgerows, since they are adaptive to different growing conditions and grow were there is open ground in shady locations, producing clumps with a number of stems. There are two different varieties that differ in the length of the flower phyllaries and shape of the apices.

Toxicity
White Snakeroot contains the toxin tremetol and when consumed by cattle the meat and milk becomes contaminated. When milk or meat from cattle feeding on White Snakeroot is consumed by humans, the poison is passed onto humans and can result in tremetol poisoning called milk sickness (notably the cause of death of Nancy Hanks, mother of Abraham Lincoln). It is also poisonous to horses, goats, and sheep. Signs of poisoning in these animals include depression and lethargy, hind feet placed close together (horses, goats, cattle) or held far apart (sheep), nasal discharge, excessive salivation, arched body posture, and rapid or difficult breathing.