June 18, 2024

Poisonous Plants: 31 Varieties That Can Cause Harm

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There are many common plants in our gardens that have the potential to harm. Learn which to watch for in our guide to poisonous plants on Gardener’s Path.

A vertical image of a dumb looking cat taking a bite out of a plant in a pot. To the top and bottom of the frame is green and white printed text.Poisonous Plants: These 11 Common Varieties May Pose a Health Risk to Children and Pets | Gardenerspath.com

We all want to keep our pets and kids safe, and part of that process is knowing what to watch out for.

You’d be amazed how many plants out there are potentially poisonous. Some might cause just a bit of skin irritation, others could kill you.

Still other plants are perfectly edible and should be devoured as often as possible. Knowing which is which can make all the difference.

Of course, nothing in the world is entirely black or white and there is no such thing as a “bad” or “good” plant. The most poisonous plants on this list are used to make life-saving medication.

A vertical image of a dumb looking cat taking a bite out of a plant in a pot. To the top and bottom of the frame is green and white printed text.A vertical image of a dumb looking cat taking a bite out of a plant in a pot. To the top and bottom of the frame is green and white printed text.

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So before we go through the list, let’s try to gain a little perspective. Poisonous plants account for a tiny number of toxin exposures.

In a review of calls over seven years to a southwestern poison control center published in the Journal of Medical Toxicology in 2018, just 0.79 percent of calls were about human exposure to toxic plants.

Of these, 94 percent were managed at home, and only 37 (0.6 percent) required that the individual be admitted to the hospital.

The majority of exposures involved accidental ingestion (58.3 percent) while at home, followed by dermal exposure (34.3 percent). Cacti accounted for the most encounters at 27.5 percent, with oleander species far behind at 12.5 percent.

So while there are poisonous plants out there that can cause serious harm, the actual risks aren’t as extreme as we might imagine.

You also need to decide what level of potential exposure you’re willing to tolerate.

If you have a pair of garden gremlins that eat their way through your veggie patch, you might want to avoid any plants that are only partially edible, like rhubarb, or those that look like edible plants, like castor beans.

But if your dogs are like mine, they are extremely choosy about which blade of grass they’ll nibble on as their after-meal snack.

I feel safe growing several so-called “extremely poisonous” specimens like yews and rhododendrons because I’m confident that my picky eaters won’t be sampling them anytime soon.

But if you have a curious toddler who puts everything in their mouth, you might want to keep the tempting red “berries” of the yew out of your yard.

While there have been very few serious or fatal yew poisonings in recent decades, only you can decide if it’s worth exchanging the evergreen splendor for peace of mind.

For livestock owners, you have to be even more cautious. Yew poisoning is not infrequent in livestock. Grazers aren’t as cautious and picky as cats, dogs, and humans.

So, in this guide, we’re going to review a pretty comprehensive list of potentially poisonous plants that people cultivate often in the garden.

But inclusion on this list doesn’t mean that you shouldn’t, under any circumstances, grow it.

Even tomato plants are poisonous, and pretty much no one is suggesting that we should keep them out of our gardens.

In other words, this is a list of plants that have the potential – sometimes remote – to be dangerous. But it’s not an admonition to avoid these species. Some are even edible in small amounts or when prepared correctly.

However, if you find your child or pet gnawing on a plant and you find it on this list, it’s worth a call to the Poison Control Center or 911, particularly if you see any symptoms developing. Call 1-800-222-1222 in the US.

31 Poisonous Plants That May Cause Harm

  1. Aconite
  2. Aloe
  3. Amaryllis
  4. Anemone
  5. Angel’s Trumpet
  6. Asparagus Fern
  7. Autumn Crocus
  8. Azalea
  9. Castor Bean
  10. Chinese Lantern
  11. Chrysanthemum
  1. Delphinium
  2. Dieffenbachia
  3. English Ivy
  4. Foxglove
  5. Honeysuckle
  6. Hydrangea
  7. Jimson Weed
  8. Lantana
  9. Lily
  10. Lily of the Valley
  1. Morning Glory
  2. Mountain Laurel
  3. Narcissus
  4. Oleander
  5. Rhododendron
  6. Rhubarb
  7. Sago Palm
  8. Snake Plant
  9. Wisteria
  10. Yew

Remember, the poison is in the dose. If your child wants to try some chrysanthemum petals on their salad with the rest of the family and there are no known allergies, toss ‘em on!

But if you had a big old patch of mums that is suddenly missing, and you find your small dog panting next to it, it’s a different story.

Kids and pets are really the major worry with most of these plants because they don’t know any better when it comes to which may or may not be safe to eat, and they have smaller bodies. Supervision will go a long way towards safety in the garden.

1. Aconite

You might have heard of monkshood or wolfsbane (Aconitum spp.).

The beautiful – and deadly – plant appears in Greek myths, and novels like “Dracula” and “Harry Potter,” and often features in recipes for magic potions.

Good old aconite has a notorious past and continues to be used in homeopathic medicine by those who know what they’re doing.

A close up horizontal image of the blue flowers of poisonous monkshood growing in the garden.A close up horizontal image of the blue flowers of poisonous monkshood growing in the garden.

But if a kid or pet stumbled onto a patch and decided to give it a nibble, the results would be decidedly unmagical.

The alkaloid toxin aconitine causes facial numbness and paralysis, muscle weakness, and can lead to heart attacks. Smaller amounts cause nausea, vomiting, and diarrhea.

Monkshood poisoning can and does happen, usually by people attempting to use it medicinally, but also when people ingest the berries or leaves after misidentifying them.

2. Aloe

What’s the number one succulent that’s soothing to humans, but dangerous to a dog or cat?

The answer is aloe vera, part of the Liliaceae family. It’s been used medicinally since ancient times in India, Rome, Egypt, Greece, and China, and has been referred to as the “first aid plant.”

A horizontal image of an Abyssinian cat munching on the leaf of an aloe vera plant, pictured on a soft focus background.A horizontal image of an Abyssinian cat munching on the leaf of an aloe vera plant, pictured on a soft focus background.

Its magic has been used to heal burns, wounds, frostbite damage, and allergies, and even for improving the immune system.

But while many people take aloe internally, particularly in some Asian and Hispanic cultures where it’s consumed as a healthful drink, some aloes can be toxic.

There are more than 250 species in the world, and most are nontoxic.

But a few, like A. aageodonta, A. ballyi, A. christianii, A. elata, A. ruspoliana, A. striata, and A. verigata can be poisonous.

You wouldn’t want to make a drink out of any of these species. These contain a high ratio of chromone, anthraquinone, and anthrone, which are dangerous in large doses.

The latex of all species, including aloe vera, can also be harmful if consumed in large quantities.

Of course, it would take a lot of work to ingest that much latex, but now you know. Just in case your cat is particularly fond of aloe leaves.

Learn more about aloe vera in our guide.

3. Amaryllis

As cheerful as the blossoms of amaryllis flowers (Hippeastrum spp., formerly Amaryllis spp.) are, the plant contains lycorine, which can cause vomiting, diarrhea, gastroenteritis, dark brown urine, and even death.

A close up horizontal image of an amaryllis bulb in a small pot set on a table outdoors.A close up horizontal image of an amaryllis bulb in a small pot set on a table outdoors.

There probably isn’t much risk of your child or pet grazing on the flowers, but the real danger is if you store the bulbs indoors during the winter for forcing.

Someone might mistake them for onions or think they have a tasty look about them. The toxins are concentrated in the bulb.

You can learn more about amaryllis in our growing guide.

4. Anemone

Anemones (Anemone spp.) are native across North America, Europe, and Asia, and many cultivars can be found in gardens across the world.

Of the 200 or so species, all of them are toxic to some degree.

A close up horizontal image of pink anemone flowers growing in the garden pictured on a soft focus background.A close up horizontal image of pink anemone flowers growing in the garden pictured on a soft focus background.

If you were to eat any part, the protoanemonin contained in anemones would cause severe pain in your mouth, along with vomiting, diarrhea, and stomach pain.

The risk of poisoning is fairly low with this plant, not because it isn’t toxic, but because the intense pain it causes is an excellent deterrent to further consumption.

Check out our growing guide to learn more about anemones.

5. Angel’s Trumpet

With long, pendulous, yellow, white, orange, or pink flowers that you could definitely see an angel trumpeting, Brugmansia candida is always eye-catching.

In combination with the heady fragrance that’s released at night to attract pollinators, it’s a feast for the senses.

A close up horizontal image of angel's trumpet flowers growing in the garden pictured on a soft focus background.A close up horizontal image of angel\'s trumpet flowers growing in the garden pictured on a soft focus background.

Make sure it’s not your mouth that’s participating in the feast. Every part of this nightshade-family plant is poisonous.

Like the closely related belladonna, angel’s trumpet contains atropine, scopolamine, and hyoscyamine. All three block neurotransmitters that impact the heart, digestive system, and nervous system.

People have used this species in folk medicine and as a hallucinogenic.

On top of auditory and visual hallucinations, it can cause confusion, delirium, weakness, paralysis, memory loss, and even death. Sounds like this plant should be renamed the devil’s trumpet, right?

Just enjoy it safely in the garden and keep it away from curious critters and kids, and it can continue to be a heavenly addition to your space.

6. Asparagus Fern

I know there’s a reference to an edible plant in the name, but don’t eat asparagus fern (Asparagus setaceus and A. densiflorus)!

A close up horizontal image of the foliage of an asparagus fern plant pictured on a soft focus background.A close up horizontal image of the foliage of an asparagus fern plant pictured on a soft focus background.

Asparagus fern, which is neither a fern, nor asparagus, is so-named because it looks like the foliage produced by asparagus plants.

Though they’re closely related, you don’t want to eat asparagus fern because it contains the glycoside sapogenin, which can cause vomiting, abdominal pain, and diarrhea if you eat enough of it.

Keep the airy, delicate foliage in the garden or as a houseplant and not on your plate.

Learn more about asparagus ferns here.

7. Autumn Crocus

Autumn crocuses (Colchicum spp.) aren’t true crocuses (Crocus spp.).

The plants definitely share a resemblance, but while a certain species of the latter produces the valuable spice we know as saffron, the former is poisonous.

A close up of pink and purple autumn crocus flowers growing in a sunny fall garden.A close up of pink and purple autumn crocus flowers growing in a sunny fall garden.

Crocuses come from the lily family (Liliaceae) and contain the toxic alkaloid colchicine. While this alkaloid is used in several medications, a small amount is enough to kill a child or dog.

Symptoms include dehydration, gastroenteritis, respiratory stress, vomiting, and cardiac arrest, and consumption has proven fatal.

Learn more about autumn crocus in our growing guide.

8. Azalea

Azaleas (Rhododendron spp.) are pretty hard to ignore.

Those neon-bright flowers last for weeks, and some are so fragrant that kids or pets might be drawn to them for a sweet treat – but azaleas are toxic.

A close up horizontal image of pink azaleas growing in the garden.A close up horizontal image of pink azaleas growing in the garden.

Sucking the nectar, eating the leaves or petals, or consuming honey made using the nectar can all cause adverse symptoms.

Symptoms from ingesting the grayanotoxin glycosides contained in the plant include diarrhea, weakness, vomiting, and collapse. While rarely fatal, it could be if enough is ingested.

You can find more information about azaleas here.

9. Castor Bean

Every now and then, someone in popular culture catches onto the high toxicity of the beautiful castor bean bush (Ricinus communis).

Just ask fans of Breaking Bad and Agatha Christie novels.

A close up horizontal image of the flowers and foliage of a castor oil plant pictured on a soft focus background.A close up horizontal image of the flowers and foliage of a castor oil plant pictured on a soft focus background.

The plant contains ricin, a lectin so toxic that it was investigated as a biological warfare agent and has been used in several confirmed assassination attempts (and some successful assassinations).

Two dozen beans are enough to kill a full-grown adult, and much less will harm a child or pet.

Depending on the dose, ricin causes pain, difficulty swallowing, vomiting, diarrhea, hemorrhaging, organ failure, and death.

10. Chinese Lantern

Kids and adults alike find the papery orange calyces of the Chinese lantern (Physalis alkekengi) whimsical.

Just don’t try to eat them or any other part of the plant, except perhaps the ripe berries.

A close up horizontal image of the fruits of a Chinese lantern plant.A close up horizontal image of the fruits of a Chinese lantern plant.

Chinese lanterns are in the nightshade family, and similar to tomatoes, potatoes, and eggplants, only the mature fruits are edible.

As with other nightshades, they contain solanine and other solanidine alkaloids that cause headaches, stomach pain, vomiting, diarrhea, slowed breathing, and death.

That said, there are no recent reports of fatalities among humans, but livestock is at risk.

While some people grow this plant as an edible or an ornamental, Chinese lantern can be invasive in some areas.

Keep that in mind, in addition to considering any grazing animals you may have around, when choosing to grow this.

Learn more about Chinese lantern in our guide.

11. Chrysanthemum

Chrysanthemums (Chrysanthemum spp.) are beloved ornamentals, and both the leaves and petals are edible.

A horizontal image of colorful chrysanthemums growing in pots outdoors.A horizontal image of colorful chrysanthemums growing in pots outdoors.

But they contain compounds that act as highly effective pest repellents and pesticides. And those same compounds can also make them unpleasant or dangerous if ingested in large amounts.

Mums contain sesquiterpene, lactones, and pyrethrins, which can be an irritant to sensitive humans and poisonous to animals.

Humans with allergies to mums can also be negatively affected. Pets might exhibit excessive drooling and vomiting if they eat this plant.

Check out our growing guide to learn more about chrysanthemums.

12. Delphinium

Stately and dramatic, delphiniums (Delphinium spp.), also known as larkspurs, are a popular garden option.

A horizontal image of a child in the garden eating a strawberry surrounded by delphinium flowersA horizontal image of a child in the garden eating a strawberry surrounded by delphinium flowers

They also contain several dangerous diterpene alkaloids. Even a small amount can kill an adult, let alone a kid or pet.

The alkaloids cause neuromuscular effects including irregular heart rhythm and paralysis.

Humans aren’t at quite as much risk as animals, though there are reports of poisoning when people have tried to use the plant medicinally.

But livestock are regularly poisoned, sometimes fatally, by wild delphiniums in forage areas.

Learn more about delphiniums in our guide.

13. Dieffenbachia

Dumb cane (Dieffenbachia spp.) got its name because it can render people unable to speak if they ingest the sap.

If you eat enough or are particularly sensitive, it could also close your airway.

A close up horizontal image of the variegated foliage of a dumb cane plant.A close up horizontal image of the variegated foliage of a dumb cane plant.

There are horrifying reports that the sap of the plant was used by slave owners in the Caribbean to punish Black slaves toiling in sugarcane fields. Other slaves used dumb cane to commit suicide.

When ingested, the sap causes swelling, making it difficult to speak and potentially paralyzing the vocal cords.

All parts of the dumb cane plant contain oxalate crystals, which cause the body to release histamines, resulting in the swelling.

While there have been reports of some deaths, and both dogs and humans have required tracheostomies to open their airways after exposure, there’s no reason not to keep the plant around if you feel confident you can keep it out of the mouths of pets and kids.

Just be careful when you work with it, and don’t ever eat it.

Learn more about dumb cane in our guide.

14. English Ivy

I discovered English ivy (Hedera helix) was toxic the hard way. I was ripping handfuls off my brick chimney, and within a few hours, my arms were covered in red welts.

Turns out, the sap inside the plant is toxic.

A horizontal image of a country house covered in English ivy with an open window.A horizontal image of a country house covered in English ivy with an open window.

All parts of the plant contain triterpenoid saponins, which cause drooling, stomach pain, diarrhea, and vomiting.

Unlike many other species, the toxin isn’t concentrated in the berries of the ivy plant, though you shouldn’t eat those either. The leaves and stems are the most toxic parts.

Most people don’t go around consuming English ivy, so it isn’t a huge threat. But if your dog likes to chew on sticks in the yard or you have sensitive skin like mine, it’s worth being wary.

You can learn more about English ivy in our guide.

15. Foxglove

Foxgloves (Digitalis purpurea) are life-saving plants when consumed correctly as medicine. If they aren’t, they can be deadly.

Consumption can result in an irregular heartbeat, slow pulse, tremors, vomiting, and seizures. It could even cause death from heart failure.

A horizontal image of pink foxgloves growing in a meadow.A horizontal image of pink foxgloves growing in a meadow.

All parts of the foxglove contain deslanoside, digitoxin, and digitalis glycoside.

Fortunately, the plant tastes super bitter, and it’s the rare golden retriever (probably) that will keep eating after one bite.

Even ingesting a little bit can make you feel awful. Imagine what it could do to a small pet if you accidentally gave them foxglove leaves rather than their usual leafy greens from the garden. Just don’t grow them near your edible garden bed.

Learn more about foxgloves in our guide.

16. Honeysuckle

Honeysuckles (Lonicera spp.) smell so sweet, so how could they be bad? All parts of the plant contain cyanogenic glycosides and carotenoids, though these are present in edible plants, too.

A horizontal image of a honeysuckle in full bloom, fading to soft focus in the background.A horizontal image of a honeysuckle in full bloom, fading to soft focus in the background.

Remember, it’s all about the dose. If you were to eat a handful of leaves, you’d probably have an upset stomach.

Although there are some species in the Lonicera genus with edible berries, don’t even think about eating them unless you know exactly what you’re dealing with.

The inedible types of berries contain more of the toxic compounds than other parts of the plant.

Even still, we’re talking about a large dose that would be required to cause much of a reaction in an adult.

The danger (and delight) with honeysuckle is that it smells heavenly. Pets and little kids might be tempted to make a meal of something besides the flowers, which are edible.

Learn more about honeysuckle in our guide.

17. Hydrangea

Hydrangeas (Hydrangea spp.) contain the cyanogenic glycoside amygdalin, which can cause intestinal discomfort at high enough doses.

A horizontal image of blue hydrangea flowers growing through and over a white picket fence.A horizontal image of blue hydrangea flowers growing through and over a white picket fence.

Fortunately for us, you’d have to eat a lot to get there. If you ate enough, you’d experience vomiting, diarrhea, and depression.

Again, the biggest risk is for those with small bodies. If they eat too much, they could be spending the next few days feeling pretty awful.

Keep the beauty of hydrangeas to the garden and out of curious mouths.

You can find more information about hydrangeas in our guide.

18. Jimson Weed

Datura, devil’s trumpet, thorn apple, or good old jimson weed (Datura stramonium). Whatever you call it, this plant is Toxic with a capital T.

It is native to and cultivated in warm regions across North America and it has also been used extensively in folk and traditional medicine.

A close up horizontal image of the flowers and foliage of jimson weed aka devil's trumpet, a poisonous plant.A close up horizontal image of the flowers and foliage of jimson weed aka devil\'s trumpet, a poisonous plant.

Some people intentionally ingest it recreationally or in religious ceremonies for the hallucinogenic effect, but it hasn’t really caught on as a recreational drug because the tropane alkaloids atropine, hyoscyamine, and scopolamine also cause unpleasant, prolonged side effects like tremors, delirium, memory loss, tachycardia, and coma.

Toxicity varies from plant to plant and region to region, with the highest concentration in the seeds. This is one poisonous plant you should definitely keep kids and pets away from.

19. Lantana

Lantana (Lantana spp.) is one of those plants whose toxic potential in humans has been overexaggerated.

Lantana isn’t going to kill you or your kids, or even make you all that sick in comparison to some poisonous plants. But it might make someone vomit or experience abdominal pain or diarrhea.

A close up horizontal image of pink and yellow lantana flowers growing in the garden pictured on a soft focus background.A close up horizontal image of pink and yellow lantana flowers growing in the garden pictured on a soft focus background.

It may seem awfully tempting to have a bite of those pretty black berries, especially if you’re a kid pretending to cook dinner.

If you were to eat enough, it could cause photosensitivity and a rapid heart rate. But nothing that is going to require hospitalization or cause death.

These effects are the result of the triterpene acids lantadene A and B that are present in all parts of the plant.

Serious issues are far more common in cattle, sheep, and horses who graze in areas where lantana grows, but it can impact guinea pigs, dogs, cats, and other small pets as well.

If ingested by these animals, it can cause liver and kidney issues.

Our guide to growing lantana provides more information about these plants.

20. Lily

Lilies (Lilium spp.), including Asiatic (L. asiaticum), Easter (L. longiflorum), Oriental (L. orientalis), and stargazer (Lilium hybrids), are extremely toxic to pets and mildly toxic to humans.

A horizontal image of a curious gray cat with a death wish eyeing up some toxic pink lilies.A horizontal image of a curious gray cat with a death wish eyeing up some toxic pink lilies.

Don’t confuse true lilies with daylilies (Hemerocallis spp.). Daylilies are edible for humans and dogs, but toxic for cats.

If ingested, early symptoms of lily poisoning in pets include drooling, depression, and vomiting.

After about 12 hours, signs of kidney failure begin, with decreased urination. Kidneys fail after about 24 hours, leading to death.

Cats are particularly sensitive, though dogs can also suffer the same symptoms.

Humans can also be sickened by eating lilies, though you’d have to eat an uncomfortable amount.

Lilies cultivated indoors are particularly tempting to cats, so be sure to keep the two apart.

Interestingly, we haven’t determined which compound causes such serious symptoms in cats, but we know it’s in the leaves and petals of the plant.

Learn more about cultivating lilies in our guide.

21. Lily of the Valley

Sweet lily of the valley (Convallaria majalis) is delicate and dainty, but its toxic effects are anything but.

This plant contains cardenolide glycosides like convallatoxin, convalloside, and lokunjoside, especially in the roots.

A close up horizontal image of white lily of the valley flowers growing in the garden.A close up horizontal image of white lily of the valley flowers growing in the garden.

If ingested, these can cause tachycardia, fibrillation, and cardiac arrest.

That doesn’t mean lily of the valley doesn’t have its uses – it can be used to make a powerful medicine to treat mild heart failure.

But a dog that takes a bite out of the sword-like leaves doesn’t know that.

This is one poisonous plant that you shouldn’t even joke about eating. If you spot symptoms in pets or humans like nausea, vomiting, chest pain, or an irregular heartbeat, seek treatment immediately.

Learn more about lily of the valley in our guide.

22. Morning Glory

The out-of-this-world color of the violet-blue, white, pink, or yellow flowers of the morning glory (Ipomoea spp.) are a red flag to keep this plant out of your mouth.

A close up horizontal image of blue morning glory flowers growing in the garden.A close up horizontal image of blue morning glory flowers growing in the garden.

Why? The seeds of I. violacea and I. indica, among other species, contain lysergic acid amide (LSA), which has similar effects as lysergic acid diethylamide (LSD).

LSA is approximately 1/10th as potent as LSD, and people sometimes consume morning glory seeds intentionally to experience hallucinogenic effects.

The seeds also cause nausea, vomiting, and abdominal pain before the psychedelic effects kick in.

Morning glory can also cause lethargy, confusion, tremors, and incoordination. Imagine how distressing this would be for a child or pet.

Learn more about morning glories in our guide.

23. Mountain Laurel

This pretty tree or shrub makes its toxicity plain. If you eat mountain laurel (Kalmia spp.), your lips, throat, and mouth will start burning.

After that, the stomach pain and vomiting kicks in. This can be accompanied by a drop in blood pressure, tremors, ataxia, and progressive paralysis, followed by coma and death.

A horizontal image of mountain laurel in full bloom pictured in light sunshine.A horizontal image of mountain laurel in full bloom pictured in light sunshine.

This isn’t one of those poisonous plants that requires a massive dose either. The diterpene compounds called grayanotoxins contained in all parts of mountain laurel are pretty potent.

This is particularly concerning for grazing animals like horses, sheep, and goats because 0.2 to 0.6 percent of an animal’s weight in leaves is all it takes to kill them.

Similar to rhododendrons and azaleas, honey made from the nectar of this mountain laurel is known as “mad honey” and it can cause blurred vision, muscle weakness, sweating, and irregular, slow heart rhythm.

You can learn more about mountain laurel in our guide.

24. Narcissus

Paperwhites and daffodils are Narcissus species that contain toxic alkaloids. Some members of the genus are more toxic than others.

A close up vertical image of a Belgian shepherd dog munching on tulip flower buds.A close up vertical image of a Belgian shepherd dog munching on tulip flower buds.

If consumed, symptoms may include dizziness and abdominal upset. And if digested in large quantities, these plants can cause convulsions.

The alkaloids that make these members of the lily family indigestible specifically affect the nervous system.

Alkaloid ingestion of this type may also result in dysfunction of the liver, and this can be fatal if consumed in large quantities. Pets are more commonly diagnosed with symptoms than humans.

While the stems, leaves, and roots all contain the toxic compound, the strongest toxin comes from deep underground, in the bulbs.

It’s typically when people dig up the bulb, thinking it’s an onion, that trouble starts. There have even been deaths attributed to accidental consumption.

People and pets have been sickened by harvesting the leaves, thinking they’re grabbing some onion greens.

Learn more about daffodils in our guide.

25. Oleander

Don’t eat oleander (Nerium oleander, N. indicum and Cascabela thevetia). Just don’t do it.

The flowers are gorgeous, but please tell your kids and pets to avoid oleander like they would a rattlesnake. Just admire it from afar.

A close up horizontal image of pink oleander flowers cascading over a wooden bench in the garden.A close up horizontal image of pink oleander flowers cascading over a wooden bench in the garden.

Although there aren’t any recent records of deaths, beyond those who ingested oleander to take their own lives, one would only need to ingest a small amount to experience its effects.

A single leaf could be deadly to a small person or animal.

All parts of oleander contain powerful cardenolides (oleandrin, nerin, digitoxigenin, and olinerin) that act on the heart.

Symptoms include stomach pain, vomiting, irregular heartbeat, cramping, bloody stools, salivation, disorientation, weakness, and death.

It may come as no surprise that this poisonous plant has been used in rat poison. Definitely not something you should eat.

Learn more about oleander in our guide.

26. Rhododendron

As with azaleas, rhododendrons (Rhododendron spp.) pose a danger if ingested.

A close up horizontal image of the pink flowers of a rhododendron growing in the garden.A close up horizontal image of the pink flowers of a rhododendron growing in the garden.

All parts of the plant are toxic thanks to the grayanotoxin they contain, and honey made from the nectar is even called “mad honey,” as noted above.

If ingested, rhododendrons can cause paralysis, convulsion, arrhythmia, hallucinations, perspiration, and low blood pressure, depending on the dose.

They sure are pretty, though, and you can learn more about them in our guide.

27. Rhubarb

Most people know that rhubarb (Rheum x hybridum, R. rhabarbarum) leaves shouldn’t be eaten, but the plant poses more of a danger than some because a curious kid might assume that because you brought in some stalks to make a pie last week, they can use some of the leaves for their tea party this week.

A horizontal image of rhubarb stalks and foliage growing in the vegetable garden pictured in light sunshine.A horizontal image of rhubarb stalks and foliage growing in the vegetable garden pictured in light sunshine.

The leaves of rhubarb are high in oxalic acid. Actually, a lot of things we eat have oxalic acid in them, but rhubarb leaves have a higher concentration.

For the most part, ingesting the leaves will lead to indigestion and stomach pain, but enough can cause kidney stones or even kidney failure.

Our guide to growing rhubarb has cultivation details.

28. Sago Palm

While every bit of the sago palm (Cycas revoluta) is somewhat toxic, from roots to tip, it’s really the nut-like seeds that cause the trouble. Pets apparently think they look delicious.

A horizontal image of large sago palms growing in the garden.A horizontal image of large sago palms growing in the garden.

The whole plant contains a glycoside called cycasin that causes dizziness, ataxia, stomach pain, vomiting, and death by liver failure, and the glycoside is concentrated in the nuts. Just two of them are enough to kill a dog.

I say “dog” because it’s usually our canine friends getting into these plants that you’ll see in news stories and articles. It seems as though cats aren’t as interested. Sadly, some of these dogs end up dying.

If you have one of those dogs that just can’t help but put everything in their mouth, you might want to consider a different kind of palm.

Interestingly, different cultures that exist far apart from one another have learned how to process the seeds to render them edible to humans.

Without this specialty knowledge, say on the safe side and skip consuming any parts of your sagos. And if you want to grow sago palms check out our guide.

29. Snake Plant

Listen, I love a snake plant. Gorgeous greenery that can pretty much be ignored and neglected?

Happy in a dark corner but still as beautiful as ever? Sounds fabulous to me! And it is an excellent plant to have around… for humans.

A close up vertical image of a cat trying to take a bite out of a snake plant.A close up vertical image of a cat trying to take a bite out of a snake plant.

Keep it away from your cats, dogs, and hamsters, though.

Dracaena trifasciata (though she’ll always be Sansevieria to me) and other species contain saponins, which can cause weakness, drooling, vomiting, diarrhea, and potentially death if they eat enough.

Learn more about growing snake plants in our guide.

30. Wisteria

Eating wisteria (Wisteria spp.) won’t harm a healthy adult much, but it can still cause some unpleasant side effects.

These could be even worse for a pet or child since they are so much smaller.

A horizontal image of wisteria seed pods hanging from an arbor.A horizontal image of wisteria seed pods hanging from an arbor.

Wisteria contains glycosides known as lectin and wisterin, which cause mouth and stomach pain, vomiting, depression, and diarrhea.

I hear you wondering why anyone would want to eat wisteria.

The vines produce seed pods after they flower, and you can forgive curious minds for considering trying a few just to see what they taste like.

Our guide to growing wisteria has cultivation instructions.

31. Yew

Yews (Taxus spp.) are long-lived evergreens that have found their way into gardens across the globe. It’s also one of the most notoriously toxic plants in the US and Europe.

A close up horizontal image of the red berries and green foliage of European yew, a highly toxic plant.A close up horizontal image of the red berries and green foliage of European yew, a highly toxic plant.

All parts of the plant contain the toxic alkaloid taxane, which acts on the cardiac system and can result in death if enough is ingested.

Having said that, death is extremely rare and usually only occurs in people who want to take their own lives.

But it doesn’t take much to cause symptoms like heart arrhythmia, vomiting, nausea, and convulsions.

The flesh of the aril around the seed is actually edible, but the leaves aren’t, and neither is the seed inside the flesh. A few seeds could prove toxic.

Annoyingly, the bright red berries could prove appealing, especially to kids, and there are recent reports of life-threatening exposures.

Learn more about yew trees and shrubs in our guide.

The Poison Is in the Dose

I don’t want to scare you away from growing any of the poisonous plants on this list.

Just use your best judgment, teach your kids not to eat things without talking to you first, and prevent dogs and cats that can’t resist putting things in their mouths from accessing toxic plants.

That way, you can still enjoy your favorite species.

A close up horizontal image of a yellow Labrador retriever dog sitting in the garden surrounded by pink rhododendron flowers.A close up horizontal image of a yellow Labrador retriever dog sitting in the garden surrounded by pink rhododendron flowers.

Have you ever had any experience with any of these plants? Fill us in on all the details your experiences in the comments.

Maybe you’re tired of hearing about all this potential danger. I hear you. If you’re interested in learning about a few edible options, we have some guides that you might find useful:

  • How to Harvest Edible Flowers
  • 69 Incredible Edible Flowers and How to Use Them
  • 39 Common Weeds That You Can Eat or Use For Medicine

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