Beautiful but deadly. Some of nature’s most gorgeous creations can also be some of its most fatal. Don’t be fooled by a delicate blossom or burst of colorful berries – some of these plants can burn, blister, paralyze, or kill.
It’s no accident that many of the world’s most toxic plants are also among the most captivating. Throughout history, we’ve romanticized many of these plants in gardens, art, and folklore. While some flora earn their reputation with fragrance and flair, others are known for their toxins potent enough to hospitalize a grown adult.
In some instances, those features that we consider beautiful can actually be a sophisticated defense mechanism designed to protect the plant. Many of these plants have evolved different features to attract the right allies (pollinators) while deterring the wrong ones (predators like you).
Collecting the Deadly Data and Know-How
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As a Colorado Master Gardener, I’ve compiled a list of 18 of the most poisonous plants that you’ll want to handle with caution.
I’ve collected information from horticultural experts such as Jenny Laville, Digital Editor for Shows with the RHS, Jaymi Heimbuch, writer with Treehugger, Courtney Celley, Digital Strategist at the U.S. Fish and Wildlife Service, and Noelle Clark, writer with Big Blog of Gardening.
Some of these plants are commonly found in people’s yards (hellebores, I’m looking at you!) while others are more unusual.
Proceed with Caution
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If you’re not sure what plants are safe for your yard, first consider who will be in your garden (small children, pets, etc.). If you’re not sure about a certain plant, it’s always best to do your own research or talk to an expert at your local nursery for the best recommendations.
These plants are necessarily off limits by any means. It’s just information that’s good to know so that you can responsibly grow them, if you choose to.
1. Lily of the Valley
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At first glance, Lily of the Valley looks innocent. It is known for its delicate white bells and a fragrance so sweet that it has inspired perfumes.
However, lurking beneath its beautiful exterior are cardiac glycosides, a toxic compound that can slow your heart to a crawl. Even ingesting a small amount can cause dizziness, vomiting, and hospitalization.
2. Foxglove (Digitalis purpurea)
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Foxglove is a gorgeous stunner that also gave us the heart drug digitalis, but don’t be fooled by its medical lineage.
Foxglove is so potent that ingesting just a couple of leaves could trigger arrhythmia (an irregular heartbeat), nausea, and even cardiac arrest. It’s also toxic to pets, so keep your furry friends away from this one!
3. Oleander
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Used widely in parks and medians because it is drought-tolerant, oleander can be a stealth killer. Every single part of this evergreen shrub is toxic, even its smoke, if burned.
Oleander has been known to kill livestock, children, and adults with the smallest of doses.
4. Delphinium and Larkspur
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Towering, vibrant, and seemingly regal, delphinium and larkspur contain alkaloids, which belong to a class of nitrogenous organic compounds that can have a pronounced physiological reaction in humans.
Symptoms of poisoning range from mild stomach upset to paralysis and death. These plants are especially dangerous to grazing animals, but humans aren’t immune either. Avoid touching these plants when sweaty or with open cuts.
5. Bleeding Heart
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Commonly known as a symbol of unrequited or lost love, the bleeding heart has an even more sinister truth.
Its roots and foliage are toxic (though not usually fatal) if ingested, and may cause tremors and convulsions. It’s best to admire this plant from afar.
6. Belladonna
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Belladonna’s reputation precedes her. It has been used for centuries in assassinations, cosmetics, and folklore. It only takes a few berries to poison a child, and even handling its foliage can introduce toxins through cuts and mucous membranes.
The effects of Belladonna poisoning include dilated pupils, dry mouth, delirium, and potentially death.
7. Jimson Weed and Datura
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Wild, invasive, and dangerously misunderstood, these hallucinogenic plants contain scopolamine and atropine, which can cause delirium, amnesia, and hallucinations.
Some people touch them thinking they’re harmless wildflowers, only to end up in the emergency room with a racing heart and out-of-body confusion.
8. Tobacco and Bitter Nightshade
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Although tobacco is legal (and heavily processed for use), the raw plant contains lethal alkaloids that can be especially toxic to pets or livestock. Bitter nightshade offers similar effects, and can often be found climbing along fences or creeks with shiny berries that tempt curious hands and paws alike.
Alkaloid-bearing plants like tobacco and bitter nightshade can cause skin irritation and are known to disrupt everything from nerve signals to cardiac rhythms.
9. Autumn Crocus
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Autumn crocus contains colchicine, a toxic compound that disrupts cell division. Ingesting even a small amount can lead to severe gastrointestinal distress, organ failure, or death.
Be careful not to confuse autumn crocus with saffron crocus, which is an edible plant. That’s a mistake you would definitely regret making.
10. Angel’s Trumpet (Brugmansia)
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Angel’s Trumpet is a tropical showstopper with hanging, trumpet-shaped blooms. Its beauty is matched by a cocktail of toxic alkaloids, which includes scopolamine, atropine, and hyoscyamine.
All parts of the plant are poisonous, and exposure can cause hallucinations, paralysis, and respiratory failure. Some gardeners call it “zombie tea” for this reason.
11. Hellebore
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The appearance of this early-spring bloomer is often the first sign that the clutches of winter are waning. However, ingestion of Hellebore can cause vomiting, dizziness, and a slowed heart rate. Even skin contact can trigger mild burning or tingling.
Because hellebores are fairly common in home landscaping, it’s best to keep these away from children or pets, and handle them with gloves only.
12. Snowberry
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This plant looks like something out of a holiday card, because of its round, white berries framed against an ethereal, frosty branch. However, don’t be fooled by those sweet-looking little berries – they are toxic to both humans and animals.
Ingesting snowberry is not lethal in most cases, but it can cause nausea or vomiting.
13. Castor Oil Plant (Ricinus communis)
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You’ve likely heard of castor oil due to its prominence as a common remedy for many ailments. However, its seeds, called castor beans, contain a deadly toxin known as ricin. Just one chewed seed of ricin is capable of killing a child.
The protein in ricin disrupts cell metabolism, eventually leading to multisystem organ failure. Unfortunately, there is no known antidote.
14. Rosary Pea (Abrus precatorius)
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The vibrant red-and-black seeds rosary pea, a tropical vine, contain a potent toxin called abrin. While intact abrin seeds may pass through the digestive system without incident, any cracked or chewed seed is enough to cause death.
They’re beautiful, deadly, and sometimes sold online without warning for homemade jewelry-making purposes. Buyer beware!
15. Manchineel Tree (Hippomane mancinella)
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This Caribbean native is so dangerous that trees are often marked with warning signs or red paint (thankfully, so watch out for a red sign if you’re on vacation and wandering!). The sap can cause skin blistering on contact, blindness if it enters the eyes, and severe internal damage if ingested.
Even standing under a manchineel tree during rain can cause burns, as water carries the sap to your skin. For these reasons, it’s earned the name “Little Apple of Death.”
16. Giant Hogweed (Heracleum mantegazzianum)
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Giant Hogweed is familiar in its appearance, closely resembling an oversized Queen Anne’s lace. However, touch it and you’re in trouble.
The sap contains furanocoumarins, a toxin that can make your skin hypersensitive to sunlight. As a result, you may suffer from third-degree burns, blistering, and even permanent scarring.
17. Water Hemlock and Poison Hemlock
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Water hemlock and poison hemlock are among the most lethal plants in North America, though they are frequently confused with wild carrot or parsley.
A single bite of either plant can cause seizures, respiratory failure, and death. Both hemlock varieties are commonly found along creeks and trails in North America, so be careful if you’re out exploring!
18. Gympie-Gympie (Dendrocnide moroides)
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Native to Australia and arguably the most painful plant in existence, this stinging tree is covered in tiny silica needles laced with a neurotoxic venom.
Touch it, and you’ll feel a burning pain that can last for weeks or even months. Some stings have required hospitalization. It’s best to keep your distance from this one.
When in Doubt, Admire From a Distance
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There’s no denying the allure of many of these plants. Some of them are bold, others delicate, and many are absolutely, show-stoppingly beautiful. However, regardless of their allure, we should all probably keep our distance. It’s best to think twice about planting one of these in your yard, especially if you have curious kids or pets running around.
And, if you’re ever in London, I highly recommend a visit to the Chelsea Physic Garden. They maintain a unique, living collection of historical, medicinal plants that has been continuously cultivated since the 1600s. Many of the plants on this list are part of their collection due to their use by apothecaries, herbalists, shamans, and healers around the world throughout history. It’s a must-visit!
