ORDEAL POISONS - Wicked Plants: The Weed That Killed Lincoln's Mother and Other Botanical Atrocities - Amy Stewart

Wicked Plants: The Weed That Killed Lincoln's Mother and Other Botanical Atrocities - Amy Stewart (2009)


Among nineteenth-century European explorers a story circulated about the existence of a West African bean that could determine a person’s guilt or innocence. According to local custom, the accused would swallow the bean, and what happened next would determine the outcome of the trial. If he vomited the bean, he was innocent, and if he died, he was guilty and got what he deserved. A third alternative existed: he could purge the nut, or evacuate it through his bowels, in which case he was also determined guilty and sold into slavery as punishment. (A thriving slave trade dating back to the early 1500s facilitated this quirk in the West African criminal justice system.)


This practice was known as trial by ordeal, and plants used for the trials were called ordeal beans. Several plants were used; judges could choose a less toxic plant when they wanted to influence the outcome in favor of the accused.


Physostigma venenosum

The ordeal poison of choice, the Calabar bean flourishes in warm, tropical climates; reaches up to fifty feet in height; and produces lovely red blossoms like those of the scarlet runner bean, followed by long, fat seed-pods and hefty dark brown beans.

The alkaloid physostigmine is responsible for the bean’s toxic effects. It works like nerve gas, disrupting the lines of communication between nerves and muscles. The result is copious saliva, seizures, and loss of control over bladder and bowels; eventually, as it becomes impossible to control the respiratory system, death by asphyxiation will occur.

Its chemical composition, along with a little armchair psychology, may explain why the plant had such different effects on the poor souls facing a trial by ordeal. A person who knew they were innocent might chew the bean quickly and swallow it with pride, ingesting a quick dose that would cause them to vomit before the bean could do more damage. A guilty party, dreading death, might take tiny, slow bites. Ironically, this attempt to prolong their own life would only hasten their death by delivering a gradual, well-digested dose of poison.

By the 1860s Calabar beans were the talk of London. Dr. James Livingstone returned from Africa with an account of a poison he called muave and noted that tribal chiefs would volunteer to drink the muave to prove their innocence, their strength of character, or to demonstrate that they had not been the victim of witchcraft. Mary Kingsley, a pioneering explorer who broke many taboos by traveling alone to previously unexplored parts of Africa, wrote in 1897 about an oath some tribal members would make before taking an ordeal poison they called Mbiam: “If I have been guilty of this crime … Then, Mbiam! THOU deal with me!”

These frightening chants did not stop intrepid British scientists from testing the beans on themselves. In an 1866 London Times story titled “Scientific Martyrdom,” Sir Robert Christison is described as having come “very near killing himself in testing the effect of the recently introduced Calabar bean upon his own organism … and was as nearly face to face with death as a man well can be and yet escape its jaws.”


Cerbera tanghin

Employed in Madagascar, this relative to the suicide tree Cerbera odol-lam is poisonous in all parts; even smoke from the burning wood can be toxic. However, the nuts deliver the poison in the most convenient form for trial by ordeal.


Erythrophleum guineense or E. judiciale

Observed in use along the banks of the Congo, the curvy, reddish-brown bark of this tree is toxic enough to stop the heart. Ranchers know to keep their cattle away from it, because it could even kill a steer. Other names for the tree include “ordeal bark” and “doom bark.”


Strychnos nux-vomica

The seed of the strychnine tree is a potent enough poison to make it useful as an ordeal bean. Any prisoner offered nux vomica seeds to prove their innocence would be well advised to do some fast talking and suggest another ordeal poison, because the strychnine is far more likely to cause convulsions and death by asphyxiation than vomiting.


Antiaris toxicaria

This Indonesian tree produces a toxic sap that’s also useful as an arrow poison. It was once (falsely) believed to produce narcotic fumes, and tales circulated that prisoners were being put to death simply by tying them to the upas tree and letting its sap and fumes slowly poison the condemned.





In 1895 Sigmund Freud wrote to a colleague that “a cocainization of the left nostril had helped me to an amazing extent.” A modest, medium-sized shrub had transformed Freud’s entire outlook on life. “In the last few days I have felt quite unbelievably well,” he wrote, “as though everything had been erased … I have felt wonderful, as though there never had been anything wrong at all.”


Tropical rain forest

South American


Archaeological evidence shows that coca leaves were placed between the cheek and gum as a mild stimulant as early as 3000 BC. When the Incas came into power in Peru, the ruling class seized control of the coca supply, and when Spanish conquistadores arrived in the sixteenth century, the Catholic Church banned the use of the devilish plant. Eventually, practical considerations won out, and the Spanish government realized that it would be better off regulating and taxing the use of coca, while making it available to slaves who had been forced to work in gold and silver mines. The Spaniards found that, with enough coca, the natives could work quickly, for long hours, with very little food. (Never mind the fact that most died after a few months of this treatment.)

An Italian doctor named Paolo Mantegazza promoted the medicinal and recreational use of the leaves of the coca plant in the mid-nineteenth century. He was so enthralled by his discovery that he wrote: “I sneered at the poor mortals condemned to live in this valley of tears while I, carried on the wings of two leaves of coca, went flying through the spaces of 77,438 words, each more splendid than the one before …”

Cocaine, an alkaloid that can be extracted from coca leaves, has been used as an anesthetic, a pain reliever, a digestive aid, and an all-around health tonic. Trace amounts were present in early versions of the soft drink Coca-Cola; while the company’s recipe is a closely guarded secret, coca extract is still believed to be a flavoring, just without the cocaine alkaloid. The leaves are legally imported by an American manufacturer, which buys it from Peru’s National Coca Company, transforms it into Coca-Cola’s secret flavoring, and extracts the cocaine for pharmaceutical use as a topical anesthetic.

The coca plant’s ability to inspire humans to go to war, both against each other and against the plant, may be its most deadly quality.

The coca plant’s ability to inspire humans to go to war, both against each other and against the plant, may be its most deadly quality. A healthy shrub can produce three crops a year of fresh, glossy leaves. The cocaine and other alkaloids in the leaves serve as a natural pesticide, helping to ensure that the plant flourishes even when it’s under attack. Although a few different species can be used to extract cocaine, the plant used most often for this purpose is Erythroxylum coca, which grows along the eastern slope of the Andes mountain range.

In native Andean communities, coca leaves are still chewed as a mild stimulant. Some pharmacological studies suggest that this provides a much milder and nonaddicting stimulation that works on a different part of the brain than cocaine does. The leaves are surprisingly nutritious and very high in calcium, prompting a minister in Bolivia’s new pro-coca government to suggest that instead of milk, coca leaves should be fed to schoolchildren.

The shrub has also survived attacks from another kind of enemy: the drug war’s aerial spraying of the herbicide glyphosate. Drug eradication programs have been foiled by a new, resistant variety of coca called Boliviana negra. It emerged, apparently, without any help from scientists in laboratories. Instead, naturally resistant plants have simply been discovered in the fields and passed from farmer to farmer.

Advocates of traditional coca farming point out that coca is an Andean crop dating back several thousand years, while cocaine was invented in Europe 150 years ago. The problems created by cocaine use, they suggest, should be solved within those countries and not at the expense of the coca plant.

Meet the Relatives Erythroxylum coca is the best-known member of this family of angiosperms, but E. novagranatense also contains the cocaine alkaloid. E. rufum, or false cocaine, can be found in some botanical gardens in the United States.





Coyotillo is a modest shrub of the Texas plains, rarely reaching more than five or six feet in height. The bright green, untoothed leaves and pale green flowers make it an entirely forgettable shrub. But the round black berries it produces in fall would be impossible to forget.


Dry southwestern desert

American West

Tullidora, cimmaron, palo negrito, capulincillo

Coyotillo berries contain a compound that causes paralysis—but not immediately. The unlucky subject may not realize that he or she has been poisoned for several days or even weeks. But then, the paralysis sets in—and if this were a murder mystery, it would happen just as the unlucky victim was driving through a dark mountain pass or trying to sneak past the jewelry store’s security alarm. What author could invent a more devious drug?

Animals have been known to lose control over their hind legs, or to lurch backward for no reason they could understand, under the influence of this harmless-looking berry. In the laboratory, administering just the right dose to animals would cause quadriplegia. Livestock browsing freely on the shrub could eventually lose control of their limbs entirely, and death would not be far behind.

Coyotillo goes to work on the feet first and then moves to the lower legs. Once the limbs are still, it brings the respiratory system to a halt, and then it silences the tongue and throat. The plant thrives along the border between Texas and Mexico. Ironically, the name coyotillo is the diminutive of the Spanish word coyote, given to a person who helps illegal immigrants make the dangerous border crossing into the United States. One study counted about fifty people in Mexico who died from eating the berries during a two-year period.

Once the limbs are still, coyotillo brings the respiratory system to a halt, and then it silences the tongue and throat.

Coyotillo thrives in the canyons and dry riverbeds of southern Texas, New Mexico, and northern Mexico, where it can tolerate the mean heat and scorched earth. Give it the right conditions and it may reach twenty feet, the size of a small tree.

Meet the Relatives Coyotillo is a member of the buckthorn family; many shrubs in this family play host to butterflies. Most produce berries, but they don’t pose the same threat.