by Amy Stewart
They are also so toxic that a single seed, chewed well, would kill a person. In fact, punching holes in the hard shells to run a piece of string through the seeds puts a jewelry maker at risk: a finger prick with a needle in the presence of even small quantities of rosary pea dust could be fatal, and inhaling the dust is risky, too.
The poison at work within rosary peas is abrin, which is similar to ricin, found in castor beans. Abrin attaches itself to cell membranes and prevents cells from making protein, which kills them. It can take a few hours or even a few days for symptoms to appear, but when they do, the unfortunate victim will be beset by nausea, vomiting, cramps, disorientation, convulsions, liver failure, and after a few days, death. Unfortunately, the colorful seeds are attractive to small children. As an Indian doctor warned, the rosary pea will “kiss a child to death.”
Meet the Relatives Abrus melanospermus and A. mollis are reported to have some medicinal uses, particularly for skin wounds and bites, but not enough is known about their toxicity.
PAINFUL
THE TERRIBLE TOXICODENDRONS
Poison ivy, poison oak, and poison sumac occupy nearly every state in the Union. But most people don’t realize how truly evil toxicodendrons can be.
POISON IVY
Toxicodendron radicans
POISON OAK
Toxicodendron diversilobum, others
POISON SUMAC
Toxicodendron vernix
Poison ivy is not, technically, an ivy. Poison oak is not an oak. Poison sumac has nothing to do with sumac trees. And by the way, none of them are poisonous.
The irritating oil they produce, urushiol, is not at all toxic, but it does happen to be an oil that most people are highly allergic to. Oddly enough, only humans are bothered by exposure to urushiol. No one knows why the plants have singled out people for their unique form of vitriol. Because urushiol creates an allergic reaction—which is nothing more than the immune system gone haywire, fighting some harmless substance, like Don Quixote charging at windmills—each subsequent exposure is worse than the one before. The immune response gets stronger, so that the reaction gets worse with each repeated exposure.
Someone who has experienced a severe poison ivy outbreak could be very sensitive to the rind of the mango fruit or other parts of the tree.
Roughly 15–25 percent of the population is not at all allergic to toxicodendrons and will never develop a reaction. Another small slice of the population could develop a rash but would need prolonged, intimate contact with the plant to bring it on. But unfortunately, about half of all people will break out if they brush up against the plant, and some of them are so allergic that they may require hospitalization. They are called “exquisitely sensitive” by botanists and physicians.
Those sensitive to poison ivy, poison oak, or poison sumac will break out into an oozing, unbearable rash. Since the oils can persist in sleeping bags, on clothing, and in the fur of adorable little dogs, you may not realize that you’ve been exposed until it’s too late. It can take several days for the rash to appear. Once it does, reactions last two to three weeks. Oatmeal baths may be soothing, and the worst cases may require a shot of steroids, but most victims simply wait it out. Fortunately, reactions are not contagious. Those sores will probably get you banished to the couch, but they will not infect the rest of the family.
Even the most common poison ivies and poison oaks are difficult to recognize. Campers can use a simple trick to identify plants containing urishiol: carefully wrap a piece of white paper around the stem or leaf of the plant in question, crushing the plant without coming into contact with it. If the plant contains urishiol, a brown spot will appear quickly on the paper and turn black within a few hours.
If you’ve had an allergic reaction to poison ivy, oak, or sumac, you’re much more likely to have a reaction to some of their relatives, including:
CASHEW TREE
Anacardium occidentale
The nuts are only safe to eat if they have been steamed open. The oils in the tree, including the fruit from which the nut dangles (called the cashew “apple”), can cause a breakout that looks just like a poison oak reaction.
MANGO TREE
Mangifera indica
Produces a volatile oil everywhere except the inside of the fruit. Someone who has experienced a severe poison ivy outbreak could be very sensitive to the rind of the fruit or other parts of the tree.
LACQUER TREE
Toxicodendron vernicifluum
Used for centuries to produce lacquer and varnish, but it is extremely difficult to work with and a real hazard to workers. Even lacquer found in ancient tombs has caused a rash.
DANGEROUS
Sago Palm
CYCAS SPP.
Gardeners from Florida to California know the sago palm. It is a very tough, slow-growing tree that is widely used as a feature plant in landscapes. The most common variety, Cycas revoluta, is a popular houseplant and is often found in botanical garden conservatories. What most people don’t realize is that all parts of the plants, especially the leaves and seeds, contain carcinogens and neurotoxins. Pets are routinely poisoned by nibbling on the plant, and it has been responsible for widespread cases of human poisoning as well.
FAMILY:
Cycadaceae
HABITAT:
Tropics, some desert environments
NATIVE TO:
Southeast Asia, Pacific Islands, and Australia
COMMON NAMES:
False sago, fern palm, cycad
The best-known incident of poisoning occurred in Guam. Locals made a flour from the seeds of the related false sago palm, C. circinalis. The traditional method involved leaching the poison out by soaking the seeds in water, but food shortages during World War II may have forced people to eat the seeds without first treating them properly. The poisonous compounds have also been found in bats, which the people of Guam considered a delicacy. The food shortages during the war, combined with the availability of guns when military personnel were stationed there, meant that bats were also hunted and eaten more frequently during that time.
Today scientists believe that this caused the mysterious variant of ALS, or amyotrophic lateral sclerosis (also known as Lou Gehrig’s disease) that occurred on the island after the war. This peculiar form of ALS included the nerve degeneration common to ALS, the tremors associated with Parkinson’s disease, and some symptoms that were similar to Alzheimer’s. Medical experts named the syndrome Guam disease and watched helplessly as it became the leading cause of death among native adults living on the island. British veterans and POWs who spent time on the island during the war also had exceptionally high rates of Parkinson’s later in life. As the standard of living improved on the island, and people began to eat a more Western-influenced diet, the syndrome all but disappeared.
The American Society for the Prevention of Cruelty to Animals has identified sago palm as one of the most toxic plants that pets may encounter. Just a few seeds can lead to gastrointestinal problems, seizures, permanent liver damage, and death. The palm is especially harmful to dogs that are tempted to nibble leaves and gnaw on its base. In spite of its name, the sago palm is not actually a palm tree. It is a gymnosperm, which means that it produces seed cones similar to those produced by conifers.
Meet the Relatives Cycas is the only genus in this family. Some are rare and sought after by collectors. These plants are extremely ancient; some show up in the fossil record sixty-five million years ago.
DANGEROUS
MORE THAN ONE WAY TO SKIN A CAT
Some animals are clever enough to avoid plants that are bad for them, but what are the chances that yours is one of them? A pet bored or confined for long periods of time may be tempted to nibble on one of these common plants. The poison control center for the American Society for the Prevention of Cruelty to Animals gets close to ten thousand calls annually regarding plant poisonings. In addition to sago palm, any of the following plants may cause a pet owner’s favorite symptoms,
vomiting and diarrhea, and some are even fatal. Here are some other ill effects:
ALOE
Aloe vera
Although useful for treating burns and scrapes, the saponins found in the plant can cause convulsions; paralysis; and severe irritation of the mouth, throat, and digestive tract.
DAFFODIL AND TULIP
Narcissus spp. and Tulipa spp.
Bulbs contain a variety of toxins that can cause severe drooling, depression, tremors, and heart problems. The scent of bulb fertilizers, which are made with bonemeal, can prove to be too much for some dogs, who might dig up a newly planted bed and chew on a few bulbs before realizing their terrible mistake.
DIEFFENBACHIA
Dieffenbachia spp.
Common houseplant, also called dumbcane. Contains calcium oxalate crystals that can burn the inside of the mouth, cause drooling and swelling of the tongue, and possibly lead to kidney damage.
KALANCHOE
Kalonchoe blossfeldiana
A small succulent with bright red, yellow, or pink flowers often sold as a blooming indoor plant. It contains a class of cardiac steroids known as bufadienolides that can cause heart damage.
LILIES
Lilium spp.
All parts of lilies are toxic to cats, causing kidney failure and death within twenty-four to forty-eight hours. Think twice before bringing a potted Easter lily into the house, and keep floral arrangements containing lilies well out of reach of your whiskered friends.
MARIJUANA
Cannabis sativa
Marijuana can depress a pet’s nervous system and lead to seizures and comas. If you have to take your stoned pet to the vet for treatment, fess up so the animal gets the right care. Don’t worry: vets are used to the “it belonged to my roommate” story.
NANDINA
Nandina domestica
Also called heavenly bamboo, this ornamental shrub produces cyanide, causing seizures, coma, respiratory failure, and death.
All parts of lilies are toxic to cats, causing kidney failure and death within twenty-four to forty-eight hours.
PAINFUL
Stinging Tree
DENDROCNIDE MOROIDES
The diminutive stinging tree has been called the most feared tree in Australia. It reaches about seven feet in height and produces tempting clusters of red fruit that resemble raspberries. Every inch is covered with fine silicon hairs that resemble peach fuzz and contain a virulent neurotoxin. Simply brushing up against the plant results in unbearable pain that may last up to a year. In some cases, the shock of the pain can be so great that it brings on a heart attack.
FAMILY:
Urticaceae
HABITAT:
Rain forests, particularly in disturbed areas, in canyons, or on slopes
NATIVE TO:
Australia
COMMON NAMES:
Gympie gympie, moonlighter, stinger, mulberry-leaved stinger
The hairs themselves are so tiny that they easily penetrate the skin and are almost impossible to pull out. The silicon does not break down in the bloodstream, and the toxin itself is surprisingly strong and stable. In fact, it remains active even in old, dry specimens of the plant. The pain can be reactivated for months afterward by extreme hot or cold, or simply by touching the skin. Even walking through the forest where stinging trees are present can pose a threat. The tree sheds its fine hairs constantly, and passersby run the risk of inhaling them or getting them in the eyes.
A soldier remembers being stung by the tree during his training in 1941. He fell right into the plant, coming into full body contact with it. He was tied to his hospital bed for three weeks in pure agony. Another officer was stung so badly that he committed suicide to get away from the pain. Humans are not the only ones affected—newspaper accounts from the nineteenth century include reports of horses dying from the sting.
Simply brushing up against a stinging tree plant results in unbearable pain that may last up to a year. In some cases, the shock of the pain can be so great that it brings on a heart attack.
Anyone walking through the Australian rain forest would be well advised to keep an eye out for this plant. It can easily penetrate most kinds of protective clothing. A common treatment is the application of a hair removal wax strip, which will pull out the plant’s fine hairs along with your own. Experts recommend a shot of whisky before attempting this treatment.
Meet the Relatives The stinging tree is part of the nettle family; the genus includes Dendrocnide moroides, believed to be the most painful. D. excelsa, D. cordifolia, D. subclausa, and D. photinophylla are also referred to as stinging trees.
PAINFUL
MEET THE NETTLES
How much could the tiny, fine hairs on a nettle possibly hurt? Those delicate trichomes act as hypodermic needles, injecting venom under the skin when you brush against them. Urticaria, the medical term for intense, painful hives, gets its name from the Latin word for nettle, urtica.
Although any number of painful plants are referred to as nettles, true nettles come from the family Urticaceae. They are mostly weedy perennials that spread by underground rhizomes, and they make themselves at home throughout North America, Europe, Asia, and parts of Africa. A variety of compounds deliver the nettle’s sting, including a muscle toxin called tartaric acid, as well as oxalic acid, which is found in a number of fruits and vegetables and can irritate the stomach. Formic acid, a component of bee and ant stings, is also present in nettles at low levels.
Fortunately, there’s a folk remedy for nettle stings: nettle juice. That’s right, the sap from the crushed leaves is believed to counteract the acidity of the sting. Dock, a weed that often grows near nettles, may also soothe a nettle sting—and dock leaves are blissfully free of sharp, poisonous spines. There’s little evidence about the effectiveness of these remedies, but experts agree that the task of looking for a dock leaf might take one’s mind off the pain.
The news on nettles is not all bad: young nettle shoots, when boiled to remove the hairs, are a nutritious spring delicacy, and sufferers of rheumatism have tried deliberately stinging themselves with nettles to relieve their joint pain. There is even a name for this deliberate flogging of oneself with nettles: uritication.
STINGING NETTLE
Urtica dioica
The best-known nettle, growing widely throughout the United States and northern Europe wherever it can find moist soils. A herbaceous perennial, it reaches about three feet in height in summer and dies back to the ground in winter.
DWARF NETTLE
Urtica urens
An annual, low-growing herb considered by some to be the most painful plant in the United States. Also called lesser nettle or burning nettle. Grows in most of Europe and North America.
TREE NETTLE OR ONGAONGA
Urtica ferox
One of New Zealand’s most painful plants. Causes rashes, blisters, and intense stings lasting several days. There have been reports that full-body contact with the plant has killed dogs and horses, perhaps from the systemic allergic reaction of anaphylactic shock.
NETTLE TREE
Urera baccifera
Found in South America from Mexico to Brazil. Ethnobotanists have reported that the Shuar of the Ecuadorian Amazon use the stinging leaves to punish their children when they misbehave.
TREE NETTLE
Laportea spp.
Grows in tropical and subtropical regions of Asia and Australia. Unlike most nettles, the sting can last for weeks or months and it can cause breathing trouble. Old, dry branches that have been sitting around for several decades can still do harm.
DEADLY
Strychnine Tree
STRYCHNOS NUX-VOMICA
Dr. Thomas Neill Cream was a nineteenth-century serial killer who favored strychnine, which comes from the seed of a fifty-foot-tall tree. Those seeds work well for killing rodents and other household pests—strychnine is also used as rat poison—and Cream discovered that it was effective on tiresome spouses and lovers, too.
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FAMILY:
Loganiaceae
HABITAT:
Tropical and subtropical climates; prefers open, sunny areas
NATIVE TO:
Southeast Asia
COMMON NAMES:
Strychnine, nuxvomica, quaker button, vomit nut
He got his start in Canada, where he was forced to marry a woman at gunpoint after she became pregnant. He ran off just after the wedding but later returned to Canada. Shortly after he returned, she died mysteriously. He had an affair in medical school that also ended with the death of the young woman.
Later he set up a practice in Chicago. While he was there, a man died of strychnine poisoning, and the man’s wife ratted out Dr. Cream for providing the poison rather than serve time herself.
But that didn’t stop him. Ten years later, Cream was out of jail and offering medical services to unfortunate young women in London whose deaths were often blamed on other ailments such as alcoholism. But the true cause of death was the powdered strychnine seed he slipped in their drink. Dr. Cream’s pride in his work led him to brag about his accomplishments, and that led to his arrest. By the age of forty-two, he was tried, convicted, and hanged.