DON’T LOOK NOW - 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)


Many plants that raise a rash on the skin or produce tiny, irritating thorns can also cause vision problems, including blindness. Here are a few of the most egregious examples:



Toxicodendron vernix

Most people in the eastern United States know to avoid poison sumac, a close relative of poison ivy and poison oak. But one young man had to learn his lesson the hard way. In 1836, at the age of fourteen, Frederick Law Olmsted wandered into a patch of poison sumac and got covered in the sap. Soon his face was horribly swollen and he couldn’t open his eyes at all.

It took him weeks to make a partial recovery, but the damage to his eyesight persisted. He couldn’t return to school for over a year, and he once wrote that the problems with his eyes lasted much later into his life. It may be that this time off was just what the boy needed to nurture his interest in the outdoors and that it led to his career as a visionary landscape designer. He wrote, “While my mates were fitting for college I was allowed to indulge my strong natural propensity for roaming afield and day-dreaming under a tree.” Perhaps that year of daydreaming provided the initial inspiration for New York’s Central Park, which he designed twenty years later.


Descurainia pinnata

This inconspicuous annual grows to two or three feet tall and produces small yellow blooms in the spring. It flourishes in dry fields and deserts throughout the United States. Its bitter taste discourages people from eating it, but cattle will graze on it, and the consequences can be deadly. Their tongues become paralyzed. They begin “head pressing,” butting their heads up against some hard object like a fence. Finally, the tansy mustard makes them go blind. Given the head pressing, the tongue paralysis, and the blindness, it is impossible for them to eat or drink, and they die of starvation and dehydration.


Excoecaria agallocha

This Australian mangrove tree—another member of the highly irritating Euphorbiaceae family—has earned the common name “blind-your-eye” for the temporary blindness, burning, and itching that its milky sap can cause. If the plants are burned, the smoke will also seriously irritate the eyes.


Mucuna pruriens

In 1985 a New Jersey couple called an ambulance after developing a severe rash. They blamed it on some mysterious fuzzy bean pods they found in their bed. The paramedics developed the same symptoms, and everyone had to be treated at the emergency room. A nurse at the hospital even started itching after touching one of the patients. The apartment had to be completely decontaminated, including cleaning of all carpets and fabrics. The pods were identified as cowhage.

Cowhage is a climbing tropical vine in the bean and pea family. It produces four-inch-long, light brown, fuzzy pods that are covered with as many as five thousand stinging hairs. Even specimens that have been preserved in museums for decades can cause severe itching. If any of the tiny barbs get in the eyes, they can cause short-term blindness.


Rhodomyrtus macrocarpa

This small Australian tree, also called a native loquat, has long been rumored to cause permanent blindness to people who eat the small red fruits. There were several newspaper accounts of children going blind in the early 1900s, and in 1945 a newspaper reported that twenty-seven soldiers from New Guinea went blind after sampling the fruit. One possible cause is a fungus called Gloesporium periculosumthat infects the tree. Australians know better than to take their chances.


Brugmansia spp.

A relative of datura, this South American plant can bring on an alarming case of “gardener’s mydriasis,” or excessive pupil dilation. Sometimes the pupil enlarges until it almost fills the iris, making it difficult to see. The effect is so frightening that it can send people to the emergency room in fear of a brain aneurysm.

One recent case involved a six-year-old girl who fell out of a wading pool in her backyard. Her parents noticed the dilated pupils and rushed her to the hospital. The doctors asked the parents if the child had been exposed to any poisonous plants, and the parents said no. Later, after a batch of medical tests came back negative, the girl remembered that she had grabbed the plant as she fell out of the pool.

The alkaloids in brugmansia and datura can easily be absorbed through the skin or inadvertently rubbed into the eyes, bringing on these temporary but terrifying vision problems.





Go and catch a falling star
Get with child a mandrake root
Tell me where all past years are,
Or who cleft the devil’s foot …

—John Donne

Mandrake may not be the worst thug in the nightshade family, but it certainly has the most fearsome reputation. Aboveground, it is an unimposing little plant with a foot-tall rosette of leaves, pale green flowers, and mildly poisonous fruits that resemble small, unripe tomatoes. But the source of the mandrake’s power lies underground.


Fields; open, sunny areas


Satan’s apple, mandragora

Its long, pointed root can grow three to four feet long and is forked like a carrot grown in rocky soil. Members of ancient civilizations thought that the bifurcated, hairy root looked like a devilish little person, sometimes male, sometimes female. The Romans believed mandrake could cure demonic possession, and the Greeks, thinking it resembled a male sexual organ, used it in love potions. It was also widely believed that the mandrake shrieked when it was pulled from the ground—so loudly that its screams would kill anyone who heard it.

Flavius Josephus, a first-century AD Jewish historian, described one method for surviving the mandrake’s horrible screams. A dog would be tied to the base of the plant with a rope and the owner would retreat to a safe distance. When the dog ran away, it would pull the root up. Even if the screams killed the dog, a person could still pick up the root and use it.

The friar gave Juliet a mandrake-laced sleeping potion so that she would look “like death when he shuts up the day of life.”

Mandrake was slipped into wine to make a powerful sedative useful for playing nasty tricks on enemies. In a battle over the northern Africa city of Carthage around 200 BC, the general Hannibal waged an early form of chemical warfare by retreating from the city and leaving a feast behind, complete with mandragora, a drugged wine made from the mandrake. The African warriors drank and slept, only to be ambushed and killed when Hannibal’s troops returned.

William Shakespeare, perhaps thinking of this event, created a role for the poison in Rorneo and Juliet. The friar gives Juliet a mandrake-laced sleeping potion and makes this grim promise:

The roses in thy lips and cheeks shall fade
To paly ashes, thy eyes’ windows fall
Like death when he shuts up the day of life

Mandrake works its soporific magic through many of the same alkaloids as its deadly nightshade cousins. Atropine, hyoscamine, and scopolamine are all present in the plant and are capable of slowing down the nervous system and inducing a coma.

Recently, an elderly Italian couple arrived at an emergency room, babbling incoherently and hallucinating a few hours after eating the fruit. It took a powerful antidote (ironically, the doctor administered physostigmine, which is derived from the even more toxic Calabar bean), to restore a regular heartbeat and return them to consciousness.

Meet the Relatives The notorious nightshade family includes peppers, tomatoes, and potatoes, along with deadly nightshade and belladonna.






Cannabis has been used by humans for at least five thousand years and regulated or banned for the last seventy. Hemp fibers (from varieties of cannabis that contain very little THC, or tetrahydrocannabinol, and are therefore useless as a drug) have been found in cave dwelling excavations throughout Asia. The Roman physician Dioscorides mentioned the plant’s medicinal properties in his medical guide De materia medica in AD 70. Its use spread to India, throughout Europe, and eventually to the New World, where early settlers grew it as an economically useful fiber crop. Early drafts of the Declaration of Independence were written on hemp paper. It was used in early patent medications, and even sold in Manhattan as a candy from about 1864 through 1900. “Arabian Gunje of Enchantment,” the candy was called. “A most pleasurable and harmless stimulant.”


Sunny, warm, open areas like meadows and fields


Pot, ganja, Mary Jane, bud, weed, grass

This weedy, annual plant grows to ten or fifteen feet tall and produces a sticky, intoxicating resin that is also used to produce hashish. All parts of the plant contain THC, the psychoactive compound that brings on a feeling of mild euphoria, relaxation, and the sense that time is passing slowly. Paranoia and anxiety are sometimes experienced at higher doses, but most effects subside within a few hours. Cannabis is not considered to be a lethal plant except to the extent that it may invite automobile accidents, robberies, and electrical fires from indoor grow operations.

The taxonomy of cannabis is still under debate by botanists. Some argue that Cannabis sativa, C. indica, and C. ruderalis are three separate species, while others believe that C. sativa is the only species in the genus, which may have many different strains. Any of these strains or species may be called hemp or marijuana. In addition to the use of hemp fiber for clothing and paper, hemp has also been investigated as a possible biofuel source, and the seeds are used as a food ingredient because they contain protein, healthy fatty acids, and vitamins.

Marijuana was sold in Manhattan as a candy from about 1864 through 1900. “Arabian Gunje of Enchantment,” the candy was called.

Some historians suggest that the drive to outlaw cannabis in the early twentieth century came out of the culture wars. Recreational marijuana use was popular among jazz musicians, artists, writers, and other ne’er-do-wells. Its use was regulated, but not banned, by the 1937 Marihuana Tax Act. The beginning of the Beat movement may have been the impetus for finally getting this evil weed out of the hands of America’s young people. It was outlawed in 1951 as part of the Boggs Act.

Today marijuana use is banned or strictly regulated in most countries throughout the world. In spite of that, surveys by the U.S. Department of Health show that 97 million people age twelve and over, or roughly a third of Americans, have used marijuana in their lifetime. Thirty-five million, more than 10 percent of the population, have used it in the last year. The United Nations estimates that nearly 4 percent of the world’s population, or 160 million people, consume the drug every year.

Illegal cannabis production is estimated to take up over a half-million acres worldwide and yield forty-two thousand metric tons, making cannabis a roughly $400 billion crop worldwide. U.S. production has been estimated at $35 billion, while the value of the nation’s corn crop is $22.6 billion and that of another wicked plant, tobacco, is only $1 billion. In spite of its value as a cash crop, it’s also still a weed. The U.S. Drug Enforcement Administration reported that in 2005 law enforcement agencies eradicated 4.2 million cultivated plants and over 218 million “ditchweed” plants, which the agency describes as marijuana plants growing wild that are not typically harvested. (Ditchweed is usually a hemp variety left over from the days of legal hemp cultivation.) That means that 98 percent of the United States’ eradication efforts are directed at weeds.

Meet the Relatives Hops (Humulus lupulus), used to flavor beer, are in the same family as cannabis. They have no known intoxicating qualities, although the buds may act as a mild sedative. The hackberry (Celtis spp.) is a related genus of North American ornamental trees.





In AD 77 Pliny the Elder described the oleander as “an evergreen, bearing a strong resemblance to the rose-tree, and throwing out numerous branches from the stem; to beasts of burden, goats, and sheep it is poisonous, but for man it is an antidote against the venom of serpents.”


Tropical, subtropical, and ternperate climates, usually in dry, sunny locations and dry streambeds

Mediterranean areas

Rose laurel, be-still tree

Pliny may have been the most influential botanist of his time, but he was wrong about the oleander. The only relief it would provide a snakebite victim would be a swift and merciful death. This highly toxic shrub is popular in warm climates around the world for its red, pink, yellow, or white blossoms. Because it is so widespread, it has been implicated in a surprising number of murders and accidental deaths over the years. One popular legend is that campers have died after grilling meat over the campfire on skewers made from oleander twigs. This tale is unconfirmed, but the poisons in the sap and bark of oleander could easily contaminate food.

Oleander contains oleandrin, a cardiac glycoside that brings on nausea and vomiting, severe weakness, irregular pulse, and a decreased heart rate that leads quickly to death. It is also toxic to animals: in spite of the leaves’ bitter taste, a cat or dog might be tempted to nibble them. Inhaling the smoke from burning oleander wood can be highly irritating, and even honey made from the plant’s nectar can be poisonous. A study of compost made from oleander showed that oleandrin remains in the compost at detectable levels for three hundred days but that vegetables grown in the compost don’t absorb the toxins.

A woman in Southern California tried to collect on her husband’s life insurance by putting oleander leaves in his food.

Children are particularly at risk because it takes only a few leaves to kill them. In 2000 two toddlers in Southern California were found dead in their cribs after chewing on the leaves. Just a few months later, a woman in Southern California tried to collect on her husband’s life insurance by putting the leaves in his food. He went to the hospital with severe gastrointestinal problems, but he survived. As he was recuperating, his wife finished the job by offering him Gatorade laced with antifreeze. She is now one of fifteen women on California’s death row, and the only one who attempted murder with a plant.

Oleander-related suicide attempts turn up regularly in medical literature; particularly among nursing-home patients, probably because the plant is popular in landscapes and is well known among elderly people as a poisonous plant. In Sri Lanka a related plant called the yellow oleander (Thevetia peruviana) has become the most common method of suicide, particularly among women. Recent studies of the problem sampled over nineteen hundred hospital patients who had poisoned themselves with yellow oleander seeds. Although only about 5 percent of the patients died, the elderly were particularly successful. This may have been due to their frailty, or to their determination, as they tended to ingest more seeds than younger people.

Unfortunately, oleander also has a reputation as a medicinal plant, leading people suffering from certain kinds of cancer or heart problems to attempt an oleander soup or tea from recipes they find online. This practice is very dangerous. Although there have been attempts to market an extract called Anvirzel in the United States, it has not received approval from the U.S. Food and Drug Administration.

Meet the Relatives Other flowering trees and shrubs in the family include the fragrant plumeria; the highly toxic cerbera; the periwinkle; and yellow oleander, Thevetia peruviana.