Wicked Plants: The Weed That Killed Lincoln's Mother and Other Botanical Atrocities - Amy Stewart (2009)
Flesh-eating plants know how to make the best out of a bad situation. Many of them live in bogs and wetlands where nutrition is scarce, so they have developed ingenious ways to trap living creatures for their dinner.
Tiny plants that live in damp soil and water and suck tiny insects and water into bubblelike traps when their trigger hairs are touched. The traps reset themselves within about thirty minutes, making them extraordinarily voracious plants. Some species of bladderworts are large enough to eat mosquito larvae and tadpoles.
Petite, violetlike flowers belie this plant’s carnivorous nature. The leaves exude a slippery ooze that lures fruit flies and gnats to their death. Digestive enzymes excreted by the leaves break down the bodies of the insects, leaving nothing but empty carcasses around the plant.
Perhaps the most familiar carnivorous plant and easy to grow as a houseplant. Their trap leaves stay open and excrete a sweet nectar that attracts insects. Once a fly wanders inside, the trap springs closed. Glands on the insides of the leaves begin to release digestive juices that drown the doomed bug. It can take over a week for a Venus flytrap to devour its prey, and it may only eat a few bugs in its life. Although people can force a trap to close by running a finger along it, carnivorous plant enthusiasts consider this rude.
Nepenthes spp., Sarracenia spp.
Showiest of all carnivorous plants, growing up to a foot tall and producing gorgeous, otherworldly blooms. Americans will recognize the native Sarraceniaceae family, which includes a number of tall, flutelike, bog-dwelling plants with vivid red and white patterns. Insects wander into the flute of the pitcher plant, attracted to the nectar it produces, and drown in the digestive juices that fill the lower regions of the plant. These are sometimes grown as houseplants; it is possible to perform an autopsy on a well-fed specimen by cutting one trumpet-shaped leaf lengthways, exposing a ghastly mass grave of dead flies.
Plants in the Nepenthes genus are also referred to as pitcher plants, but they function a little differently. The plants, which thrive in the jungles of Borneo but are also found throughout Southeast Asia, produce climbing, vinelike stems and cup-shaped flowers that hang from the vine and lure prey. Some of them can hold a quart of digestive fluids. Nepenthes generally feed upon ants and other small bugs, but they’ve been known to indulge in a larger meal from time to time. In 2006 visitors to the Jardin Botanique de Lyon in France complained about a nasty smell in the conservatory. The staff investigated, and found a partially digested mouse inside a large specimen of Nepenthes truncata.
Climbing vines that produce bizarre flowers that vaguely resemble pipes, which is how they got their other common name, Dutchman’s pipe. The Greeks looked at the flower and saw something else: a baby emerging from the birth canal. At that time, plants were often used to treat ailments of the body parts they most closely resembled. Birthwort was given to women to help with difficult labor, but the vine is very poisonous and carcinogenic. It certainly would have killed more women than it helped.
Birthwort lures flies with its strong scent and sticky flowers, but it only traps the flies long enough to make sure they get covered with pollen. The sticky hairs wither, freeing the flies so they can go pollinate other plants.
Nepenthes generally feed upon ants and other small bugs, but they’ve been known to indulge in a larger meal from time to time.
A leaf so toxic that it has taken the lives of ninety million people worldwide; so potent that it can kill through skin contact alone; so addictive that it fueled a war against Native Americans; so powerful that it led to the establishment of slavery in the American South; and so lucrative that it spawned a global industry worth over $300 billion.
Warm, tropical and subtropical, mild-winter areas
Henbane of Peru
This opportunistic little plant contains the alkaloid nicotine that wards off insects. Nicotine has an even more useful function from the plant’s perspective: it is so addictive that humans have been persuaded to grow it in mass quantity. Today tobacco occupies 9.8 million acres around the globe and continues to take 5 million lives a year, making it one of the world’s most powerful and deadly plants. Some 1.3 billion people around the world hold this plant between their trembling fingers every day.
Nicotiana cultivation began in the Americas and dates back to 5000 BC. There is evidence that Native Americans were smoking the leaves two thousand years ago, but it did not spread to the rest of the world until Europeans discovered the practice when they arrived in America. Within a century, tobacco had migrated to India, Japan, Africa, China, Europe, and the Middle East. The leaves themselves, and later “tobacco notes” attesting to the quality of a tobacco crop, were used as legal tender in Virginia. America’s slave trade was born out of a need for more field hands to bring in a profitable tobacco harvest. People didn’t just smoke it; they also believed it could cure migraines, ward off the plague, and ironically, treat coughs and cancer.
But smoking wasn’t embraced by everyone, even in the early days. In 1604 King James I called it “loathsome” and said that it was “harmful to the brain, dangerous to the lungs.” His statement was proven correct time and again over the next four hundred years, but tobacco use only grew.
Nicotine is such a powerful neurotoxin that it’s used as an ingredient in insecticides. Ingesting a leaf is much more harmful than smoking a cigarette because a good deal of the nicotine in cigarettes is destroyed as the cigarette is burned. Nibbling just a few leaves, or making a tea out of the leaves, can quickly bring on stomach cramps, sweating, difficulty breathing, severe weakness, seizures, and death. Prolonged skin contact can also be dangerous: “green tobacco sickness” is an occupational hazard among fieldworkers who must walk through fields of wet tobacco plants in summer.
Nicotine is not the only weapon possessed by plants in this genus. N. glauca, or tree tobacco, grows to twenty-five feet tall and is widespread in California and throughout the Southwest. It is notable for the presence of another toxic alkaloid, anabasine. Ingestion of just a few leaves has caused paralysis and death. A man was found dead in a field in Texas several years ago; the cause of death could not be determined until a mass spectrometry analysis showed the tree tobacco’s poison in his bloodstream.
In spite of its harmful effects, tobacco continues its death march. Enough cigarettes are produced every year to put a thousand smokes into the hands of every man, woman, and child in the world. Other offerings include snuff, chewing tobacco, and the traditional betel quid, which combines Nicotiana with another habit-forming plant, the betel nut. Among some Alaska native tribes, a product called punk ash, or iqmik, is popular; it is made by mixing tobacco with the ash of a burned mushroom that grows on birch trees. Some tribal members believe it to be safer than cigarettes because it is a “natural” product, and it is used by pregnant women and given to children and teething babies. However, the level of nicotine is much higher, and the ash helps deliver it straight to the brain, causing some public health officials to describe it as “freebasing nicotine.”
In India creamy snuff is popular among women. It is sold in a tube like toothpaste and contains not just tobacco, but also cloves, spearmint, and other tasty ingredients. The manufacturer recommends brushing with it morning and night, and “whenever you need,” including when you are “in a state of despair or depressed.” They suggest that you “let it linger before rinsing your mouth.” One satisfied customer testified that she used it eight to ten times a day.
Meet the Relatives This evil weed is a member of the nightshade family. Its more toxic relatives include datura, deadly nightshade, and henbane.
Toxic Blue - Green Algae
Pond scum may not technically be a plant—this particular form of algae is actually classified as a bacterium—but this green creature found throughout the world poses a serious threat to humans and animals. Some species of cyanobacteria, otherwise known as toxic blue-green algae, can reproduce or “bloom” suddenly, releasing poisons into the water. People who drink the water or eat contaminated fish have experienced seizures, vomiting, fevers, paralysis, and death.
Saltwater and freshwater environments worldwide, including oceans, rivers, ponds, lakes, and streams
Everywhere; even present in the fossil record from 3.5 billion years ago
What causes an otherwise normal population of algae to bloom and release their poisons? Scientists are still figuring it out. Fertilizer runoff may play a role, giving the algae something to feed on. Warm temperatures and calm waters encourage the algae to grow, and poisonings do seem to occur more in warm climates during summer months.
Swimming in ponds, lakes, or rivers where algae is visible poses definite health risks. The algae release hepatoxins, which may cause liver failure, and neurotoxins, which may cause paralysis, along with other poisons that cause allergy-like reactions and damage to major organs.
One of the stranger toxins produced by algae is domoic acid. It can bring on gastrointestinal distress, dizziness, and amnesia. Domoic acid poisoning typically occurs when people eat shellfish that have fed off certain species of algae; the syndrome is known as amnesiac shellfish poisoning, or ASP. There is no treatment; so doctors provide whatever relief from symptoms they can and hope that patients recover.
An algae bloom in Brazil killed eighty-eight people and sickened thousands in 1988. Marine biologists in Los Angeles were overwhelmed with sick animals in 2007 when a toxic algae bloom caused sea lions and seals to wash up on the beach in convulsions. Several outbreaks in Australia have sickened people and livestock. But the most notorious incident of all was not understood until recently. In 1961 residents in Santa Cruz, California, awoke to the sound of birds slamming against their homes. Some locals rushed outside with flashlights, only to find dead birds in the street and disoriented, sickened gulls rushing straight at them, attracted by the light.
This story drew the attention of Alfred Hitchcock, who had considered basing a film on a Daphne du Maurier story called “The Birds.” Motivated by the real-life incident, Hitchcock got to work on the film. It took more than forty years for scientists to realize that the bizarre behavior of those seagulls was probably caused by a toxic algae bloom that poisoned anchovies the birds ate.
Meet the Relatives There are thousands of species of algae around the world, many of which are quite beneficial to marine life and humans. One of the best-known cyanobacteria is spirulina (Arthrospira platensis), a popular health food supplement.