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


Dangerous plants don’t just lurk in Amazon rain forests or tropical jungles. They may be widely available at your local garden center but not labeled as poisonous. When in doubt, ask—and remind children not to nibble anything they haven’t already seen at the dinner table. Look no farther than your own backyard for these poisonous beauties:



Rhododendron SPP.


A popular group of shrubs containing over eight hundred species and thousands of varieties. The poison grayanotoxin can be found in the leaves, flowers, nectar, and pollen. Eating any part of the plant can cause heart problems, vomiting, dizziness, and extreme weakness. Honey made from rhododendrons can be toxic, too. Pliny the Elder wondered why Nature would allow the creation of toxic honey and wrote around AD 77, “What, in fact, can have been her motive, except to render mankind a little more cautious and somewhat less greedy?”


Robina psuedoacacia


This North American native tree produces clusters of wisteria-like pink, lilac, or cream-colored flowers, but its branches are covered with sharp thorns and all parts of the plant except the flowers are toxic. The toxin, called robin, is similar to ricin and abrin (produced by castor beans and rosary peas, respectively), and although robin is milder, it can cause a weak pulse, stomach upset, headache, and coldness of the extremities. The bark is especially toxic in fall.


Colchicum spp.


These flowering plants are sometimes called autumn crocus or meadow saffron, but they are neither a true crocus nor the plant from which the spice saffron is derived. The corms produce lovely pink or white flowers in the fall, but all parts of the plant are toxic. They get their poison from the alkaloid colchicine, which causes burning, fever, vomiting, and kidney failure. Colchicum has been used since ancient times as a treatment for gout and was the active ingredient for a common naturopathic medication until a rash of deaths in Oregon in 2007 led to an FDA recall of the drug.


Daphne spp.


Shrubs popular for the tiny clusters of intensely fragrant flowers in winter and early spring when little else is in bloom. Just one or two sprigs will perfume a room. The sap can be irritating to the skin, and all parts of the plant are poisonous. Just a few of the brightly colored berries could kill a child; those who survive may suffer from irritation of the throat, internal bleeding, weakness, and vomiting.


Digitalis spp.


Low-growing biennials and perennials with breathtaking spires of trumpet-shaped flowers in shades of white, lavender, pink, and yellow. All parts of the plant can irritate the skin and cause severe stomach upset, delirium, tremors, convulsions, headaches, and fatal heart problems if ingested. The plant produces the cardiac glycoside digoxin, which is used to prepare the heart drug digitalis.


Helleborus spp.


This low-growing perennial produces dramatic, dark green foliage and beautiful five-petaled blossoms in shades of pale green, white, pink, red, and maroon that appear in winter and early spring. All parts of the plant are poisonous. The sap is irritating to the skin, and symptoms of ingestion include burning of the mouth, vomiting, dizziness, nervous-system depression, and convulsions. The plant was once popular as a medicine; one theory about the death of Alexander the Great was that he had been given a medicinal dose of hellebore. The First Sacred War (595–585 BC) is believed by some historians to have been won after a Greek military alliance poisoned the water supply of the city of Kirrha with hellebore. This would have been one of the first instances of chemical warfare in recorded history.


Hydrangea spp.


A beloved garden shrub prized for its enormous clusters of blue, pink, green, or white flowers, hydrangea contains low levels of cyanide. Although poisonings are rare, the flowers are used as a cake topper, which could lead people to believe it is edible. Symptoms include vomiting, headache, and muscle weakness.


Lantana spp.


A popular, low-growing evergreen perennial that attracts butterflies and blooms all summer long in shades of red, orange, and purple. The berries contain the highest level of toxins while they are still green. If ingested, the berries can cause visual problems, weakness, vomiting, heart problems, and death.


Lobelia spp.


The Lobelia genus contains a number of beloved garden plants, including the compact, brilliant blue L. erinus, a bedding annual that spills out of containers; the spiky bright red L. cardinalis, which thrives in marshes; and the tropical L. tupa, often called devil’s tobacco. One species, L. inflate, or Indian tobacco, has also earned the names pokeweed and vomitwort. The poisons in lobelia, called lobelamine and lobeline, are similar to nicotine and can cause heart problems, vomiting, tremors, and paralysis if ingested.


Gelsemium sempervirens


An evergreen vine native to the American Southwest. The bright yellow, trumpet-shaped, fragrant flowers make it a popular climber and groundcover, and it has been adopted as the state flower of South Carolina. All parts of the plant are poisonous. Children have died from mistaking the plant for honeysuckle and sucking the nectar out of the flowers. Both pollen and nectar can be toxic to bees who visit the plant too frequently when no other flowers are available.



Opium Poppy


The opium poppy is the only Schedule II narcotic (defined as having a high potential for abuse but can still be prescribed) that you can order through a garden catalog, find at a nursery, buy in a floral arrangement, or enjoy in your own flower bed. While possession of opium poppy plants or poppy straw is strictly illegal, most local law enforcement officers will admit that they have bigger problems on their hands than a few pink or purple flowers in Grandma’s garden. Only the seeds of this plant are legal to possess, in recognition of the fact that they are a popular food ingredient.


Temperate climates, sun, rich garden soil

Europe and western Asia

Breadseed poppy, peony poppy, Turkish poppy, “hens and chicks” poppy

Experienced gardeners have no trouble distinguishing the opium poppy from its non-narcotic cousins. The plant’s smooth, bluish green leaves; enormous pink, purple, white, or red petals; and fat blue-green seedpods give it away. When the flesh of freshly harvested seedpods is scored with a knife, a milky sap oozes out. That sap produces opium, which contains morphine, codeine, and other opiates used as painkillers.

Papaver somniferum has been cultivated in the Middle East since about 3400 BC. Homer’s Odyssey mentions an elixir called nepenthe that allowed Helen of Troy to forget her sorrows; many scholars believe that nepenthe was an opium-based drink. In 460 BC, Hippocrates championed opium as a painkiller. Records of its use as a recreational drug date back to the Middle Ages.

Homer’s Odyssey mentions an elixir called nepenthe that allowed Helen of Troy to forget her sorrows; many scholars believe that nepenthe was opium based.

It was combined with a few other ingredients and distributed as a medication called laudanum in the seventeenth century. Doctors extracted morphine from the plant in the early nineteenth century. But the drug company Bayer introduced the most popular extract in 1898 when it created a much more powerful drug from the poppy. The name it coined for its new product? Heroin. Bayer sold it as a cough syrup for children and adults, but it was only on the market for about ten years. Still, the drug-using crowd caught on and started taking heroin recreationally.

An alarming increase in heroin use led the U.S. government to clamp down, and by 1923 it was banned altogether. However, heroin use only continued to grow, and today 3.5 million Americans report having used the drug at some point in their lifetime. The World Health Organization estimates that at least 9.2 million people use heroin worldwide. Afghanistan produces about 90 percent of the world’s opium, but users in the United States primarily get their fix from Colombia and Mexico.

Opium creates a feeling of euphoria but also depresses the respiratory system and can lead to coma and death. It interferes with endorphin receptors in the brain, making it difficult for addicts to make use of the brain’s natural painkillers. This is one of the reasons why withdrawal from heroin is so difficult. Addicts who are thrown into jail and forced to go cold turkey will sometimes throw themselves against the bars of their cell for a distraction from the intense muscle pain. Even tea made from the seeds and seed heads can be dangerous because the level of morphine varies widely from plant to plant: in 2003 a seventeen-year-old Californian died from an overdose of “natural” poppy tea.

It would take an annual harvest of at least ten thousand poppy plants to supply the typical heroin user for a year, but there are no exceptions under the law for gardeners who want to grow the flowers. In the mid-1990s, the DEA asked seed companies to stop selling the seed in their catalogs voluntarily, fearing that the availability of the seeds could contribute to domestic heroin production. Most seed companies ignored the request, and the flower continues to be popular among gardeners. The seeds used in baked goods are harmless in small quantities, but eating a couple of poppy seed muffins could cause a positive result on a drug test.

Meet the Relatives Other poppies include the Oriental poppy, Papaver orientale; the Shirley poppy or Flanders field poppy, P. rhoeas; and the Iceland poppy, P. nudicaule. The orange California poppy is not related; this native wildflower is Eschscholzia californica.