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Throughout history, plants have been an essential part of our lives, offering food, shelter, warmth, fuel, medicine, clothing, textiles, entertainment, and a deep connection with nature. Given the vast number of plant species, it's crucial to recognize their potential toxicity, especially when it involves plants we encounter regularly. Here’s a list of 10 common plants that you might not realize are toxic.
10. Poinsettia Euphorbia pulcherrima
Toxic Component: Diterpene esters found in latex
First on the list is one of the most recognizable ornamental plants, the poinsettia. Scientifically known as Euphorbia pulcherrima, this plant is native to the tropical, deciduous forests of Mexico. Its bright red and green leaves have long been associated with Christmas, although poinsettias can also be grown in a variety of other colors, ranging from blue to pink.
There is a common misconception that poinsettias are extremely poisonous, but this is not the case. The confusion likely stems from the fact that many other plants in the Euphorbia genus are indeed toxic. While consuming poinsettias may lead to symptoms like vomiting and diarrhea, skin exposure can cause temporary eczema, and contact with the eyes may result in short-term blindness. However, these reactions are not always inevitable. According to POISINDEX, a key resource for poison control centers, it would require around 500 leaves of the plant to poison a 50-pound (22.68kg) child. Thus, our first entry on the list.
9. English Ivy Hedera helix
Toxic Components: Triterpenoid saponins and polyacetylene compounds
English Ivy is a highly common plant and is classified as an invasive species in the United States, with its sale and distribution even being banned in Oregon. This is due to its tendency to create “ivy deserts” across landscapes. Hedera helix is notorious for climbing up trees, sometimes causing them to collapse. Although difficult to control, it’s frequently used by gardeners as an edging plant or as an intriguing houseplant.
Young children are often the victims of this plant's toxicity, likely due to their curiosity. Ingesting it can lead to symptoms such as delirium, stupor, convulsions, hallucinations, and fever. Contact with the leaves may result in skin irritation, itching, rashes, and blisters. It makes you wonder why it’s not banned where you are, doesn’t it?
8. Easter Lily Lilium longiflorum
Toxic Component: Lycorine alkaloids
Easter lilies are a well-known species within the Liliaceae family. Native to the Ryukyu Islands of Japan and Taiwan, this lily has become a popular presence in gardens worldwide. Reaching a height of up to one meter (3.28 ft), it produces numerous trumpet-shaped, white, fragrant flowers that face outward, making it a cherished symbol of gardening.
While Easter lilies are undeniably beautiful, they are highly toxic, especially to cats, where the danger is extreme. Humans are also at risk due to the alkaloid Lycorine found in the bulbs and stems. Ingesting parts of the Easter lily, as with nearly all true lilies, can cause symptoms such as abdominal pain, salivation, shivering, nausea, vomiting, and diarrhea. Not exactly what we’d want to experience around Easter, right?
7. Larkspur Delphinium spp.
Toxic Components: Alkaloids delphinine, ajacine, and others
Larkspur is a member of the buttercup family, Ranunculaceae, and is native to North America. It typically thrives at higher elevations, often found in mountainous regions. Ranging from 10 centimeters (3.93″) in height, and reaching up to two meters (6.56 ft) in some alpine species, Larkspur is topped with a raceme of numerous flowers in shades of purple, blue, red, yellow, or white. Almost all species are toxic. Despite this, Delphinium species serve as food plants for the larvae of certain moth species.
Every part of the Larkspur plant is toxic. Due to their height, cattle are frequently poisoned after grazing on them. To minimize risk, many ranchers delay moving cattle into such areas until late summer, when toxicity levels are lower. Symptoms of poisoning include burning sensations in the mouth and lips, throat numbness, severe vomiting and diarrhea, muscle weakness and spasms, a weak pulse, respiratory paralysis, and convulsions, often leading to death. While the plant is visually appealing, it’s best to avoid it.
6. Aloe Vera Aloe Vera
Toxic Components: Aloin and anthraquinone-glycoside
Aloe Vera is a succulent plant known for its long, spiny flower spikes and yellow blooms, which grow in terminal, elongated clusters. For thousands of years, it has been used to treat burns. Additionally, it has been utilized to address conditions like heartburn, diabetes, and irritable bowel syndrome. Aloe vera is commonly added to various cosmetic products such as makeup, tissues, moisturizers, soaps, sunscreens, incense, shaving cream, and shampoos. However, what is not widely known is that aloe vera is actually toxic. While the gel inside the leaves, which is harmless, is surrounded by a thin layer of Aloin and Anthraquinone c-glycoside, both of which are very toxic. If consumed in large amounts, it can cause abdominal cramping, nausea, vomiting, diarrhea, and red urine (without blood). While breaking off a piece to soothe irritated skin is generally safe, individuals sensitive to latex should avoid it.
5. Azalea Rhododendron spp.
Toxic Component: Andromedotoxin
Azaleas are widely found in gardens around the world. Their evergreen leaves and vibrant flowers make them highly attractive to gardeners. The flowers range in color from white to deep pink, red, yellow, purple, blue, and orange.
Despite being widely known, there is a surprising lack of understanding regarding the toxicity of the Rhododendron. Every part of the plant is highly toxic, and consuming any part can prove fatal. Symptoms of poisoning include excessive salivation, watery eyes and nose, abdominal pain, fatigue, depression, nausea, vomiting, diarrhea, weakness, breathing difficulties, paralysis of the limbs, and coma, typically culminating in death. Quite the paradox – beautiful and deadly!
4. Dumb Cane Dieffenbachia
Toxic Components: Calcium oxalate crystals, known as raphides, and oxalic acid
Dumb cane earns its place at number four on this list due to its widespread popularity. Dieffenbachia is an incredibly common houseplant, and it's likely you’ve encountered it in many homes—perhaps even in your own, without realizing its toxicity. The plant contains oxalic acid, a sour compound also found in the edible shamrock (oxalis). Additionally, Dieffenbachia holds tiny, needle-like crystals known as calcium oxalate. Chewing a leaf of this plant causes a severe burning sensation in the mouth, throat, and tongue. It can also result in temporary vocal cord paralysis, earning the name ‘dumb cane.’ Though ingestion isn’t always fatal, victims report excruciating pain and extreme discomfort. Other symptoms include excessive drooling, localized swelling, and difficulty speaking or swallowing, as well as nausea, vomiting, and diarrhea. Think twice before casually passing by this deceptively innocent-looking houseplant!
3. Datura Stramonium
Toxic Components: Tropane alkaloids – atropine, hyoscyamine, and scopolamine
Next on the list is Datura Stramonium, a widely recognized and alluring plant. It thrives in almost any environment with soil, sometimes remaining dormant underground for years before suddenly sprouting when the soil is disturbed. The plant is famous for its trumpet-shaped flowers, which range from white to pink or purple, and its seed pods that are lined with sharp thorns. A foul stench is emitted when any part of the plant is disturbed or broken. Consider its numerous ominous names—Devil’s trumpet, Devil’s weed, Hell’s Bells, locoweed, stinkweed, thornapple, Jamestown weed, and Moonflower. It belongs to the notorious Nightshade family, known for its deadly members.
Datura has had historical significance in various cultures. In North America, it was used as a sacred sacrament by natives, while in South Asia, Hindus associate it with Lord Shiva, often depicted as smoking Datura. The plant induces powerful hallucinations and delirium. Its common name, Jamestown weed, originated in Virginia, where British soldiers were unknowingly drugged with it during an attempt to suppress Bacon’s Rebellion. They were rendered incapacitated for eleven days, appearing to be in a state of madness, which only adds to the plant’s notorious reputation.
"The James-Town Weed (which resembles the Thorny Apple of Peru, and I take to be the plant so call’d) is supposed to be one of the greatest coolers in the world. This being an early plant, was gather’d very young for a boil’d salad, by some of the soldiers sent thither to quell the rebellion of Bacon (1676); and some of them ate plentifully of it, the effect of which was a very pleasant comedy, for they turned natural fools upon it for several days: one would blow up a feather in the air; another would dart straws at it with much fury; and another, stark naked, was sitting up in a corner like a monkey, grinning and making mows [grimaces] at them; a fourth would fondly kiss and paw his companions, and sneer in their faces with a countenance more antic than any in a Dutch droll,"
In this frantic condition they were confined, lest they should, in their folly, destroy themselves – though it was observed that all their actions were full of innocence and good nature. Indeed, they were not very cleanly; for they would have wallowed in their own excrements, if they had not been prevented. A thousand such simple tricks they played, and after eleven days returned themselves again, not remembering anything that had passed." – The History and Present State of Virginia, 1705
Every part of the Datura plant contains dangerous levels of poisonous alkaloids, making it highly toxic and often fatal if ingested by both humans and animals, including livestock and pets. Datura poisoning typically leads to an inability to distinguish reality from fantasy. Other symptoms include hyperthermia, tachycardia, unusual and potentially violent behavior, severe pupil dilation causing painful sensitivity to light that can last for days, and significant memory loss. The margin between a safe dose and a lethal overdose is incredibly narrow, which is why recreational use of Datura stramonium is highly discouraged. Overdose often results in death.
2. Foxglove Digitalis purpurea
Toxic Principles: Cardiac and steroid glycosides
Foxglove is a strikingly beautiful plant, often seen gracing the colorful landscapes of gardens. Its botanical name, digitalis, translates to "finger-life," referencing how easily its bell-shaped flowers can slip over a human finger. These flowers bloom in a tall, spire-like formation and come in hues of purple, pink, blue, white, and yellow, with some exhibiting intricate spots and markings on the inside. Foxglove claims its spot as number two on this list for its combination of beauty, widespread presence, and unmatched toxicity.
Once highly regarded for its ability to treat heart ailments, epilepsy, and other seizure-related conditions, the use of Foxglove is now considered controversial due to the range of severe side effects it can cause. While the whole plant is toxic, it is the leaves of the upper stem that pack the most potent punch. Just a small bite of the plant can be fatal. Initial symptoms of poisoning include nausea, vomiting, diarrhea, stomach pain, vivid hallucinations, confusion, and intense headaches. As the poisoning progresses, it may lead to irregular heart rhythms, slow pulse, tremors, visual disturbances (such as seeing yellow or green hues and blue halos around light), seizures, and ultimately heart failure. Tragically, many who experimented with foxglove have met their end as a result.
1. Oleander Nerium oleander
Toxic Principles: Cardiac glycosides: nerioside and oleandroside; saponins, and other unknown agents
Oleander is a compact but striking plant, known for its variety of colorful flowers. One thing that is widely recognized about this plant is its extremely high toxicity. In fact, just a single leaf can be fatal if ingested by a child or infant. Even after drying, the plant retains its toxic properties. The symptoms resulting from consuming Oleander are both horrifying and severe, which is why it ranks as number three on our list. They include nausea, abdominal pain, dizziness, drowsiness, poor blood circulation to the extremities, seizures, tremors, collapse, slow pulse, irregular heartbeat, dilated pupils, bloody diarrhea, coma, death, and even suicidal tendencies. Yes, you read that correctly. In Southern India, numerous suicide cases have been reported where people ingested mashed oleander seeds. So, the next time you consider adding oleander to your culinary concoction, think twice!
