Plants That Kill: White Snakeroot

Adapted from page 191 of Plants That Kill:

When Europeans started to settle in the Midwest region of the United States in the 1800s, they and their livestock began to fall ill. The animals developed violent trembling when they were forced to move or became agitated, and the disease became known as trembles. People who drank the milk of affected animals developed so-called milk sickness, and it is estimated that in some areas of Indiana and Ohio 25–50 per cent of the deaths of early settlers were caused by this condition. One casualty in 1818 was Nancy Hanks Lincoln, whose son, nine years old at the time, would become President Abraham Lincoln. 

Nowadays, human poisoning by white snakeroot (Ageratina altissima) is rare due to industrial milk production, but it is an historically interesting killer plant. Photo credit: Shutterstock, Wiert nieuman

It took some time to identify white snakeroot (Ageratina altissima, syn. Eupatorium rugosum) as the cause of trembles. Although the plant was initially suggested as the culprit in the 1830s, this was only confirmed in the early 1900s. This member of the daisy family (Asteraceae) grows in moist, shaded areas, such as along stream beds and near tree lines. Animals do not show any signs of being poisoned until they have been eating white snakeroot for one to three weeks, and symptoms finally progress to chronic degeneration of the skeletal muscles. Benzofuran ketones, including tremetone, are at least partly responsible for the toxicity of white snakeroot, and they are also found in another member of the daisy family, the rayless goldenrod (Isocoma pluriflora, syn. Haplopappus heterophyllus), which causes a similar disease in grazing animals. 

Plants That Kill: A Natural History of the World’s Most Poisonous Plants
By Elizabeth A. Dauncey & Sonny Larsson

This richly illustrated book provides an in-depth natural history of the most poisonous plants on earth, covering everything from the lethal effects of hemlock and deadly nightshade to the uses of such plants in medicine, ritual, and chemical warfare.

Featuring hundreds of color photos and diagrams throughout, Plants That Kill explains how certain plants evolved toxicity to deter herbivores and other threats and sheds light on their physiology and the biochemistry involved in the production of their toxins. It discusses the interactions of poisonous plants with other organisms–particularly humans—and explores the various ways plant toxins can target the normal functioning of bodily systems in mammals, from the effects of wolfsbane on the heart to toxins that cause a skin reaction when combined with the sun’s rays. This intriguing book also looks at plants that can harm you only if your exposure to them is prolonged, the ethnobotany of poisons throughout human history, and much more.

A must for experts and armchair botanists alike, Plants That Kill is the essential illustrated compendium to these deadly and intriguing plants.

  • Provides an authoritative natural history of the most poisonous plants on earth
  • Features hundreds of color illustrations throughout
  • Looks at how and why plants produce toxins
  • Describes the effects of numerous poisonous plants, from hemlock and deadly nightshade to poppies and tobacco
  • Explains poisonous plants’ evolution, survival strategies, physiology, and biochemistry
  • Discusses the uses of poisonous plants in medicine, rituals, warfare, and more


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